I just had my '03 XJ8 in the shop for a four wheel balancing and it took care of the shaking at 60 mph - mostly.

Now what I experience is a sensation that I'm driving on a bumpy road, kind of like a washboard, not too severe, just a little annoying. It happens at speeds in excess of 55 mph and never really smooths out, even at 75 or 80 mph.

I can see and feel the steering wheel vibrate up and down, I can feel my foot on the accelerator vibrate as well.

Like I said, it's not severe but still annoying. It doesn't seem to be a balancing issue, so I'm guessing it's either (1) a bad misfire (no codes, though) or (2) a suspension part or two (or three!).

Any ideas?

I would like to get to the bottom of this issue at some point, but for now the car is quite drivable, and when I try to demonstrate it to passengers they claim they can't feel it. I'm pretty sure it's not my imagination, and I'm just as sure that it hasn't always been doing this. I'm thinking (hoping) it's a bushing or something that can fairly easily be replaced.

The car has just over 89k miles on it and is in damn good shape!

Thanks in advance for any suggestions.

Mike

 

I would replace the shocks and bushings, if all the rims and tires checked out OK.

 

a lot of people suggest 'road force' balancing, this is loaded tire balance, not just spun up.
Try this first.
How do the front upper shock bushes look? I suspect it will have cats suspension - unless the dampers are leaking they don't need changing.

 

Thanks for the info -- but I don't know what load force balancing is, should my mechanic or tire shop know what it means?

The front upper shock bushes look original. I'll run out and take a photo and post it in a few minutes. Thanks again.



1st photo is passenger's side, 2nd photo is driver's side.

 

I had the same issue since I bought the car , about 2 1/2 years ago. I tried everything possible to solve it : changing all the front bushes (sway bar, wishbones, lower shock's) plus the ball-joints, new discs,pads. Balancing the wheels 20 times, new tires,new rims, nothing cures the vibrations. A week ago, when I changed the winter wheels with summer ones, I made 2 simple things, fixing the front bumper's under-tray,it was loose and the air stream makes it shaking, and tightening the wheel bolts in a circular pattern, one after one and not in star like it was recommended and used by the tire shop guys. All the vibrations are now gone , 0 th 100 it's perfect! One thing solved a part of the vibrations , changing the front sway bar bushes, cheap parts and easy to change. Worth a try!

 

When I got the car, the splash guard and the brake cooling tubes were missing -- I replaced them last summer (all except for the driver's side brake cooling tube which I replaced about a week ago). The vibration seems to be totally unrelated to those parts since it vibrated before and after the installation.

As for replacing bushes -- I think that's what I need to do. I don't like to do unnecessary things to my car (seems like the old adage, "if it ain't broke, don't fix it," is closely related to "leave well enough alone" and "take two steps forward, one back" meaning that there's a good chance I'll mess something else up! LOL).

However, if there's a good chance that changing the front sway bar bushes could solve my problem, I'm game! Now I just need to find the parts and make sure I have the instructions....seems to me there's a how-to somewhere on this site, maybe in the XK forum.

Oh yeah, does anyone think I should replace the upper front shock bushes that are pictured above? I'm not planning to replace the shocks since they don't seem to be bad (bounce test), but I could replace the bushes. Should I do so, or leave well enough alone?

 

The sway bar bushes are a half hour job, just 2 bolts each side to remove the brackets(but you have to remove the under-tray) . The rest of the bushes may be OK on your year and mileage. You can try cheaper things first or spend hundreds, it's your money.
Just try to suspend the front wheels and tight them in the circular way, these cars have the brake discs fixed and aligned only by the wheel nuts.

 

I will suspend the front wheels and tighten them as you suggest -- I'll report back after I do so. Thanks.