Just a thought and I know this is a given but are you sure "ALL" your tyres are mounted correctly w.r.t rotational direction. I had a friend who got shakes at high speeds and found out after getting his tires rotated that his Z rated unidirectional tires were mounted wrong and turning counterclockwise while driven.
________
medical marijuana states

 

Steering axis inclination variances shouldn't effect the conditions you're describing. Again my question would be, did you have your rims checked for trueness?

Also as I mentioned, Pirellis are not the roundest tires out there.

 

Here's the thing. I have a road force variation machine, and with that being said. the set up make's the out come. I balanced my own wheels and still had the shimmy at speed. I put the wheels back on the machine and found out that the wheels were not running true. The adaptors that are normally used for most cars will not work on ours. It takes a special set up. It turns out the adaptors that are used work on 90% of the cars out there but our cars have a special bolt circle. I guaranty if you bring it to me I can get rid of your problem, with what I know now. I also know that a tire shop may not have the right set up and will cause you more harm than good. call me if you are in so cal and I will fix it or it will not cost you one penny. sound fair?

 

XKR Brian: I've had the wheels off of my 2000 and I don't have any adaptors. Are you using an after market rim?

 

I think he is talking about the adapter used to mount the wheels on the balancing (Hunter 9700) machine.

 

yes I am talking about the "set up on the (hunter 9700) balance machine. I did this myself on my own car and found out even though the wheel may appear to be ounted straight it may be way off balance when done if the set up is not right.

 

Alas, I don't live in California. I don't even live in the US! I do appreciate all the good feedack I'm getting though. The steering wheel shake is seriously detracting from the experience of driving this great machine. It can be felt occasionally at lower speeds but it becomes semi-violent at 65mph. It seems to be worse on a descent, and it braking at high speed also exacerbates the issue. This final point is leading me to believe it's probably a suspension/front axle or brake disc/rotor problem.

 

Resolution at last! I had the wheels balanced in a different tyre shop. They spotted a 10 gramme disparity on one wheel. They told me that for most cars 10 grammes would be nothing (50-60 would be more the norm), but Jags are "easily upset" apparently! Took the car out for an extensive roadtest last night and the steering wheel shake has disappeared! Incredible. Thanks for the advice re double-checking the balancing etc. before trying more costly items.

 

excellent raheny, glad you got that problem fixed. Never hurts to get a second, or even a third opinion when human error (adding weights where the computer says to do it) is required.

 

dont mean to burst your bubble, but I just read your second to last post and cant help but feel you still may have a problem. The only way you will feel it at low speed and make it worse when you hit the brakes is if you have either warped rotors or something loose in the suspension. You may have fixed the freeway shake but keep a look out for the other 2 concerns to raise their ugly heads. This too is easy to diagnose, so if and when the problems arise chime in and I will tell you where to look

 

good point Brian, if she shimmy's when applying the brake...high speed, low speed...whatever, look to new rotors.

 

Be careful, rotors rarely warp (been around cars for a long time, only seen warped rotors on race cars), cheap pads overheat easily and then deposit molten material on the rotors and the pad jerks when passing over it. The problem is the pads, not the rotors. You can look at the rotor and see teh streaks on it when there is pad deposition. Good pads will make rotors look very even in color and smooth. A brake that is pulsing can be stopped by changing to good pads. They will remove the deposition on the rotor and keep it clean. When tallking cars like XK8's and R's, the pads should be high performance and high quality by good companies such as Pagid, Brembo, Mintex, EBC, and Hawk. I have not had problems with cheap rotors causing problems, just pads.

 

I wonder what the problem actually was...we may never know (June 2009)

 

I know this is an ancient thread, but I just read oldmots' comment above about rotors not warping. That's probably true on these XK8s because they are pretty thick rotors. However about 8 or 10 years ago my company used Chevy Malibus for the company cars for the sales reps and managers. We had about 20 of them at my office and every one of them suffered from warped rotors. It usually happened after the first tire rotation when Jiffy Lube would over-torque the lug nuts with the impact wrench. 1000 miles later the steering wheel would shake when the brakes were applied, and we would take them to the Chevy dealer for repair under warranty. I was in charge of the fleet vehicles at the time, and the Chevy dealer service manager kept telling me that it was because the lugs were being over-tightened and that it shouldn't be covered under warranty. He covered it anyway since we gave him so much business, but the way I saw it it was a design flaw and the repair should not only be covered, but they should replace the rotors with ones that wouldn't warp.

 

With a brake problem this Summer I took the OEM rotors from a '02 XK8 with 53k miles to a shop to have the 'glaze' turned off them. They were so warped that they could not be trued within specs. I stood there and watched the tech mounting the rotor on the lathe and it certainly appeared to have been done correctly. Not that I am an expert but I have done that myself long ago and far away. New rotors and pads fixed my 'pulling' problem.