vibration

Hello, I have a 2004 XJR with a vibration. It starts at 50mph and clears up just under 70. It was first thought to be cupped tires so they were replaced. That wasn't it. I have seen many posts on the internet where owners had many things adjusted or replaced but have never read where the problem was fixed. The vibration feels like it comes from the drivetrain. Not the steering wheel or rear of the car. I'm told it is not transmission internal and moving the colored/weighted nut around the end of the driveshaft didn't change anything. I had a LS Lexus with a vibration and after the dealer went through the whole car with no answer, a nother garage mechanic said tranny mounts, cleared it right up. I'm told that this is not the case here. So, does anyone know of a solution to what seems to be a fairly common problem? How many center bearings have gone bad and would that produce this effect. How about the rubber connectors at either end (the name escapes me.) More symptoms are that the vibration is there at 50 regardless of rpms. There is a squak or chirp when the transmission shifts at 50mph and the vibration starts. This is only under strong acceleration. Any and all help would be greatly appreciated.
Also, if I may, I have a "air suspension fault" indicator that come on when it is cold out, like 34 degrees and below. The suspension seems to work just fine otherwise with no effect to ride or ride height. Turns off after the outside temp rises. Anyone come across this issue? I assume it's a sensor.
Thank you, Scott

Can the vibration be reproduced with the car on a lift? The guibos are pretty trouble free if not visibly cracked, but make sure the bolts are tight. It seems that the standard XJR wheels bend fairly easily. (have seen several) Have a really competant tire place check the wheels AND tires for OOR, and out of true, and have them correctly rebalanced. 50 to 70 is the "typical" speed for tires to be felt, so I would look really hard there first. Also, what caused the tires to cup in the first place? Worn suspension parts could lead to mis alignment, and with wide tires....maybe you feel the "scrub"

Hi Jesse, I have the 20" Sepang wheels. They have been checked and there is very slight imperfection in a couple of them that the wheel expert claims wouldn't be felt the way I have described the vibration. One of the wheels had been damaged and repaired including some welding, before I owned. Expert said that wheel rolled out within tolerance.
The tires turned out not to be cupped at all according to Michelin. They were said to be cupped by Jaguar mechanic, my mechanic and sears techs where the Michelins were replaced under warranty and old tires sent back to Michelin. I couldn't feel the cupping myself. Not visible to the eye. I suspect that the vibration felt to them like one that results from cupped tires and they made assumptions. Jag mech said cupped wheels before we got on the road. The new Michelins have been on there for10,000 miles now and look like new. No uneven wear. I did spend the extra to have the tires road forced balanced. Wether it was done right or not??? It made no difference.
I have not tried 50 mph on the lift. Bolts have been checked and all is tight.
The "vibration" I'm trying to describe isn't a brrrmmmmm steady one but more like a harmonic brrmmm - brrmmm - brrmmm at a frequency that makes the veteran transmission guy that drove the car for near an hour one day feel it is in the drive train and not a freq that would come from a spinning wheel diameter but the higher freq of a smaller diameter, drive line.
This is why I'm back on the driveshaft and components.
Thanks again. The internet and forums certainly have changed problem solving. I appreciate it. Scott

I talked with mechanic today and he told me that I cant put car on lift to try 50mph. Traction control and abs won't let the car do that. That sound right, anyone. Thanks

You can't put a car on lift and run to 50mph. Seen some try it but the vibration could possibly dump it. It's possible the traction control and ABS can induce ignition cut-out. Did the vibration start before or after wheel repair? If wheel was repaired from damage from hitting something, has the suspension been looked at? The bushings can come into play, but have they actually test drove the car as all repairmen should before assessment to what is going on. Since it only occurs on heavy acceleration, maybe driveshaft loads up and vibrates. Could be motor mounts. Possibly even struts?shocks, but they would produce cupped tyres. So, I hope you can find someone who will actually try to find it.

If it is a "faster than road speed vibration" How about a quick test with removing the belts? Clearly, don't drive it like that,but a short rev to whatever RPM it happens at and hold for a second or two. I have seen an XJR where the blower drive belt was slipping and found the drive belt tensioner was slightly loose. Otherwise, it is a Mercedes trans, so perhaps a MB oriented person might have some input.

The one repaired wheel was that way when I bought it. I dont know where on the car it was when damaged. But I'm assurred :highly_amused: that its not causing this vibration. I dont believe this vibration would cause the car to move off a lft. It is very suttle. Most people don't feel it. As far as bushings go, one xjr owner said that a vibration that he had, explained to my mechanic so I don't know if it was the same, was caused by the top bushings on the front struts. But mines not in the steering wheel. It comes up through the car. I have read other posts where there was a vibration that came on at 50-70 and they described how wheels were changed, mounts changed, tires changed, etc under warrenty with no improvement. Its an illusive problem for sure. I've been told that the speed sensative steering is just that, sensative. So maybe a bushing that can't be felt in steering wheel?? The vibration comes on at 50 regardless of acceleration or rpms.
Thanks for all the help, greatly appreciated, Scott

I have another ideer. Check that the driveshaft is clocked properly. I am pretty sure it is still 2 pc shaft, if so, look at the positions of the bolts on the guibo at the trans and diff. Maybe someone got re assembly off by a spline. Also, look for missing balance weights (shiny spots where something was...) on the shaft. I was told of a method where someone attached a large hose clamp to the shaft, and rotated it (Trial and error method) on the shaft until the vibration was minimised.. If that were to be the case, then there are driveshaft shops that can re balance the shaft properly.

Hi Jesse, Yes the drive shaft is 2 pc. We have looked at it. There doesn't seem to be any signs of missing weights. I haven't looked into the possiblility of clocking. I will. As I mentioned earlier this Jaguar drivetrain is in part balanced with differently weighted anodized nuts that go on the bolts at the rear guibo. We moved the one that this car has to different bolts with no change. I'm now leaning towards center bearing or tranmission mount. I do have that air suspension fault indicator that come on when outside temp is cold and wonder if that could play into this issue in some way. As I've said it does not appear to effect ride or ride height and goes off when temp rises. So it's not based on a broken part. I found a place that will rebuild the drive shaft for $300 and cover shipping both ways. I just have to get it out of car where I can have car sit for a while. I'd think it to involved a job to do in the driveway.
Thanks again for the interest and help. Scott

Check the u-joints for the drive shaft and both rear axles.Flex the u-joints to see if there is any binding or looseness. Is there any play in the joints? Are the bolts attaching the axles to the differential all tight?

Look at the parts book at the transmount and differential. Some cars have a problem with harmonic vibration and will havve what looks like a lever with a weight attached extending from it to cancel the vibration.