I was getting ready to do the remote top and took off my front tires. I had a new set of Perelli's put on about 4000 miles ago. I had the alignment done at the same time, the place had a brand new state of the art machine??? Well, when I took the tires off I noticed that on the left side the inner edge was worn to the cord about 2 1/2" on the right is was worn on the inner edge but not as bad. I couldn't tell from looking and I had some vibration but because of the RP coding all the time I thought that was the vibration. Do you think the guy messed up or should I check out something underneath like bushings ? Thanks Guys

 

Hmmm could be either of your suggestions, you have to assume the guys knew what they was doing and set the tracking correctly, but then again if the bushes have worn whatever they set up was a waste of time. Will be worth giving your bushes a good checking over.

 

Thanks Tony, I'll take a look at them.

 

Pulled off all 4 tires, the bushings all looked OK with the weight off all fours. I guess I'll see how good the guy treats me when I take it back and show him my tires.

 

This happened to me before as well ... it even manifested itself into a slight vibration problem, btw 40-60mph. It started when I replace the rears with BFG with the front still with the Pirellis.

3-4 months ago, I changed the front with same BFG and the uneven wear issue is no more .... The bushings look ok. I still find it hard to believe that the uneven wear is attributed to different treads, but I can't explain it any other way ......

Zmann - let us know what you find out pls.

 

WOW! interesting, I am going in next week to have it checked. I'll let you know,glad you mentioned it before I go back and bite the guys head off LOL

 

Also, does it pull to either side when stopping or accelerating?

What are your tire pressures?

 

No,it doesn't pull on either. Tire pressures are 32 front and 34 on rears. I do notice now that I have a concern and have looked more closely that the tires don't seem to be flat with road contact. they seem to hit more on the outter edges.

 

Sounds like you need to get your camber checked

 

With being flat on the road, if the tire suggests more PSI, do you go with the car spec or the tire spec? just wondering.

 

In my opinion, get close to the spec for the car. I noticed in the XK8 manual, there are two specs for the car. One lower for comfort and one higher for speed. I choose to be closer to the one for speed. Maybe the tires will last a little longer than the lower pressures for comfort.

 

I just put near 9000 km on with no uneven wear and I kept mine at 35lbs both ends. Mine are P zeros and fairly sticky.

 

Alignment on these cars is tricky! Be sure you have someone with experience on Jaguar.

 

True. 2 good places turned my alignment away because they didn't have the special gear to do the XK8 properly. If I'm not mistaken they need to load the front end and then do the alignment.

 

Some tire shops will do a free alignment check. Call around to find out. Be sure to get a copy of the printout, because it should show the actual measurements vs. the specs.

 

There is nothing mystical about XK8 alignment. Camber is not adjustable, and as springs sag, the negative camber increases. This results in premature wear of the tire on the inside edge.

Toe in is the only easy adjustment to set. It can compensate for excessive negative camber up to a point.

Finally, caster is adjusted by removing the long pin on the upper arms, and replacing the shims in a different order; either to push the upper A-arm more forward (for less caster) relative to the lower arm; or pull it rearward.

My alignment guy works on all sorts of NASCAR and SCCA projects. He is pretty much old school and does everything using unsophisticated [read: non digital] tools. He adjusts the settings for the crown of the road and the grade on the right hand side... where we in the US ride. He also says that rotating tires is the best action you can take to prevent premature camber wear. If you cant rotate beause of different staggers... sorry.

 

That was very informative. Thank you very much. I suppose I could replace the springs....right ? and not have to go thru all that shimming and then it would be set for a while. Thanks again

 

When I bought my xkr it had 255/45 tires on both the front and back. I have learned there should be a stagger with 245/45 on the front. Is there a big problem keeping the same size tires on both axles? I know the speedometer will be off a bit (1.3%) I was thinking of keeping them the same to be able to rotate them as they have the same where pattern on the inside of the front tires.

 

The lower control arm bushes were a constant problem with the early XK/XJ cars.

Here is a TSB from 2003

bob gauff

 

That TSB also provides a neat solution for pressing out the bushing.

Bob,

Sooner or later I am going to capture all your TSB's.

Thanks!