2004 XJ8 64K miles. Brand new Mich 235/50/18"tires. Car has drive train vibration, seats and body vibrate under acceleration and at cruise speed seems like a rumble, but not all the time. Can feel vibration in the steering wheel at 50 mph, almost like the power steering pump is out of balance. Tires were re checked for balance and they are perfect. Getting more frequent, car is smooth at lower speeds. Seems like a bad U joint?

 

U joint would be my next spot to check. I myself have been getting a lot of bad CV axles in our area (not on Jags as we do not have too many around), but a CV joint should work for a long time, unless it allows water/dirt/contam inside. Of the bad joints we have had lately, majority of them have split boots, but a few have loos boots that went through water at some point causing it to become washed out, and damage the internal parts of the joint.

Get the vehicle in the air with a driver inside and bring to 20, 30, 40, 50 mph to determine the worse harmonics. I know the X-type has AWD/option for it, but unsure of the XJ8. Either case, it appears you have a bad joint, or a bad mount causing the drivetrain to come out of alignment.

Hope this helps!

Ryan

 

Thank you very much for your answer. The car is going up in the air tomorrow. I didn't know you could run the car while it was on the lift but I will do that. Great idea.
Thank you
Regards
Bill

 

Sounds good. Keep me posted on what you find. Before you lift it like that, make sure there is no air ride, and if there is to turn it off if required per lifting procedures.

 

Some info for you.

bob gauff

 

"optimum vehicles level of refinement" huh?

 

William,

Just as a reference check, were those tires changed to correct this problem? That is, did you have the problem before you replaced the tires?

I had a similar issue that my tire shop got onto in short order. One badly bent wheel and another slightly bent.

 

I put the car up as you said and ran it. It was the drive shaft center bearing and joint making the vibration. Thank you again.
Regards
Bill

 

No, tires were warn and needed replace. The wheels were perfect and balanced with light weights.
Thank you.
Regards
Bill

 

I feel deep base like vibration in my xj8. at first I thought some body had base turned in next lane. well is that something similar like your condition. What was your solution after finding bad bearings. And what did it cost you? did it solve the problem?