Hi all,
When looking for a replacement for my S type R I inspected various SV8 and XFR 2008-2011 models. All cars that I inspected seemed to have really uneven tyre wear from the inside of the tyres out. The inside being badly worn. I'm wondering why this is so previlant with the 20" wheels. I replaced my cars tyres the other day and took the car to have a wheel alignment and camber/toe adjustment at Sydneys best suspension specialist and was told there doesn't appear to be any camber adjustment in the rear of these vehicles. They were able to adjust the rear toe but not the camber. The front seemed to have both adjustments. Does anybody know any more about this or have any futher light to shed on this subject??
regards
Joe

 

Yes, we have discussed in the various Jaguar forums the lack of rear camber adjustments. It is shame that some manufacturers choose to save a few bucks and eliminate such important setting. I used to race cars and still have my alignment tools. When I checked my various XK, XJL and XF rear cambers I generally found them to be -1.5 on the average. That is actually a bit too much negative camber (top of wheel leaning in, bottom out) which is causing the inside tire edge wear. On the other hand the factory setting usually show much less negative camber on the front wheels. When I tried to put more negative camber on my front wheels, the adjustment maxed out at -0.3 degrees.

The factory is likely setting up the cambers to provide a more planted rear grip under cornering as it is safer for the average driver. You are less likely to spin out if going into a corner too fast. Combine the larger rear negative camber with 20" wheels and you get inside tire wear. 20" low profile tires need to be planted flat on the pavement for ideal operation. So, under straight line driving they are NOT planted flat because the wheels are slanted out. But, under moderate to heavy cornering the car rolls over and plants those tires flat. Thus, the -1.5 camber is good for cornering, not ideal for light or straight driving.

The one minor adjustment that is possible to produce a more even thread wear is to give the rear wheels a slight toe-in.

Albert

 

Good advice. A little extra rear toe in can reduce negative camber wear and assist cornering grip. Also, Jaguar engineers set alignment specs with British roads in mind. Cornering frequently at high speeds also evens out rear tire wear induced by camber. This is the norm in the UK.

By comparison an Alfa 164, which has fwd, specs up to 2.4 degrees negative camber for the front suspension. Cornering is excellent but tire wear is awful. However, camber wear results mainly from straight line motoring North American style. If you corner a lot and very hard then negative camber is your friend and tire wear will be more even. Rapid, but even!