Re: TJ Vibration: rear axle bent?
 

I have. Steve Seppala from this group did it to his YJ. There was
runout on Steve's. I'll bet there is a slight runout on his too which
could be the vibration. Even just the shaft bend could set up a
harmonic at a certain rpm.

Mike

Earle Horton wrote:
>
> The axle forging could be bent, but if the ends have been machined straight,
> you wouldn't have a problem. I don't think I've ever seen one like you
> describe though.
>
> Earle
>
> "Justin M" <xtexatl@gmail.com> wrote in message
> news:1163281207.917447.180920@b28g2000cwb.googlegr oups.com...
> > The thing that's interesting about this is it doesn't show up when I do
> > that. It's technically straight -- but there's a bend in the middle.
> > The tire doesn't wobble, but you definitely can see it in the axle
> > itself once it's out of the tube and slowly rolled. (I put it on my
> > workbench and rolled it, and it bobs up and down).
> >
> > Now I just have to find someone local with a hydraulic press. :)
> >
> >
> > Mike Romain wrote:
> > > Wow.... That's a lot of work to find a bent axle...
> > >
> > > That should show up in the wheel if you jack it up and spin it, more
> > > than enough to vibrate.
> >
>
> --
> Posted via a free Usenet account from http://www.teranews.com

Re: TJ Vibration: rear axle bent?
 

I have. Steve Seppala from this group did it to his YJ. There was
runout on Steve's. I'll bet there is a slight runout on his too which
could be the vibration. Even just the shaft bend could set up a
harmonic at a certain rpm.

Mike

Earle Horton wrote:
>
> The axle forging could be bent, but if the ends have been machined straight,
> you wouldn't have a problem. I don't think I've ever seen one like you
> describe though.
>
> Earle
>
> "Justin M" <xtexatl@gmail.com> wrote in message
> news:1163281207.917447.180920@b28g2000cwb.googlegr oups.com...
> > The thing that's interesting about this is it doesn't show up when I do
> > that. It's technically straight -- but there's a bend in the middle.
> > The tire doesn't wobble, but you definitely can see it in the axle
> > itself once it's out of the tube and slowly rolled. (I put it on my
> > workbench and rolled it, and it bobs up and down).
> >
> > Now I just have to find someone local with a hydraulic press. :)
> >
> >
> > Mike Romain wrote:
> > > Wow.... That's a lot of work to find a bent axle...
> > >
> > > That should show up in the wheel if you jack it up and spin it, more
> > > than enough to vibrate.
> >
>
> --
> Posted via a free Usenet account from http://www.teranews.com

Re: TJ Vibration: rear axle bent?
 

Using some creativity (and an extra set of bearings), I was able to
hook the axle up to a drill and secure it down to my work bench. At
low RPM's, it is fine... it spins nicely, the hub doesn't wobble....
hit about middle speed, and the axle starts to wobble the work bench --
but the hub is still spinning but not moving up/down. A little faster,
and it started to resonate and finally broke free from the mount I
built, almost leaping off of the bench.

After getting my (much more math inclined) roommate to crunch some
numbers (it's nice having an engineer around sometimes), we determined
it starts moving around 50mph, and at 63mph, it starts jumping around.

I imagine the 35" tires are keeping the wheel on the ground due to the
weight ... but eventually the vibration gets bad enough where the wheel
starts to bounce.

Man. This was a long trip to get here.

The first time I looked at the axle, I didn't notice the warp. I was
using a piece of wood that I thought was straight. I finally went out
and bought a true straight edge, and it was obvious.

At least I got a lot of parts replaced that probably needed to be
replaced anyway (front bearings, u-joints, disc rotors and drums).

I've ordered new axles and bearings -- hopefully they'll get in this
week -- and then I'm off to find someone with a hydraulic press to push
the bearings on. And hopefully this will be the end of this adventure.

I'm also going to write a nasty letter to Chrysler about their "five
star" dealer that charged me $320 to find the vibration, only to tell
me it was the lift's fault. I fail to see how a 3" lift/35" tires could
warp an axle. I would expect it to be bent -- not "sag" in the middle
by a millimeter.

Finally, on the positive side... I now know tons more about the
suspension, drive-train, and steering system of the Jeep. Before I
started looking into this, I knew next to nothing. :)

j


Mike Romain wrote:
> I have. Steve Seppala from this group did it to his YJ. There was
> runout on Steve's. I'll bet there is a slight runout on his too which
> could be the vibration. Even just the shaft bend could set up a
> harmonic at a certain rpm.

Re: TJ Vibration: rear axle bent?
 

Using some creativity (and an extra set of bearings), I was able to
hook the axle up to a drill and secure it down to my work bench. At
low RPM's, it is fine... it spins nicely, the hub doesn't wobble....
hit about middle speed, and the axle starts to wobble the work bench --
but the hub is still spinning but not moving up/down. A little faster,
and it started to resonate and finally broke free from the mount I
built, almost leaping off of the bench.

After getting my (much more math inclined) roommate to crunch some
numbers (it's nice having an engineer around sometimes), we determined
it starts moving around 50mph, and at 63mph, it starts jumping around.

I imagine the 35" tires are keeping the wheel on the ground due to the
weight ... but eventually the vibration gets bad enough where the wheel
starts to bounce.

Man. This was a long trip to get here.

The first time I looked at the axle, I didn't notice the warp. I was
using a piece of wood that I thought was straight. I finally went out
and bought a true straight edge, and it was obvious.

At least I got a lot of parts replaced that probably needed to be
replaced anyway (front bearings, u-joints, disc rotors and drums).

I've ordered new axles and bearings -- hopefully they'll get in this
week -- and then I'm off to find someone with a hydraulic press to push
the bearings on. And hopefully this will be the end of this adventure.

I'm also going to write a nasty letter to Chrysler about their "five
star" dealer that charged me $320 to find the vibration, only to tell
me it was the lift's fault. I fail to see how a 3" lift/35" tires could
warp an axle. I would expect it to be bent -- not "sag" in the middle
by a millimeter.

Finally, on the positive side... I now know tons more about the
suspension, drive-train, and steering system of the Jeep. Before I
started looking into this, I knew next to nothing. :)

j


Mike Romain wrote:
> I have. Steve Seppala from this group did it to his YJ. There was
> runout on Steve's. I'll bet there is a slight runout on his too which
> could be the vibration. Even just the shaft bend could set up a
> harmonic at a certain rpm.

Re: TJ Vibration: rear axle bent?
 

Using some creativity (and an extra set of bearings), I was able to
hook the axle up to a drill and secure it down to my work bench. At
low RPM's, it is fine... it spins nicely, the hub doesn't wobble....
hit about middle speed, and the axle starts to wobble the work bench --
but the hub is still spinning but not moving up/down. A little faster,
and it started to resonate and finally broke free from the mount I
built, almost leaping off of the bench.

After getting my (much more math inclined) roommate to crunch some
numbers (it's nice having an engineer around sometimes), we determined
it starts moving around 50mph, and at 63mph, it starts jumping around.

I imagine the 35" tires are keeping the wheel on the ground due to the
weight ... but eventually the vibration gets bad enough where the wheel
starts to bounce.

Man. This was a long trip to get here.

The first time I looked at the axle, I didn't notice the warp. I was
using a piece of wood that I thought was straight. I finally went out
and bought a true straight edge, and it was obvious.

At least I got a lot of parts replaced that probably needed to be
replaced anyway (front bearings, u-joints, disc rotors and drums).

I've ordered new axles and bearings -- hopefully they'll get in this
week -- and then I'm off to find someone with a hydraulic press to push
the bearings on. And hopefully this will be the end of this adventure.

I'm also going to write a nasty letter to Chrysler about their "five
star" dealer that charged me $320 to find the vibration, only to tell
me it was the lift's fault. I fail to see how a 3" lift/35" tires could
warp an axle. I would expect it to be bent -- not "sag" in the middle
by a millimeter.

Finally, on the positive side... I now know tons more about the
suspension, drive-train, and steering system of the Jeep. Before I
started looking into this, I knew next to nothing. :)

j


Mike Romain wrote:
> I have. Steve Seppala from this group did it to his YJ. There was
> runout on Steve's. I'll bet there is a slight runout on his too which
> could be the vibration. Even just the shaft bend could set up a
> harmonic at a certain rpm.

Re: TJ Vibration: rear axle bent?
 

No pain, no gain??? :)


>
> Finally, on the positive side... I now know tons more about the
> suspension, drive-train, and steering system of the Jeep. Before I
> started looking into this, I knew next to nothing. :)
>
>

Re: TJ Vibration: rear axle bent?
 

No pain, no gain??? :)


>
> Finally, on the positive side... I now know tons more about the
> suspension, drive-train, and steering system of the Jeep. Before I
> started looking into this, I knew next to nothing. :)
>
>

Re: TJ Vibration: rear axle bent?
 

No pain, no gain??? :)


>
> Finally, on the positive side... I now know tons more about the
> suspension, drive-train, and steering system of the Jeep. Before I
> started looking into this, I knew next to nothing. :)
>
>

Re: TJ Vibration: rear axle bent?
 

RoyJ wrote:
> No pain, no gain??? :)

It's a Jeep thing. ;)

>> Finally, on the positive side... I now know tons more about the
>> suspension, drive-train, and steering system of the Jeep. Before I
>> started looking into this, I knew next to nothing. :)

Re: TJ Vibration: rear axle bent?
 

RoyJ wrote:
> No pain, no gain??? :)

It's a Jeep thing. ;)

>> Finally, on the positive side... I now know tons more about the
>> suspension, drive-train, and steering system of the Jeep. Before I
>> started looking into this, I knew next to nothing. :)