I recently purchased a 2002 xk8 convertible with 38500 miles. At around 70 mph it starts shimming. Now the odd thing is, at a sustained speed, say 75 the shimming stops and then starts again. This is on the interstate with a good road surface. Anyway, I took in in .and had wheels balanced and front end aligned then road tested it and still had slight shimmy but very much improved. I would think with a relatively low mileage car, bushings would not be worn. I should note that this is my first Jag and i'm not sure what to expect in terms of ride but am somewhat disappointed in ride comfort. Any feedback would be appreciated. Thank you in advance

 

Rubber and foam can wear, but they also can breakdown over time.

Upper shock mounts can compress, lowering the front, giving it more camber which can give more shimmy feedback to the steering wheel.

The other question is how old are the tires? Balancing assumes that the tires are round and true. If the tires are not round and true (for example, have flat spots from sitting long periods), they will balance fine but can induce a harmonic into the suspension.

 

Same issue @ same speed with my '99. Tires are worn evenly could use replacement, however not looking to replace tires yet. Balance and alignment usually do not achieve the same results on worn tires as compared to new. Tire pressure is very specific with these cars. The place card located under lid in console states 26 and 28 lbs. Low per todays standard however it does move the vibration out of my 70 mph driving range... Rich

 

thanks for the feedback. Tires are new, less than 300 miles. I will try reducing tire pressure to 26 psi. If that does not work will look at shock mounts.

 

Did you get a good look at the old tires to see if there were any unusual wear patterns?


Worn upper shock mounts usually result in inner tire wear.


The distance from the wheel center and crumbling foam near the upper shock nut are the best indicators for the need for new upper shock mounts.

 

Foam is definitely crumbling. Will replace mounts with rubber. So far, wheel balance. frontend alignment, will reduce air in tires to 26 psi. Wlil let you all know results next week. Thanks much for your help.