Lift & Driveline problems
12-31-2003, 08:18 AM
#51
Guest
Posts: n/a
Re: Lift & Driveline problems
The stock TJ *does* have a 2nd u-joint. It's just closer to the 1st u-joint
than it needs to be, since the slip joint is outboard of the driveshaft
instead of in the middle. This results in a shorter driveshaft and higher
angles and therein lies the problem.
The advantage of the CV joints is twofold. First, they allow (require) the
u-joint on the other end to be aligned differently (because of the second
advantage), raising the pinion and reducing the angles of the driveshaft.
Second (and the reason for the first, above), they don't accelerate and
decelerate the driveshaft with each revolution (since they are made of two
out of phase u-joints), which is part of the cause of the vibrations in the
first place. That's why they are called "constant velocity" joints.
--
Jim
--
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98
"You can do any job in the world with the wrong tool if you try hard
enough..."
"4x4" in caps is "$X$"
"Tim Hayes" <thayes@remove-me.rutgers.edu> wrote in message
news:3ff20db9@rutgers.edu...
> Isn't the angle only an issue in two ways?
>
> 1) a u-joint has a maximum angle it can operate through
>
> 2) the angle on both ends of a 2 u-joint driveshaft must be the same
>
> Since a stock TJ doesn't have a second u-joint won't you always violate
> #2 except at one specific ride height (and even then whenever you flex
> over a bump)?
>
> Couldn't you correct #2 by adding the second u-joint without lengthening
> the driveshaft provided you don't violate #1?
>
> This is all from my mechanical engineering classed in college so maybe
> I've got it wrong. It isn't like i've ever actually built a drivetrain
> myself, but I thought I understood the theory pretty well.
>
> Jerry Bransford wrote:
>
> > Tim, it's not the slip yoke itself that causes vibrations, it's only the
> > driveshaft angle that does. That the Rubicon has moved the slip yoke to
the
> > driveshaft doesn't change the lift height that will cause drivetrain
> > vibrations. That the Rubicon has a slightly longer driveshaft due to the
> > elimination of the t-case slip yoke will help though. :)
>
than it needs to be, since the slip joint is outboard of the driveshaft
instead of in the middle. This results in a shorter driveshaft and higher
angles and therein lies the problem.
The advantage of the CV joints is twofold. First, they allow (require) the
u-joint on the other end to be aligned differently (because of the second
advantage), raising the pinion and reducing the angles of the driveshaft.
Second (and the reason for the first, above), they don't accelerate and
decelerate the driveshaft with each revolution (since they are made of two
out of phase u-joints), which is part of the cause of the vibrations in the
first place. That's why they are called "constant velocity" joints.
--
Jim
--
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98
"You can do any job in the world with the wrong tool if you try hard
enough..."
"4x4" in caps is "$X$"
"Tim Hayes" <thayes@remove-me.rutgers.edu> wrote in message
news:3ff20db9@rutgers.edu...
> Isn't the angle only an issue in two ways?
>
> 1) a u-joint has a maximum angle it can operate through
>
> 2) the angle on both ends of a 2 u-joint driveshaft must be the same
>
> Since a stock TJ doesn't have a second u-joint won't you always violate
> #2 except at one specific ride height (and even then whenever you flex
> over a bump)?
>
> Couldn't you correct #2 by adding the second u-joint without lengthening
> the driveshaft provided you don't violate #1?
>
> This is all from my mechanical engineering classed in college so maybe
> I've got it wrong. It isn't like i've ever actually built a drivetrain
> myself, but I thought I understood the theory pretty well.
>
> Jerry Bransford wrote:
>
> > Tim, it's not the slip yoke itself that causes vibrations, it's only the
> > driveshaft angle that does. That the Rubicon has moved the slip yoke to
the
> > driveshaft doesn't change the lift height that will cause drivetrain
> > vibrations. That the Rubicon has a slightly longer driveshaft due to the
> > elimination of the t-case slip yoke will help though. :)
>
12-31-2003, 08:18 AM
#52
Guest
Posts: n/a
Re: Lift & Driveline problems
The stock TJ *does* have a 2nd u-joint. It's just closer to the 1st u-joint
than it needs to be, since the slip joint is outboard of the driveshaft
instead of in the middle. This results in a shorter driveshaft and higher
angles and therein lies the problem.
The advantage of the CV joints is twofold. First, they allow (require) the
u-joint on the other end to be aligned differently (because of the second
advantage), raising the pinion and reducing the angles of the driveshaft.
Second (and the reason for the first, above), they don't accelerate and
decelerate the driveshaft with each revolution (since they are made of two
out of phase u-joints), which is part of the cause of the vibrations in the
first place. That's why they are called "constant velocity" joints.
--
Jim
--
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98
"You can do any job in the world with the wrong tool if you try hard
enough..."
"4x4" in caps is "$X$"
"Tim Hayes" <thayes@remove-me.rutgers.edu> wrote in message
news:3ff20db9@rutgers.edu...
> Isn't the angle only an issue in two ways?
>
> 1) a u-joint has a maximum angle it can operate through
>
> 2) the angle on both ends of a 2 u-joint driveshaft must be the same
>
> Since a stock TJ doesn't have a second u-joint won't you always violate
> #2 except at one specific ride height (and even then whenever you flex
> over a bump)?
>
> Couldn't you correct #2 by adding the second u-joint without lengthening
> the driveshaft provided you don't violate #1?
>
> This is all from my mechanical engineering classed in college so maybe
> I've got it wrong. It isn't like i've ever actually built a drivetrain
> myself, but I thought I understood the theory pretty well.
>
> Jerry Bransford wrote:
>
> > Tim, it's not the slip yoke itself that causes vibrations, it's only the
> > driveshaft angle that does. That the Rubicon has moved the slip yoke to
the
> > driveshaft doesn't change the lift height that will cause drivetrain
> > vibrations. That the Rubicon has a slightly longer driveshaft due to the
> > elimination of the t-case slip yoke will help though. :)
>
than it needs to be, since the slip joint is outboard of the driveshaft
instead of in the middle. This results in a shorter driveshaft and higher
angles and therein lies the problem.
The advantage of the CV joints is twofold. First, they allow (require) the
u-joint on the other end to be aligned differently (because of the second
advantage), raising the pinion and reducing the angles of the driveshaft.
Second (and the reason for the first, above), they don't accelerate and
decelerate the driveshaft with each revolution (since they are made of two
out of phase u-joints), which is part of the cause of the vibrations in the
first place. That's why they are called "constant velocity" joints.
--
Jim
--
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98
"You can do any job in the world with the wrong tool if you try hard
enough..."
"4x4" in caps is "$X$"
"Tim Hayes" <thayes@remove-me.rutgers.edu> wrote in message
news:3ff20db9@rutgers.edu...
> Isn't the angle only an issue in two ways?
>
> 1) a u-joint has a maximum angle it can operate through
>
> 2) the angle on both ends of a 2 u-joint driveshaft must be the same
>
> Since a stock TJ doesn't have a second u-joint won't you always violate
> #2 except at one specific ride height (and even then whenever you flex
> over a bump)?
>
> Couldn't you correct #2 by adding the second u-joint without lengthening
> the driveshaft provided you don't violate #1?
>
> This is all from my mechanical engineering classed in college so maybe
> I've got it wrong. It isn't like i've ever actually built a drivetrain
> myself, but I thought I understood the theory pretty well.
>
> Jerry Bransford wrote:
>
> > Tim, it's not the slip yoke itself that causes vibrations, it's only the
> > driveshaft angle that does. That the Rubicon has moved the slip yoke to
the
> > driveshaft doesn't change the lift height that will cause drivetrain
> > vibrations. That the Rubicon has a slightly longer driveshaft due to the
> > elimination of the t-case slip yoke will help though. :)
>
12-31-2003, 08:26 AM
#53
Guest
Posts: n/a
Re: Lift & Driveline problems
Absolutely correct. :-) The solution to the vibration, therefore, is
either to reduce the angle of the u-joints (driveshaft) or add a CV joint
which will only accelerate and decelerate the coupling between the two
u-joints it's built out of rather than the much greater mass of the
driveshaft. (The lower (3rd) u-joint is then aligned with no angle and,
therefore doesn't cause any cycling of forces.)
--
Jim
--
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98
"You can do any job in the world with the wrong tool if you try hard
enough..."
"4x4" in caps is "$X$"
"Tim Hayes" <thayes@remove-me.rutgers.edu> wrote in message
news:3ff26896$1@rutgers.edu...
> Great link! Thanks!
>
> So:
>
> - A larger u-joint angle means a more elliptical path for the driveshaft
> ends of the two joints.
>
> - This causes a greater velocity variance as the joint turns through
> every 180 degrees.
>
> - The changes to velocity require acceleration/deceleration of the shaft.
>
> - Acceleration/deceleration requires the application of force to the
shaft.
>
> - The changing forces are felt as vibration in the system.
>
either to reduce the angle of the u-joints (driveshaft) or add a CV joint
which will only accelerate and decelerate the coupling between the two
u-joints it's built out of rather than the much greater mass of the
driveshaft. (The lower (3rd) u-joint is then aligned with no angle and,
therefore doesn't cause any cycling of forces.)
--
Jim
--
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98
"You can do any job in the world with the wrong tool if you try hard
enough..."
"4x4" in caps is "$X$"
"Tim Hayes" <thayes@remove-me.rutgers.edu> wrote in message
news:3ff26896$1@rutgers.edu...
> Great link! Thanks!
>
> So:
>
> - A larger u-joint angle means a more elliptical path for the driveshaft
> ends of the two joints.
>
> - This causes a greater velocity variance as the joint turns through
> every 180 degrees.
>
> - The changes to velocity require acceleration/deceleration of the shaft.
>
> - Acceleration/deceleration requires the application of force to the
shaft.
>
> - The changing forces are felt as vibration in the system.
>
12-31-2003, 08:26 AM
#54
Guest
Posts: n/a
Re: Lift & Driveline problems
Absolutely correct. :-) The solution to the vibration, therefore, is
either to reduce the angle of the u-joints (driveshaft) or add a CV joint
which will only accelerate and decelerate the coupling between the two
u-joints it's built out of rather than the much greater mass of the
driveshaft. (The lower (3rd) u-joint is then aligned with no angle and,
therefore doesn't cause any cycling of forces.)
--
Jim
--
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98
"You can do any job in the world with the wrong tool if you try hard
enough..."
"4x4" in caps is "$X$"
"Tim Hayes" <thayes@remove-me.rutgers.edu> wrote in message
news:3ff26896$1@rutgers.edu...
> Great link! Thanks!
>
> So:
>
> - A larger u-joint angle means a more elliptical path for the driveshaft
> ends of the two joints.
>
> - This causes a greater velocity variance as the joint turns through
> every 180 degrees.
>
> - The changes to velocity require acceleration/deceleration of the shaft.
>
> - Acceleration/deceleration requires the application of force to the
shaft.
>
> - The changing forces are felt as vibration in the system.
>
either to reduce the angle of the u-joints (driveshaft) or add a CV joint
which will only accelerate and decelerate the coupling between the two
u-joints it's built out of rather than the much greater mass of the
driveshaft. (The lower (3rd) u-joint is then aligned with no angle and,
therefore doesn't cause any cycling of forces.)
--
Jim
--
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98
"You can do any job in the world with the wrong tool if you try hard
enough..."
"4x4" in caps is "$X$"
"Tim Hayes" <thayes@remove-me.rutgers.edu> wrote in message
news:3ff26896$1@rutgers.edu...
> Great link! Thanks!
>
> So:
>
> - A larger u-joint angle means a more elliptical path for the driveshaft
> ends of the two joints.
>
> - This causes a greater velocity variance as the joint turns through
> every 180 degrees.
>
> - The changes to velocity require acceleration/deceleration of the shaft.
>
> - Acceleration/deceleration requires the application of force to the
shaft.
>
> - The changing forces are felt as vibration in the system.
>
12-31-2003, 08:26 AM
#55
Guest
Posts: n/a
Re: Lift & Driveline problems
Absolutely correct. :-) The solution to the vibration, therefore, is
either to reduce the angle of the u-joints (driveshaft) or add a CV joint
which will only accelerate and decelerate the coupling between the two
u-joints it's built out of rather than the much greater mass of the
driveshaft. (The lower (3rd) u-joint is then aligned with no angle and,
therefore doesn't cause any cycling of forces.)
--
Jim
--
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98
"You can do any job in the world with the wrong tool if you try hard
enough..."
"4x4" in caps is "$X$"
"Tim Hayes" <thayes@remove-me.rutgers.edu> wrote in message
news:3ff26896$1@rutgers.edu...
> Great link! Thanks!
>
> So:
>
> - A larger u-joint angle means a more elliptical path for the driveshaft
> ends of the two joints.
>
> - This causes a greater velocity variance as the joint turns through
> every 180 degrees.
>
> - The changes to velocity require acceleration/deceleration of the shaft.
>
> - Acceleration/deceleration requires the application of force to the
shaft.
>
> - The changing forces are felt as vibration in the system.
>
either to reduce the angle of the u-joints (driveshaft) or add a CV joint
which will only accelerate and decelerate the coupling between the two
u-joints it's built out of rather than the much greater mass of the
driveshaft. (The lower (3rd) u-joint is then aligned with no angle and,
therefore doesn't cause any cycling of forces.)
--
Jim
--
98 TJ SE
90 SJ GW
http://www.delawareja.com/gallery/JDJeep98
"You can do any job in the world with the wrong tool if you try hard
enough..."
"4x4" in caps is "$X$"
"Tim Hayes" <thayes@remove-me.rutgers.edu> wrote in message
news:3ff26896$1@rutgers.edu...
> Great link! Thanks!
>
> So:
>
> - A larger u-joint angle means a more elliptical path for the driveshaft
> ends of the two joints.
>
> - This causes a greater velocity variance as the joint turns through
> every 180 degrees.
>
> - The changes to velocity require acceleration/deceleration of the shaft.
>
> - Acceleration/deceleration requires the application of force to the
shaft.
>
> - The changing forces are felt as vibration in the system.
>
12-31-2003, 09:05 AM
#56
Guest
Posts: n/a
Re: Lift & Driveline problems
In article <3FF246C3.7B6E3D82@***.net>, L.W.(=?iso-8859-1?Q?=DFill?=) ------
III <----------@***.net> writes:
> Would you believe the '02 Factory Repair Manual has it pictured:
>http://www.----------.com/03TJCV.pdf
As does my '00 FSM, but as we're talking about rear driveshafts, Bill, you are
again grasping the irrelevent. Would you believe that every TJ has a CV joint
in the stock front driveshaft, and NO TJ from the factory has ever had a CV
joint in the rear.
Picture of a stock rear Rubicon shaft:
http://www.geocities.com/basscraft.geo/slipjoint.jpg
* * *
Matt Macchiarolo
www.townpeddler.com
www.wolverine4wd.org
http://wolverine4wd.org/rigs/macchiarolo_ml.html
III <----------@***.net> writes:
> Would you believe the '02 Factory Repair Manual has it pictured:
>http://www.----------.com/03TJCV.pdf
As does my '00 FSM, but as we're talking about rear driveshafts, Bill, you are
again grasping the irrelevent. Would you believe that every TJ has a CV joint
in the stock front driveshaft, and NO TJ from the factory has ever had a CV
joint in the rear.
Picture of a stock rear Rubicon shaft:
http://www.geocities.com/basscraft.geo/slipjoint.jpg
* * *
Matt Macchiarolo
www.townpeddler.com
www.wolverine4wd.org
http://wolverine4wd.org/rigs/macchiarolo_ml.html
12-31-2003, 09:05 AM
#57
Guest
Posts: n/a
Re: Lift & Driveline problems
In article <3FF246C3.7B6E3D82@***.net>, L.W.(=?iso-8859-1?Q?=DFill?=) ------
III <----------@***.net> writes:
> Would you believe the '02 Factory Repair Manual has it pictured:
>http://www.----------.com/03TJCV.pdf
As does my '00 FSM, but as we're talking about rear driveshafts, Bill, you are
again grasping the irrelevent. Would you believe that every TJ has a CV joint
in the stock front driveshaft, and NO TJ from the factory has ever had a CV
joint in the rear.
Picture of a stock rear Rubicon shaft:
http://www.geocities.com/basscraft.geo/slipjoint.jpg
* * *
Matt Macchiarolo
www.townpeddler.com
www.wolverine4wd.org
http://wolverine4wd.org/rigs/macchiarolo_ml.html
III <----------@***.net> writes:
> Would you believe the '02 Factory Repair Manual has it pictured:
>http://www.----------.com/03TJCV.pdf
As does my '00 FSM, but as we're talking about rear driveshafts, Bill, you are
again grasping the irrelevent. Would you believe that every TJ has a CV joint
in the stock front driveshaft, and NO TJ from the factory has ever had a CV
joint in the rear.
Picture of a stock rear Rubicon shaft:
http://www.geocities.com/basscraft.geo/slipjoint.jpg
* * *
Matt Macchiarolo
www.townpeddler.com
www.wolverine4wd.org
http://wolverine4wd.org/rigs/macchiarolo_ml.html
12-31-2003, 09:05 AM
#58
Guest
Posts: n/a
Re: Lift & Driveline problems
In article <3FF246C3.7B6E3D82@***.net>, L.W.(=?iso-8859-1?Q?=DFill?=) ------
III <----------@***.net> writes:
> Would you believe the '02 Factory Repair Manual has it pictured:
>http://www.----------.com/03TJCV.pdf
As does my '00 FSM, but as we're talking about rear driveshafts, Bill, you are
again grasping the irrelevent. Would you believe that every TJ has a CV joint
in the stock front driveshaft, and NO TJ from the factory has ever had a CV
joint in the rear.
Picture of a stock rear Rubicon shaft:
http://www.geocities.com/basscraft.geo/slipjoint.jpg
* * *
Matt Macchiarolo
www.townpeddler.com
www.wolverine4wd.org
http://wolverine4wd.org/rigs/macchiarolo_ml.html
III <----------@***.net> writes:
> Would you believe the '02 Factory Repair Manual has it pictured:
>http://www.----------.com/03TJCV.pdf
As does my '00 FSM, but as we're talking about rear driveshafts, Bill, you are
again grasping the irrelevent. Would you believe that every TJ has a CV joint
in the stock front driveshaft, and NO TJ from the factory has ever had a CV
joint in the rear.
Picture of a stock rear Rubicon shaft:
http://www.geocities.com/basscraft.geo/slipjoint.jpg
* * *
Matt Macchiarolo
www.townpeddler.com
www.wolverine4wd.org
http://wolverine4wd.org/rigs/macchiarolo_ml.html
