2003 XJ8 sport with 125k. I just changed the upper shock bushings that was crumbling, and then I was going to change the lower sway bar bushing and saw that the inner tire on both sides worn bad. What caused it? The outer tire is about 80% left. I'm thinking it's the shocks. The upper cushion bumper bushing that is cover by the boot was also worn out and crumbling. Is it bad SHOCKS? BTW the shocks color is green so I'm assuming it's the original. Lower arm bushing and lower ball joint are pretty good, not worn. Thanks.

 

This is often caused by a combination of improper alignment settings, such as excessive toe and caster. One-sided shoulder tire wear: This type of irregular tread wear means the inside or outside shoulder rib of the tread is significantly more worn than the other ribs.

 

+1, it is mainly the toe-in on these cars.
There has been a good thread on this by a very experienced guy called Brutal, you might want to find it, long time ago.
Basically it came to the point that during the toe-in setting, you should use a spreader bar on the fronts (pushing it put by hand is possible too) while setting the toe-in.

Mine were worn to the thread, but the new tires seem to hold well after a proper alignment and setting the toe as per above.

 

Most likely alignment. As time goes front suspension bearing, bushings, ball-joints - they all give a little causing wheels to 'fall in' and chew tires on the inside. So when aligning people like to over-correct it. When I had the same problem - I had to replace wheel bearing because it was 'used up' and shop could not align suspension anymore...
Shocks really don't have much to do with it.

 

Agreed on bushings and ball joints going bad. If your wheel bearing was shot enough to affect alignment, I'd imagine you could take the wheel and wobble it decently far by hand when the car was up in the air, correct?

Shocks don't affect alignment in the front. If you were to take the shocks out in front, the car would rest at the exact height it would rest with the shocks in. In the rear however, struts are used, so the shock is an integral part of the suspension. Things like lower shock bushing and the upper mounting bushings can cause the rear to sag, affecting geometery and therefore aligntment. I'm actually dealing with this now, looked the rear subframe over and saw that the big upper strut bushings are all cracked and rotting.

The easiest, but not comprehensive test, to check the suspension is to get wheels in the air and try to move them by hand, checking for play while doing so. Obviously keep in mind the steering moving when checking front wheels... next it to take the wheels off, visual inspection of consumable bushings, and prybaring things to see what moves in ways it shouldn't.

 

Update...I got 2 fresh front tires today and was ready for an alignment, WELL...
The alignment folks told me not to do it because it had a bad negative camber caused by bad shocks. What!!!!???? He said he can do it but I would be wasting my money because it won't align properly until I change my shocks. My ball joints looks ok, but I have to check the wheel bearing. Guess I have to take one step at a time.

 

ok, what shocks did you put? Green shocks were for the R Sport Suspension. I believe the XJ8 Sport had those, idk. But what company shocks, those cheap Chinese shocks wont handle this heavy of a car.

 

I want to call that BS.
As Nilanium mentioned earlier, the suspension and shocks are separated on the front, and the shocks have little to non effect on the alignment.
It might be that due to worn items the camber can't be restored, but you can only find out by actually wrench a bit, and see results (did he give you a print of before and after?).
Still, camber, unless very far out of the lower tolerance, does not cause the inner wear, inappropriate toe-in does.

 

This thread is good to get an idea of all the consumables and bushings in the front suspension. https://www.jaguarforums.com/forum/x...-parts-163275/

I'll say it again, while bad shocks and mounts will affect ride quality and handling, the geometery of the car's front suspension is not affected by the state of the shock, unless it's stuck extended or something extreme like that.

Here's another picture, showing the front right suspension, as seen if standing at the front of the car looking towards the back. 2001XJ8FrontSuspensionDiagram1.jpg Photo by Jim0206 | Photobucket

 

That's what I was thinking also that the suspension and shocks are separated on the front. and you all confirmed from the posting. I was surprise when he told me I needed new shocks before the alignment and it caused the neg camber.

@ Omgimali- I haven't put any new shocks in yet. I think they are original. It's green sports suspension. I do have 03 Sport. Third owner, don't have the previous records. I'm going to install KYB.

 

You can check your ride height.
Although very unlikely, if your car sagged extensively, or the PO got a ring of the spring cut, then camber will increase.
Most likely worn parts, or an incompetent technician though.

 

I was re-reading original post... and it is not clear if we are talking about front or rear tires/suspension. I assumed front... from the rest of the discussion it sounds like we are talking about front. Right? (well, replacing upper shock bushings I guess can only be done on front)

I am still a bit iffy about how much rear shocks affect rear geometry, was always under impression that on our cars rear geometry is decided by shaft and lower arm. Granted, if car is notably sitting down - it has effect, but it is springs to blamed, not shocks.

Camber or toe - either one will do wonders to tires, it is just in my experience it is camber that usually goes bad(negative) over time on front tires of rear-wheel-drive cars. But of course both can go bad and that is why it is a good idea to check alignment often.

 

Front tires, if nothing else, there's no ball joints in the rear suspension. Unless you count those spherical lower strut mounts..

I'm not sure about the rear geometry, if the half shaft and the lower arm are the same length then wheels won't camber inwards much under lots of squish or ride height drop. I think they're pretty close. In the rear the behavior is different than the front since the shock and spring form a strut. So, the shock itself won't affect ride height, but since the shock and spring are a combined unit, a worn lower strut mount, or deteriorated upper coil spring isolator (the big foam donut), both being part of the shock/spring assembly, can decrease ride height. Bad/cut spring too of course.

 

the bilstein sport shocks for the x308 are the way to go