I was driving it again yesterday and noticed it's at it's worst at 55mph. I was feeling all over the drivers bay floor and felt on the passenger's side of the shifter column while driving at 55mph, and i'm pretty sure the shaking is coming from the middle of the car.

I've yet to ride in the back while it did this, but it feels like the front-middle of the car. That could indicate U-joints since they run through the middle of the vehicle possibly?

I also noticed that at 50-70mph (especially 55-60mph) pulling off the acceleration seems to make it worse, like it shakes a lot harder or what not. The shake doesn't change speeds at all, it just seems to shake harder when just coasting at those speeds. When acceleration is applied, it seems to ease up a bit, still shaking, but a lot less intense.

I know this car has original everything from wheel bearings/u-joints etc.

 

I bought a 2001 XJ8 a year ago with 82,000 miles at the time of purchase. The car made the same grumbling sound and you feel a vibration in the steering wheel, particularly at 55mph. The sound/vibration was particular present between 50-65 mph (55 being the worst), with less noise problem below or above this range). I tried the cheap fixes like a wheel balance and alignment, but the bottom line is that the bearings on these cars die around 80k. I am not a mechanic and don't know you're car, but I am a betting man and I'll bet my pink slip (on the XJ8, not the XK8) that you need to replace your front wheel bearings. Once you are in there, you are probably gonig to need to do some other work. I did the front shocks, struts, bushings and dampers-- and you're going to have to do another alignment too after the wheelbearings. The total bill came to around $900.00 at a Jag Specialist (I'll on the main franchise dealer with their insane labor rates).

 

Thanks. Yes, my wheel bearings have never been replaced, could very well be the front wheel bearings, it's definitely in the front-middle of the car. As i've read over the past 3yrs on here, wheel bearings through 70-100k seem to be troublesome as you stated.

I don't plan on keeping this car another full year to be honest, so I'm not going to invest that much jack to do the whole suspension etc. My tech knows this car very well now (hah) and has worked on foreign cars for 40yrs. I'd just like to get the crazy shaking subsided for now. I'll have it checked out at the end of the month.

Like I said, whatever it is, got a lot more apparent when I put thinner tires on my car. Makes complete sense, I went from 225/60/16 to 245/35Z/20 a lot less sidewall to absorb the shaking.

 

If the vibration is felt in the steering wheel the problem is up front if the vibration is felt where your leg meets the seat the problem is in the rear with the exception of the universals in the driveshaft. You have 2 universals on the driveshaft, and a total of 4 on the rear axles 2 on each side. I am certain that you have a driveshaft that has either sliding joint or a one peace. I am not sure if the car comes with a flex joint. If I were you I would get the car on the lift and check it all. This will mean rotation the shaft (little at a time) with a little pulling and tugging each time you may find it. This applies to a 95xj

 

This is for a 1998 and on, it shows a center bearing that I was unable to capture the last time. It could be the problem.

 

Thanks for the info but unfortunately my whole car shakes so of course it won't be diagnosed to it hits the shop. Everything shakes, The whole driver's seat. The steering wheel, the back seats, the passenger's seat actually shakes as well. a nice wobble from right to left.

Will have it checked out soon enough, thanks for the advice i'll try to determine more on location of the culprit if possible before it hits the shop.

 

without reading the whole thread, ,make sure to check the jurid couplings at the front and rear of the driveshaft. Theyre rubber couplings between the shaft, diff, and trans. they function like ujoints. when the front 1 goes vibration is worse on accel, rear 1 on decel. look for distortion and cracking around were the bolts go through the steel sleeves in the coupling. I just had 1 so bad on a Stype the flanges were hitting each other on acceleration

 

I know this was a while ago, but did you get it sorted? my guess it is the tail shaft out of balance since new.
Regards
John

 

what was the outcome with this thread...my car does the same...I had all my front bushings and balljoints replaced as well as new rotors and brake pads...in addyion to the vibration at 50-70 It also feels like my brakes stick when I start breaking...

 

It's a shame there doesn't seem to be a solution posted. My 2001 has 4 u-joints, 2 on each half-shaft, but none on the prop/driveshaft. Could the problem be caused by the center bearing adjustment ? My 1986 XJ6 had a center bearing (for driveshaft) and it was sensitive to side-to-side adjustment, or maybe the bearing is sloppy itself. I haven't heard much about this on the X308, but it sounds like maybe it could happen. The jurids sound like a possibility too.

 

The sad part of using a forum to resolve a problem is that the solution is not always posted.

 

I had the same problem when I just bought my XJ8, the solution was sway bar bushes (anti-roll-bar); very cheap solution, probably 20 dollars and half hour job. It still shakes a little (90-100 mph is good), but new wheels,ball joints, lower bushes and discs+pads didn't cure it yet.
Upper joints and bushes still to be tryed.

 

I would suggest checking your motor and transmission mounts. Replacing both fixed my steering wheel shake from 45-55mph