A case of death wobble today
#241
Guest
Posts: n/a
Re: A case of death wobble today
Come again?
L.W.(ßill) ------ III wrote:
> Except putting a longer shackle on increases it's leverage on the
> spring, almost instantly pulling the arc out of the spring, for no
> change.
> God Bless America, ßill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Old Crow wrote:
>
>>They would be if some of the height is gained by using the lift
>>shackles. I was looking at these as a cheap way to lift my YJ, but it
>>didn't take an engineer to tell me that lifing one end of the springs
>>is going to rotate the axle and thus change the castor angles.
>>
>>--
>>Old Crow
>>'82 Shovelhead FLT 92" 'Pearl'
>>'95 Jeep YJ Rio Grande
>>ASE Certified Master Auto Tech + L1
>>TOMKAT, BS#133, SENS, MAMBM, DOF#51
L.W.(ßill) ------ III wrote:
> Except putting a longer shackle on increases it's leverage on the
> spring, almost instantly pulling the arc out of the spring, for no
> change.
> God Bless America, ßill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Old Crow wrote:
>
>>They would be if some of the height is gained by using the lift
>>shackles. I was looking at these as a cheap way to lift my YJ, but it
>>didn't take an engineer to tell me that lifing one end of the springs
>>is going to rotate the axle and thus change the castor angles.
>>
>>--
>>Old Crow
>>'82 Shovelhead FLT 92" 'Pearl'
>>'95 Jeep YJ Rio Grande
>>ASE Certified Master Auto Tech + L1
>>TOMKAT, BS#133, SENS, MAMBM, DOF#51
#242
Guest
Posts: n/a
Re: A case of death wobble today
3/16" toe in is excessive for large tires, one wheel with total
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might be
> shot. He suggested replacing it (he's also the 2nd mechanic that suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link tothe
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might be
> shot. He suggested replacing it (he's also the 2nd mechanic that suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link tothe
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>
#243
Guest
Posts: n/a
Re: A case of death wobble today
3/16" toe in is excessive for large tires, one wheel with total
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might be
> shot. He suggested replacing it (he's also the 2nd mechanic that suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link tothe
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might be
> shot. He suggested replacing it (he's also the 2nd mechanic that suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link tothe
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>
#244
Guest
Posts: n/a
Re: A case of death wobble today
3/16" toe in is excessive for large tires, one wheel with total
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might be
> shot. He suggested replacing it (he's also the 2nd mechanic that suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link tothe
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might be
> shot. He suggested replacing it (he's also the 2nd mechanic that suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link tothe
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>
#245
Guest
Posts: n/a
Re: A case of death wobble today
Since I was forced to change my e-mail address (SVEN virus
fallout) and keeping the real address hidden, I have had (TA DA
!!!) ZERO SPAM in 4 months! I could get to like this. Just like
the old days when "You've got mail" was not another deluge of
Korean ----.
CRWLR wrote:
> It worked, except that my address has already been sold at least once, and
> probably thousands of times. I get more spam from Korea ...
>
>
>
>
> "L.W. (ßill) ------ III" <----------@***.net> wrote in message
> news:403A612D.9544C785@***.net...
>
>> Good luck.
>> God Bless America, ßill O|||||||O
>>mailto:-------------------- http://www.----------.com/
>>
>>CRWLR wrote:
>>
>>>I always was told that there are spambots that search Usenet to harvest
>>>email address that reside in the headers. I am convinced that my address
>
> was
>
>>>harvested, probably only once, and then was sold on the open market. In
>
> any
>
>>>case, I was forced to put a fake address in my newsgroup headers in the
>>>effort to hope that the spambots would be rendered harmless to me.
>
>
fallout) and keeping the real address hidden, I have had (TA DA
!!!) ZERO SPAM in 4 months! I could get to like this. Just like
the old days when "You've got mail" was not another deluge of
Korean ----.
CRWLR wrote:
> It worked, except that my address has already been sold at least once, and
> probably thousands of times. I get more spam from Korea ...
>
>
>
>
> "L.W. (ßill) ------ III" <----------@***.net> wrote in message
> news:403A612D.9544C785@***.net...
>
>> Good luck.
>> God Bless America, ßill O|||||||O
>>mailto:-------------------- http://www.----------.com/
>>
>>CRWLR wrote:
>>
>>>I always was told that there are spambots that search Usenet to harvest
>>>email address that reside in the headers. I am convinced that my address
>
> was
>
>>>harvested, probably only once, and then was sold on the open market. In
>
> any
>
>>>case, I was forced to put a fake address in my newsgroup headers in the
>>>effort to hope that the spambots would be rendered harmless to me.
>
>
#246
Guest
Posts: n/a
Re: A case of death wobble today
Since I was forced to change my e-mail address (SVEN virus
fallout) and keeping the real address hidden, I have had (TA DA
!!!) ZERO SPAM in 4 months! I could get to like this. Just like
the old days when "You've got mail" was not another deluge of
Korean ----.
CRWLR wrote:
> It worked, except that my address has already been sold at least once, and
> probably thousands of times. I get more spam from Korea ...
>
>
>
>
> "L.W. (ßill) ------ III" <----------@***.net> wrote in message
> news:403A612D.9544C785@***.net...
>
>> Good luck.
>> God Bless America, ßill O|||||||O
>>mailto:-------------------- http://www.----------.com/
>>
>>CRWLR wrote:
>>
>>>I always was told that there are spambots that search Usenet to harvest
>>>email address that reside in the headers. I am convinced that my address
>
> was
>
>>>harvested, probably only once, and then was sold on the open market. In
>
> any
>
>>>case, I was forced to put a fake address in my newsgroup headers in the
>>>effort to hope that the spambots would be rendered harmless to me.
>
>
fallout) and keeping the real address hidden, I have had (TA DA
!!!) ZERO SPAM in 4 months! I could get to like this. Just like
the old days when "You've got mail" was not another deluge of
Korean ----.
CRWLR wrote:
> It worked, except that my address has already been sold at least once, and
> probably thousands of times. I get more spam from Korea ...
>
>
>
>
> "L.W. (ßill) ------ III" <----------@***.net> wrote in message
> news:403A612D.9544C785@***.net...
>
>> Good luck.
>> God Bless America, ßill O|||||||O
>>mailto:-------------------- http://www.----------.com/
>>
>>CRWLR wrote:
>>
>>>I always was told that there are spambots that search Usenet to harvest
>>>email address that reside in the headers. I am convinced that my address
>
> was
>
>>>harvested, probably only once, and then was sold on the open market. In
>
> any
>
>>>case, I was forced to put a fake address in my newsgroup headers in the
>>>effort to hope that the spambots would be rendered harmless to me.
>
>
#247
Guest
Posts: n/a
Re: A case of death wobble today
Since I was forced to change my e-mail address (SVEN virus
fallout) and keeping the real address hidden, I have had (TA DA
!!!) ZERO SPAM in 4 months! I could get to like this. Just like
the old days when "You've got mail" was not another deluge of
Korean ----.
CRWLR wrote:
> It worked, except that my address has already been sold at least once, and
> probably thousands of times. I get more spam from Korea ...
>
>
>
>
> "L.W. (ßill) ------ III" <----------@***.net> wrote in message
> news:403A612D.9544C785@***.net...
>
>> Good luck.
>> God Bless America, ßill O|||||||O
>>mailto:-------------------- http://www.----------.com/
>>
>>CRWLR wrote:
>>
>>>I always was told that there are spambots that search Usenet to harvest
>>>email address that reside in the headers. I am convinced that my address
>
> was
>
>>>harvested, probably only once, and then was sold on the open market. In
>
> any
>
>>>case, I was forced to put a fake address in my newsgroup headers in the
>>>effort to hope that the spambots would be rendered harmless to me.
>
>
fallout) and keeping the real address hidden, I have had (TA DA
!!!) ZERO SPAM in 4 months! I could get to like this. Just like
the old days when "You've got mail" was not another deluge of
Korean ----.
CRWLR wrote:
> It worked, except that my address has already been sold at least once, and
> probably thousands of times. I get more spam from Korea ...
>
>
>
>
> "L.W. (ßill) ------ III" <----------@***.net> wrote in message
> news:403A612D.9544C785@***.net...
>
>> Good luck.
>> God Bless America, ßill O|||||||O
>>mailto:-------------------- http://www.----------.com/
>>
>>CRWLR wrote:
>>
>>>I always was told that there are spambots that search Usenet to harvest
>>>email address that reside in the headers. I am convinced that my address
>
> was
>
>>>harvested, probably only once, and then was sold on the open market. In
>
> any
>
>>>case, I was forced to put a fake address in my newsgroup headers in the
>>>effort to hope that the spambots would be rendered harmless to me.
>
>
#248
Guest
Posts: n/a
Re: A case of death wobble today
Yep, I have one on order. It's hard to find a good stabilizer in this town.
Got a pre-72 CJ style stabilizer with bracketry on the way since the stock
bracketry went away with the D30 I replaced.
Terry.
"Roy J" <spamless@microsoft.net> wrote in message
news:Z%J_b.5$X%2.18370@news.uswest.net...
3/16" toe in is excessive for large tires, one wheel with total
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might
be
> shot. He suggested replacing it (he's also the 2nd mechanic that
suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be
a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link to
the
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>
Got a pre-72 CJ style stabilizer with bracketry on the way since the stock
bracketry went away with the D30 I replaced.
Terry.
"Roy J" <spamless@microsoft.net> wrote in message
news:Z%J_b.5$X%2.18370@news.uswest.net...
3/16" toe in is excessive for large tires, one wheel with total
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might
be
> shot. He suggested replacing it (he's also the 2nd mechanic that
suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be
a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link to
the
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>
#249
Guest
Posts: n/a
Re: A case of death wobble today
Yep, I have one on order. It's hard to find a good stabilizer in this town.
Got a pre-72 CJ style stabilizer with bracketry on the way since the stock
bracketry went away with the D30 I replaced.
Terry.
"Roy J" <spamless@microsoft.net> wrote in message
news:Z%J_b.5$X%2.18370@news.uswest.net...
3/16" toe in is excessive for large tires, one wheel with total
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might
be
> shot. He suggested replacing it (he's also the 2nd mechanic that
suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be
a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link to
the
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>
Got a pre-72 CJ style stabilizer with bracketry on the way since the stock
bracketry went away with the D30 I replaced.
Terry.
"Roy J" <spamless@microsoft.net> wrote in message
news:Z%J_b.5$X%2.18370@news.uswest.net...
3/16" toe in is excessive for large tires, one wheel with total
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might
be
> shot. He suggested replacing it (he's also the 2nd mechanic that
suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be
a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link to
the
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>
#250
Guest
Posts: n/a
Re: A case of death wobble today
Yep, I have one on order. It's hard to find a good stabilizer in this town.
Got a pre-72 CJ style stabilizer with bracketry on the way since the stock
bracketry went away with the D30 I replaced.
Terry.
"Roy J" <spamless@microsoft.net> wrote in message
news:Z%J_b.5$X%2.18370@news.uswest.net...
3/16" toe in is excessive for large tires, one wheel with total
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might
be
> shot. He suggested replacing it (he's also the 2nd mechanic that
suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be
a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link to
the
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>
Got a pre-72 CJ style stabilizer with bracketry on the way since the stock
bracketry went away with the D30 I replaced.
Terry.
"Roy J" <spamless@microsoft.net> wrote in message
news:Z%J_b.5$X%2.18370@news.uswest.net...
3/16" toe in is excessive for large tires, one wheel with total
of 12 oz is a LOT. That will kick off DW, fix those.
**NOW** you can go change the stabilzier!!
Cheers.
Terry Jeffrey wrote:
> No need for the arguing.
>
> Here's the scoop so far:
>
> 1) Caster set at 6 degrees positive, which is Ok,
> 2) My right front lost two wheel weights (6ozs), not Ok,
> 3) My toe-in (which I set myself) was at 3/16"; he adjusted to 1/16",
> 4) Front tires are worn which I plan to rotate to the back,
> 5) Mechanic fella thought the steering stabilizer was too soft and might
be
> shot. He suggested replacing it (he's also the 2nd mechanic that
suggested
> ditching the track bar).
>
> I haven't tested it out yet on that same stretch of bumpy road, but might
> tonight. Or I might wait until I get the new stabilizer on.
>
> If it is gone, the DW was probably caused by a combination of these items.
>
> Thanks again for all the helpful comments and suggestions.
>
> Terry
> 92YJ
>
>
>
>
> "Roy J" <spamless@microsoft.net> wrote in message
> news:1Yf_b.131$pT1.86178@news.uswest.net...
> Since this seems to be the argument of the week, I went off and
> did some calculations. Sigh. I hate being an engineer.
>
> A while back there was a guy from the east coast, helicopter
> pilot, etc that had a built TJ (sorry I can't pull up his name)
> and we got into the discussion of DW on the TJ. He finally
> convinced me that big tires need LESS caster than stock tires
> (say about 5 degrees) rather than the 6 to 7 degrees on the
> various shop specs. And that the toe in on big tires needs to be
> as close to zero as you can get and still be toe in.
>
> The OP stated that he has the 1" lift Confer shackles (that are
> 2" longer than stock) Sin (2"/45") is 2.56 degrees. So the OP is
> shorting himself 2.5 degrees on the caster (unless he has added
> the appropriate shims of course) Every inch lowering in the front
> shaves another .6 degree off the caster. So if he hits the brakes
> and gets 3" of front dive, he shaves another 2 degrees off the
> caster. If he has any permamanet spring wrap, he will shave off
> some more. (35" tires and a D60 probably means he pushes it a
> little!)
>
> The OP stated that he has high mileage on his 35" tires. Most of
> us have not solved the problem of perfect wear on big tires so
> I'll assume that they are not worn evenly. He did not state if he
> had balanced them lately but even then, did he shuck a wheel weight?
>
> The OP has the reversed tie rod , this changes things from what
> most of us run.
>
> Th OP told Dynatrac about his vehicle, did he indicate he was
> going to use the Confer shackles? And does Dynatrac set up the
> axle for a specified caster angle??? Ie do they do factory stock
> or what works??
>
> When we tackle a harmonic vibration problem (and this is a
> special case of the general theory) we have 4 basic methods to
> deal with things:
> 1) change the freqeuency of the system
> 2) "Stiffen" the system to move the harmonic up higher.
> 3) Dampen the system
> 4) Reduce the input energy at the vibration frequency to keep if
> from going off.
>
> In a Jeep, #1 is tough, it has to move through a range of
> frequencies (speeds)
>
> #2 involves tightening up the slop in the system (tie rod ends,
> ball joints, heavier tie rod, etc) Plus you need enough toe in to
> keep the system preloaded one direction.
>
> #3 is the infamous steering stabilzer.
>
> #4 is mostly from the tires. They need to be dynamicly balanced
> at the frequency in question (about 60 mph) AND they need to be
> round and straight. Keep in mind that 35" tires run almost 100
> pounds a piece, I have seen them worn down with up to 1/4" cups
> and waves in them. Lots of side energy available here.
>
> Net: I'll sit here and speculate that the actual caster is way
> less than the OP thinks it is, that the tires are worn and out of
> balance (not a lot but enough!), that he hit the brakes and a
> bump with a bit of a turn, the whole works started to shake, and
> the steering stabilzer was not up to the job of getting control
> back. Take your choice of fixes, I personally prefer naturally
> stable systems to ones that are subject to failure from the
> fatigue of a single component.
>
> Cheers.
>
>
> CRWLR wrote:
>
>
>>Think of how the forks on a motorcycle are raked. A chopper goes straighat
>>ahead really good, but can be a bitch to turn, and a racing bike can turn
>
> on
>
>>a dime, but the steering is very twitchy. The most significant difference
>
> in
>
>>these examples is the rake of the forks, and this rake is similar to the
>>Caster angle.
>>
>>As I said earlier, caster typically does not play a large role in the
>>adjustments of the front end geometry because it is pretty much set during
>>manufacturing of the axle. The spring perches define the caster angle.
>>Assuming the axle is the right one, the caster angle should be right. Of
>>course, with custom modifications - lift - the caster angle can change
>>enough to become a player in DW.
>>
>>Caster angle is the imaginary line through the upper and lower ball
>
> joints,
>
>>and the center of the spindle. Properly set, the caster angle should be
>>about 7° towards the rear of the vehicle. That is, the upper ball joint
>>should trail the lower by about 7°. Perhaps the number is a little bit
>>different in your case, but greater angles will be more stable than lesser
>>angles. When the angle drops to about 4° or less, then the tires will
>
> search
>
>>for the straight ahead position, and this sets up the DW symptoms. There
>
> is
>
>>an easy test for Caster angle ... Go to an open area and make a Uturn, or
>
> a
>
>>manuver that simulates what you might do when backing from a parking
>
> stall.
>
>>Turn the steering wheel fully to one stop, then begin going and see if the
>>wheel returns to center on its own, or if it remains in Turning Mode and
>>requires you to physically turn back to center. If you have to drive it
>
> back
>
>>to straight ahead, then your caster is not great enough, but if it wants
>
> to
>
>>go to center on its own, then the caster is probably OK.
>>
>>In my motorcycle analogy, there are other geometry forces at play, so the
>>analogy breaks down pretty quickly, but in general terms, it works pretty
>>well. I am certain that my analogy will be corrected, but it works for
>
> now.
>
>>My FSM says the spec for Caster angle is 6°.
>>
>>
>>
>>
>>
>>"Terry Jeffrey" <twjeffrey@hotmail.com> wrote in message
>>news:a5SZb.4126$aT1.454@newsread1.news.pas.earth link.net...
>>
>>
>>>The ball joints appear to be good. I did the push-pull-raised-tire test
>>
>>and
>>
>>
>>>it checked out Ok. All the rod ends are tight and lubed. I'll get the
>>>caster checked out next week. Explain, if you will, why caster would be
a
>>>player in DW. This could be my problem. If the caster angle is off,
>>>wouldn't this only cause the vehicle to pull to one side or the other?
>>>
>>>It was suggested to move the steering stabilizer from the drag link to
the
>>>tie rod. When I did this, I still got the same DW. I thought I felt a
>>>little air in the stabilizer at the extended end while testing it, and
>>
>>will
>>
>>
>>>replace it as soon as I can find one.
>>>
>>>Your track bar comment is noted. I'd like to leave it off all together
>>>because real estate up front is a premium right now with the Dana60. But
>>>will put it back on nice and tight and put the DW to the test again.
>>>
>>>Thanks again,
>>>Terry.
>>>
>>>
>>>
>>>
>>>"CRWLR" <CRWLRJEFF@YAHOO.COM> wrote in message
>>>news:103foc9kj445236@corp.supernews.com...
>>>
>>>
>>>>If all of that stuff is new, I would not think the steering stabalizer
>>>
>>>would
>>>
>>>
>>>>be so significant. Did you attempt the tests that I described? (If I
>>>>described something incorrectly, did you try what might have been
>>>
>>>suggested
>>>
>>>
>>>>to correct me?)
>>>>
>>>>If you suspect the track bar is worn, and causing a problem with
>>>
>>>looseness,
>>>
>>>
>>>>then removing the trackbar altogether is not much of a confirmation
>>
>>test.
>>
>>
>>>If
>>>
>>>
>>>>yo had no trackbar, and complained of DW, then put the bar on to see if
>>>
>>>the
>>>
>>>
>>>>DW went away, then you would have a reasonable diagnostic test. Taking
>>
>>the
>>
>>
>>>>trackbar off is the same thing as having one on that had worn bushings.
>>>>
>
>
>