went to have the tires rebalanced and rotated yesterday and both rear tires need to be replaced . both are wearing/worn excessively on the inner half on both sides was told when i first got the car that the rear tires have little or no adjustment and find this hard to believe . after seeing this is there anything i can do to correct this on the rear tires ?

 

Rear alignment is done with shims that only a dealer is going to have on hand. They can be ordered but a full dealer alignment is probably your best bet. I caught an alignment special at a dealer some years ago that matched local indy prices.

Mine do not rotate. Sure the wear occurred while on the back?

 

I like what "test point" ask.

Since you say you have your tires rotated, are you sure the tires on the rear-----before you bought new ones-----are wearing on the rear?

Could be that the wear started while in the front. I was told that once a wear pattern starts on a radial tire , it continues regardless where it is--front or back. In other words, if your tires are wearing on the inside in the front and you then put them on the rear, they will continue to wear on the inside.


That may be an old wives tale, but it's a good thought and so far, since radial tires came out, it has worked for me.

 

SNG list the Half Shaft Spacer's for the drive shaft. They go between the drive axle and rear end. The bottom bolt on the rear hub has adjustment. I would think any shop that does 4 wheel alignment would be able to get it right. You may have to order a handful of the shims for them.


Wayne

 

The shims aren't exactly cheap so buying assortments gets pricey.

Unless the negative camber on the rear is gross, the likely cause of inner edge
wear on the driven axle is excessive toe-in. I think ... in any case, incorrect toe.

 

The shims are used to adjust the rear camber by lengthening/shortening the swing axles.

The spindle bolt connecting the control arm to the bottom of the hub has an eccentric flange which I'm pretty sure is used to adjust toe-in. That adjustment would most likely effect tire wear more.

However, our suspension is so friggin' stout, that if rear alignment goes out it's probably due to something being damaged or worn. Jumping through hoops for caster shims and/or toe adjustments may just be kicking the "repair can" a little further down the sidewalk. If your alignment is out, I'd first want to know "why".

Just my 2 cents. (and worth every penny! - lol)

 

What are your alignment numbers? This is something you should keep print out on for every alignment, before and after print outs. My rear camber is -1.6 on both rear wheels, I have normal even wear. I have them compensate with increased toe-in. Negative camber on rear or front shouldn't become a tire wear issue until nearing -2 degrees.

 

I took the car to a local shop several months ago and they would not attempt to align the car due to computer generated rear end results. They had the latest, greatest Hunter computer alignment system. They sent me across town, perhaps a half mile, (small town) to the other shop in town with the same alignment system.

Their system found the rear alignment within specs.

What's a Mother to do?

 

have never rotated the tires so am sure its from the rear was getting a vibration at around 55 or 60 from the front end so was mainly going in for a rebalance and figured id rotate them while at it .

 

The spindle bolt connecting the control arm to the bottom of the hub has an eccentric flange which I'm pretty sure is used to adjust toe-in.

I realized today while reinstalling rear spindle that this bolt also adjusts camber of the wheel. Not sure which way to adjust. The mechanics of the flanged eccentric bolt are simple enough I just don't know what it needs. Positive, neutral, negative camber?
It must have been adjusted near perfect because the tires have worn evenly.
Anybody have specs for this adjustment? Thanks!!!



1999 XK8 Cabriolet Alpine Pearl. (Gwendolyn)

 

The half shaft shims are for camber the spindle flange is for toe. Keep it simple. It's probably too late now, but if your tires were wearing true you could have marked the original flange orientation, returned to that mark, and been done. Hang in there.

 

You can turn this bolt and see both toe in and camber change. Minutely granted. If you need to do this with the cars weight on the ground thats honing to be tuf for me. I'll try string and straight edge and shoot for a little toe in for now.
Get it to a Alignment shop before installing new tires.
Another, very good thread I followed to help clarify points about removing rear strut assembly and replacing upper and lower bushes was very helpful but had no mention of this adjustment. Once I did notice it it was too late.




1999 XK8 Cabriolet Alpine Peal (Gwendolyn)

 

The Lower Pivot Pin Eccentric Adjustment only affects the REAR of the Pivot Pin. This is the Toe In adjustment

This (Toe In) adjustment will also change the Camber by a Very Small amount.

The Camber adjustment is accomplished by changing the Shim Thickness between the Axle Half Shaft Flange and the Differential Flange.

 

I shouldn't need to worry about the camber it was fine pryor to new strut bushes. I found a local alignment shop with a Hunter. They will be glad to check and adjust the rear toe.
I wish I had looked this thread over first. A quick mark on the bolt and I would have had it. I was just excited to find and fix rear bushes by myself. I hope the annoying clunking is gone.


1999 XK8 Cabriolet Alpine Pearl. (Gwendolyn)