My rear tires besides being shot are both heavily worn on the inside of the tire. Both sides of the car have the same wear pattern. Does this indicate a rear wheel suspension or alignment problem, and what can be done about it?





Rear tire wear - same both sides of car

 

The Camber is excessive. The Camber can be corrected by increasing the Shim Thickness on the inboard end of the Half Shafts from the stock 4.0mm to 7.5mm.

Incorrect Toe-In (or Toe-out) can also cause a problem, but the Shim Change should fix the Problem.

 

Thanks Paul. From this note I was able to find other useful applicable posts including some from you. I guess my next step is getting under and measuring up the flanges to make the shims. We have a laser cutter and stainless steel sheet at work so we'll run a government job...

 

Keep in mind that the Shim should be a single item.

There are small Ridges on the Flanges that Center the Shim.

Stacking Shims would defeat this Centering feature.

 

could the camber issue be caused by worn shocks or tired/lowered springs?

 

The shocks pass the "bounce" test ok and the car at least sits level. It seems somewhat unsettled however when driving over a rough patch especially when pressing the gas pedal. I'm new to this car so I don't know if that's normal or not.

And Paul thanks for that tip so I need one thick shim instead, with dimensions suitable to locate on the ridges you mention.

 

More to this story- using a level I measured about .75" departure from vertical over the 18" rim height. By rotating the eccentric bolt at the bottom I can get this down to about .12" which equals .38 degrees (top inside of bottom). Is this a good fix? What is the camber target? Getting the half shaft off looks like a bear...

 

The lower eccentric bolt is for Toe-In adjustment NOT Camber. It will affect the Camber but the eccentric affects only one end of the bolt, hence Toe-In.

 

Incorrect toe-in will make things worse not better. So measure your
toe-in first. I run a "smidge" over zero for better wet stability. If your
toe is good with the lesser camber, then maybe all is well and it was
a case of the eccentric moving over time.

The halfshafts, by all accounts are not that difficult since you only need
to work with the inner end. The outer end stays attached to the hub.

There are also spring packers (shims) available to raise the rear a bit.
This would decrease negative camber a bit.

.75/18 suggests 2.40 degrees according to my spreadsheet.

How good is that mini-compressor? What tools are you able to run
satisfactorily with it?

 

Thanks Plums I ordered 2 shims from SNG-B. All they have in stock in USA is 6mm but I can measure them up and make others if needed. Then I'll take it to get 4-wheel aligned, managed to find a shop willing to tackle it.

That eccentric bolt wasn't very tight when I went to loosen it so maybe as you say it just worked its way around. It was about at the low point for camber.

That little compressor won't run anything, it's only good for filling tires (slowly) and blowing dirt off. My big compressor died and it was only $40 from Harbor Freight.

 

Ah, ok. I picked up a Nardi compressor about the same size
just because it is small enough to cart around and runs on 120VAC.

I would suggest measuring toe at your "revised" settings before
installing the shims. It might just be a question of playing with
the toe.

According to MotorcarMan, the 6mm shim fixes almost all problems
due to sag. If they are too thick, you probably have the equipment
to mill a bit off.

 

Reading another thread about ride height, it said to measure ride height from the center of the wheel to the bottom edge of the fender. Spec is 15.74 front, 15.94 rear (1998 XK). On my car I'm measuring 13.75 front, 15.00 rear. My front tires seem to be wearing evenly and the back are not. What the....?

 

Front might have correct camber since front is easily adjustable
without shims and is a routine adjustment.

Ride height in the rear can be adjusted with the spring packers
I mentioned earlier. Or new springs.