I have a 1996 XJS Convertible with the AJ16 engine.

I just recently replaced both ball joints, the upper control arm bushings and the outer tie rods on both sides of the front of the car.

I took it in for an alignment and the camber is off.

The reason I replaced all that rubber, is because I had an awful wear pattern on the front drivers side tire. I would get a 2" strip on the outer edge of the tire that would be BALD way before the rest of the tire.

I thought that I needed to reduce the camber on that tire, so when I was replacing everything, I added an 1/8" shim to the two bolts on that side only. That was on top of the 1/4" of shim already there.

Once completed, I bought a new set of tires and sent it in for a 4 wheel alignment. Well the camber is off.

The front passengers side (with the original 1/4" of shims) is at -1.4 degrees.

The front drivers side, where I increased the shim stack to 3/8", is at -2.7 degrees.

I don't know what I started off at.

I looked in the book, and it says that 1/16 of shim will adjust camber by 1/4 degree.

It doesn't look like I have enough shims to pull out to get to the -0.9 to -0.1 recommended range for the drivers side. It also would appear that my car would not require any shims at all.

Is there anything else here that would adjust what the garage was reading as the camber?

Also, if I pull these shims, would I require another alignment? (I realize I would like to put it back on the rack to get another reading, but by playing around with these shims only, am I screwing up caster or toe?

Thanks.

 

If you adjust one field, the rest move also, so YES, a new "rack" as you say will be required.

Not real sure on the update set up, but on my earlier ones getting the camber/caster correct was a juggle, mostly coz they did not understand the caster shims at the balljoint, and the need to maintain the same thickness shims to the 2 camber bolts.

All of mine have a single "medium" shim on each top pivot bolt.

Bent sub-frames were an issue on some earlier cars, but never heard of an update having that issue.

 

If you do not completely understand what will shift during an adjustment, then you should not be attempting to do a wheel alignment. There is no need to get it in the ballpark before work commences.

Once a car is at a qualified alignment shop, then it does not come off the rack until the alignment is in spec, or there is a known reason that it is impossible to get into spec.

There should be no need to be aligning twice on the same job.

 

The reason I ask is because I did have my shop do the alignment, but they did not adjust the camber because they wanted to charge more labor hours for that.

They did not know that (according to the manual) 1/16" shim equals 1/4 degrees.

I wish they did tell me that playing around with the shims was an option because I would have paid them for the work.

 

Vee
As per my contribution to your last thread, the camber should be:
between 1/4° to 3/4° positive (ie top of wheel slightly tipping outwards). You have below indicated that some negative camber is correct for your model (later edit by greg))

Assuming this is correct for your vehicle you now indicate that your camber passenger side "is at -1.4 degrees. The front drivers side, where I increased the shim stack to 3/8", is at -2.7 degrees".

If you really mean "-" = negative camber, then they are both wrong. Either way, it can be corrected. If DO you have negative camber (ie top of wheel slightly tipping inwards) then shims need subtracting from between the fulcrum and the subframe to tip the top of the wheel further outwards.

If you in fact have negative camber on both sides then the one that badly needs fixing is the one with 2.7° of positive camber. To get this down to 1.25° is a difference of 1.45°. You have 3/8 = 6/16ths of shims in it, so 6 x 0.25 of a degree gives you 1.5° of adjustment. So it can be adjusted back to spec. The other obviously has enough adjustment shimming to pull it back within spec.

FWIW, I would always have a camber and toe recheck after doing the changes. Also, get them to check the castor, as I mentioned previously. Any bending of the subframe (unlikely as Grant said) could well show up in that.

Greg

 

Greginfrance,

Thank you for your continued interest in my problems.

The garage, as well as my Jag Manual shows that camber should be negative 1/2 degree +\- 1/4 degree. (the garage actually shows the spread to be +\- 1/2 degree)

I went I there and I found that I had a shim stack of 11.6mm or 0.45" on the wheel that had a camber of -2.7 degrees. I removed all of them. That should get me to about -0.9 degrees.

On the passengers side, where I was at -1.4 degrees, I had a 6mm shim stack (or 0.25"). I took half of that out, so I expect the result to be at -0.8 degrees.

I'm going to go back to the garage since I thought it was very easy to get to the shim stacks. All I mid was support the assembly using a jack at the base of the lower ball joint. I then undid the two bolts holding the upper fulcrum shaft in place and then I pulled out the shims. Took me longer to get the car up on jack stands than it did to get to the shims...

 

Vee
I think my explanation of the system in my last post was wrong (as the fulcrum is inboard of the subframe, I was thinking it was outboard) please accept my apologies. To reduce negative camber means reducing shims, I have edited my last post.

At this point you seem to be up against it, as 0.5° of negative camber seems unobtainable. Accurate measuring of the distance between the subframe towers, maybe? looking a bit like a subframe problem I must say.

MAybe get the camber as close as possible ans see how the tyres wear? A bit more negative camber than spec will not in itself ruin anything.

Greg

 

I believe if I can get both front wheel close to -0.8 degrees, I'll be fine. It won't be the perfect -0.5 degrees, but I do believe it'll be close enough.

I took the car back into the shop. They did tell me that adjusting camber is not included in the price of a typical alignment. After I asked whether it would have been cheaper than a second alignment, I was told not to worry about it and that they would take care of it.

I hope that is what I think it means...

I did explain how simple getting to those shims really was. I think they thought that the control arms would have to be removed. Not at all, just make sure theres something supporting the lower ball joint and it's pretty simple.

I'll post back the results. I am really curious to see if the math works out that 1.6mm = 1/16" = 0.25 degree

 

Well the math kind of worked.

I was absolutely correct on the driver's side. I started off with a camber of -2.7 degrees. I ended up with -0.8 degrees. That's with the entire shim stack removed, so it looks like that's the best I can do. The PO must have had an accident at that side...

The passenger's side is strange. I started off with -1.3. I ended up with -0.4 degrees. There must be something wrong with that wheel because unlike the driver's side, the value fluctuates. On the original sheet the driver's side never changes. The passenger's side shows -1.4 then -1.3 degrees. I chalked that up to a rounding error. Don't know how I botched the math there. I was .33 to .50 degrees off. I should have inserted a 1/16" shim back in there. Oh well.

On the new sheet it starts at -0.6 then ends up at -0.4 degrees. In both cases the shop never attempted to adjust the camber shims.

My caster was at +4.0 and +3.6 degrees. (drivers/passengers) Now it's at +4.5 and +3.8. The mechanic never adjusted the caster after I made my changes to the camber shims, since they are unchanged on the new sheet.

He did adjust toe. The old sheet started out of spec at +0.33 and +0.37 then fixed to +0.19 & +0.20. The new sheet started it at +0.18 and +0.28. The mechanic adjusted them to be equal at +0.16 on both sides.

Last issue. The rear toe is set at -0.13 and +0.11, both within spec, but it's odd that one is a positive and the other a negative, I would have hoped to get them close to zero, or at least one on the positive and the other on the negative?

Thanks for all the help.

 

If one wheel is negative and the other is positive, perhaps the IRS is cocked to side.

 

Well, it is in within tolerance, which is between +0.17 and -0.17

 

Belt it around for 2000 miles and let us know what happens!

As for:
"The passenger's side is strange. I started off with -1.3. I ended up with -0.4 degrees. There must be something wrong with that wheel because unlike the driver's side, the value fluctuates. On the original sheet the driver's side never changes. The passenger's side shows -1.4 then -1.3 degrees. I chalked that up to a rounding error. Don't know how I botched the math there. I was .33 to .50 degrees off. I should have inserted a 1/16" shim back in there. Oh well."

I think that a 'fluctuation' of 0.1° is well within the tolerance of the rim roundness! But if you have a spare few hours putting a shim back in would not do any harm. Good Luck

greg

 

If the outer edge of the tire was wearing that would indicate positive camber. Sounds like you have got it under control.

In my day job I have to diagnose complaints of pulling, etc. Most times when an alignment can't be adjusted to the specs or things don't make sense it is the alignment rack. Ask when it was calibrated last. Is it truly level? Are the turn plates in good working condition and not rusted, etc. Many new car dealerships I go to do not keep their machines in good condition. I can only speculate as to the independent shop.