I have a 2002 Jaguar Vanden Plas with 140K miles. I am getting a ride vibration above 50mph. It will smooth out at various speeds but it is present 90% of the time. The mechanic has narrowed down the vibration to the back right. On a lift the back right wheel can be seen moving up and down at high speeds.

I have replaced the center support and drive shaft. The back right Axial and U Joints. The back left U joints were replaced a few years ago. The car has new Michelin tires and an on car high speed balance. There has been talk of bad bearings in the back right but there is no normal noise associated with bearings that are bad.

Any suggestions?

 

Have you tried swapping the rim and tire to a different position?

 

Casey.....you have checked the most likely probables but one.
Has your mech. checked the condition of the diff output bearing?
Grab the wheel at 12 o'clock and push it in and pull out....any movement here will determine the wear of the bearing.
Better still to set up a dial indicator on the inner drive shaft flange...any movement more than 1.5mm will necessitate a bearing change.
Michelins are geting as bad as Pirellis to balance properly.
I assume you have standard 16" rims?
Have the wheel tyre combo dynamically balanced off the car and have the balance weights placed only on the inside of the rim.
Have the rims checked for 'runout'.
Make sure the UJ's are properly lubricated.
Have the outer wheel bearings been checked?

 

Yes.... did not help

 

Thanks... I will check in with the team forming around this problem in the morning

 

Well the diff output bearing test you suggested passed as well as other suggestions. They also temporially put 4 new wheels on as well. After contacting Jag who recommended adding a washer from where the axial meets the wheel (or something tonthe efect), the next step recommended to me is to replace the entire rear differential. Getting estimates now.

 

ive noticed this as well on my car, except the vibration only occurs at 50-60 mph

 

Tell you what ... take the wheels off both sides, put the lug nuts back on and run the test again. Is the right rotor still bouncing up and down? If not, it is the wheel/tire or the way they are mounted, if yes then they are fine and you have to look to the mechanicals.

 

I remember a TSB from Jaguar who spent a great deal of time and enrgy tracing mysterious vibrations.
IIRC, you have your car fitted with Michelins....as i said before, these are notoriously difficult to balance as is Pirellis.
The tyre casings are not manufactured as well as they used to be.

Before spending mega bucks I would be demounting the tyres and switching to different rims, then have them Dynamically balanced off the car on a proper computerised tyre balancer.
Once you have elminated the tyres as a possible, you can move on to other areas.
We have this problem locally with owners who insist on Michelin or Pirellis and swore black and blue they were not at fault.
I eventually persuaded one guy to switch to Yokohamas, the same as I run and the mysterious vibes up and dissapeared.

We have found the exact same problem on a club members X350....the same 'fix' was applied.....end of problem ;o))

Have you had the disc rotors physically removed from the car and cleran and check both mounting faces for a build of rust and crud....the mounting surface must be spotless and lubed with Kopr Slip or some such before remounting and check the disc faces for 'runnout'.
Have the bare rims been checked for any physical 'runnout'?

 

Took the wheels off. Ran the car up and the vibration is still there. I actually went to the shop today and took it for a test drive since replacing the drive shaft. The vibration is different. Occurs between 50 and 60. Above 60 it is still there but I am guessing the higher speed smooths it out. I understand what your saying about the tires.. I think they are well balanced.... They did run the car with another set of rims and tires... Same result.

 

I am very curious what the source of your vibrations is , i seem to have the same issue after a diff rebuild.

Is there a rumble sound when it vibrates , like a deep bass tone ?

 

Hello Casey,
I have been going through some old notes concerning this.
As you mentioned, all this strated with drive shaft replacement.
On the Xj-L as with a standard wheel base XJ8 the prop shaft is a two piece affair mounted with a centre bearing and a 'Jurid' coupling (the big black doughnut type things) at each end.
When the prop/drive shaft was replaced, was the whole system replaced or only one section?
According to my notes, there is a right way and a wring way of mounting these.
The centre bearing mounting can be missaligned and must be checked with a mounting jig.
The Jurid couplings must always be re-connected the same way they were undone.
If replaced, they have matkings so that they go in the right direction and position.
Missalignment of all three connections or not being re-attached correctly can creat a harmonic vibration.
If the Jurid couplings have stress cracks showing, they must be replaced and they can only be bolted up correctly one way and must rotate in the correct direction.
A Tipex mark is applied to the coupling so that it's bolted up the same way it came undone.
These can quite often cause a vibration that is often attributed to other causes.....worth checking.

 

Have you checked the lower knuckle bearings? Mine went out on the right rear and it was vibrating also. Cheap fix and you have to use a pry bar to check. Also just because the ujoints are tight does not mean they are good. One can be binding and cause vibrations also.

 

Yes. We replace the whole drive shaft. It is properly aligned. We even tried not aligning correctly and took it for a test drive. No noticeable difference.

The diff seems like the next step but have you heard of a bad diff that didn't make any noise? It seems the diff replacements that I read about are noise related. Using a stethoscope while the car is up in the air and running there are no noises related to the diff. But you can feel and see the vibration on the cars frame.... The bearings seem ok as well but I'm not sure how you would know without a noise. $2500 for the diff rebuild. It will really stink to replace a good one....

 

Take of the half-shafts , and try with only the diff ?

 

Update... We removed the rear axials and ran the car up.... Smooth as silk.. So can't be the diff... You can see the back right wheel moving up and down at high speeds. We moved the back right axial to the back left. Test drove the car and the vibration moved to the back left. Must be a bad axial? No replaced the axial but absolutely no change. I'm lost now... The wheel bearings are good.... Any ideas?

 

Hope this doesn't sound too off base but I have had similar problems with other cars and it turned out to be the torqe converter. Might try running in a lower gear where the converter won't engage.
Just a thought, I know you have had many suggestions. Hope you find the problem. I know sometimes vibrations are hard to find (kinda like sqeaks).
Dave

 

So you could feel the vibration on stands , with the axles still mounted ?

Did you put the stands under the jack points or the wishbone ?



To rule out a bad axle , switch axles one more time (as you have one new now) , sometimes the vibration appears to be on the other side as it actually is.

 

when im cruising up to highway speeds, the vibration occurs between 50-60 mph, then when i manually shift the car into 4th gear, the vibration at those speeds no longer continues, any thoughts? and maybe this will help your problem as well

 

So, at the *same* road speed the vibration disappears if the transmission is shifted? Am I understanding correctly?

Well, in shifting gears you've changed engine RPM. Seems to me, then, that your problem isn't related to anything turning at a given road speed: wheels, tires, axles, propshaft/driveshaft, u-joints....anything aft of the transmission output.

Cheers
DD