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I need to adjust the camber on the rear wheels of my '03 XK8 due to tire wear on the inboard edges. Looking at the suspension geometry, the road force on the bottom of the wheels causes the wheels to try to pivot about the lower wishbone pivot pins, which would make the tops of the wheels lean inboard (towards negative camber). The suspension links resisting that movement are the compression loaded half-shaft assemblies. As the universal joints wear, the half-shaft assemblies effectively become shorter due to the increased play. That causes the rear wheel camber to become slightly more negative. If I hold the wheels at the 9 o'clock and 3 o'clock positions and try to rock them, there is no perceptible movement. If I hold them at the 12 o'clock and 6 o'clock positions, I can rock them with about .030" play at the edges of the rims, measured with a dial indicator. Does anyone know what the maximum allowable play in u-joints is?
I'll probably replace all four u-joints for good measure and take the car back to the alignment shop. Then, the issue will be the availability of the correct thickness shims. Camber is adjusted by using spacers/shims of various thicknesses between the differential flanges and inboard u-joint carriers. Jag provides those in a just a few thicknesses (outrageously priced). I'm thinking about making .020” thick stainless steel shims the same shape as those OEM spacers that I can stack on top of the existing spacers to more accurately "dial in" the camber angle. Just wonder if anyone has tried something like this?
There is supposed to be rear wheel play in the 12 o'clock and 6 o'clock movement. Off hand, I don't know what the actual measurement is supposed to be. The .030 you posted doesn't sound abnormal because that play you measured is actually coming from the wheel bearings inside the knuckle assembly. Unless there was rust dust coming out of the U-joints or abnormal movement, don't go replacing them. I have never replaced any in all the Jags I've worked on. There are 3 ways to adjust rear camber.
1) Shim between the differential flange and inboard u-joint carrier (as you stated).
2) There are different thickness shims that go between the 2 wheel bearings inside the rear knuckles that adjust that play you measured and in turn it will adjust camber.
3) The bolt that connects that lower wishbone to knuckle at the bottom is eccentric which means the camber is adjustable. I believe it actually adjusts both camber and toe within that one bolt.
I vouch for option #3 and save yourself a lot of work.
Hmmm, I didn't know that... Maybe the earlier X100's had the eccentric and the later ones didn't?? I know both of our X308's have an eccentric bolt. It's pretty much the same rear suspension setup between the two models. Well, that is until you told me that yours doesn't have an eccentric RJ.
Whilst lowering the '05 XK8, I visited this site for clear info. Lowering the car requires adjustment to the rear camber. Thanks to a fellow for posting the correct way to bring the rear clamber back to 'specs'. Posted below is the link to the tread which set me on the road to get it right.
Jagbits is the way to go. On their site, the axles shims and the rear axle 'spacers' are in two different sections of the site, so a call might help in finding the two parts.
''3) The bolt that connects that lower wishbone to knuckle at the bottom is eccentric which means the camber is adjustable. I believe it actually adjusts both camber and toe within that one bolt.''
It should be. When you take this apart to change springs/shocks and/or lube the pivot bearings, you need to mark the bolt location or you will screw up the rear alignment.
RJ, it more like the head flange on the bolt is eccentric rather than the bolt itself. The flange is off center and it fits between 2 raised edges on the hub. As the bolt is turned the off center flange moves one side of the hub in/out. Don't worry too much if you turn it without marking, just set it half way and it won't be too far out.
Some interesting replies and comments from my fellow X100 owners. Thanks for your input. My car does have the eccentric flange head bolts installed. See the photo. They are intended for adjusting toe-in (rotating them does affect the camber angle slightly). Regarding the wheel bearing question, if those tapered roller bearings are worn, I believe you would feel play when rocking the wheel anywhere around the circumference - not just when holding at the 12 o'clock / 6 o'clock points. That's the case with my car. I only have play about the 12 o'clock/6 o'clock plane and I can see very slight axial movement at the u-joints. I got started down this road after taking the car to a local Jag dealer to have an alignment done after fitting new tires. They wanted to charge me $1900 to change my rear wheel bearings. They couldn't explain the lack of play or noise when I challenged them. Their alignment machine indicated that three wheels were out of alignment while the fourth, the one with the tire that had actually worn down on the inboard edge, was within spec. Again, they couldn't explain how that could be. At that point, I had them take the car off the lift, I paid them for the alignment that they hadn't done, and I left - never to return.
I know you're not lowering your car, but lowering mine creates the negative camber that you are witnessing through worn parts on your car. My local automotive shop lowered the car, resulting in rear negative camber. With proper shims in hand, the local hop-up shop installed the rear shims I purchased from Jagbits. Installation time was 45 minutes, or $75.00. The local Les Schwab did the 4 wheel alignment. While looking at their charts and graphs I asked what 'thrust' is. That is the final adjustment so all four wheels are pointing in the same direction so the car goes straight. This 3 stage project was all planned out and agreed to by the 3 shops.
Because the Jaguar dealer is 80 miles away I don't need to deal with them. And because I've almost never taken a car, boat ,motorcycle to a dealer it is the local shops I deal with and have found all of them to be more competent then dealers. Dealers sell cars and do warranty work. I hope this helps you or other members.
Hello Jip,
Thanks for your comments. I agree, a competent independent shop is the way to go.
To more accurately "dial in" the rear wheel camber on my car, I plan to machine thinner shims from .020" or .030" stainless steel shim stock that I can stack on top of the existing thick spacer and get the camber angle just right. All I need to find now is a used spacer that I can use as a template to lay out the shape of the shims from. If anyone reading this post happens to have one lying around, I'd appreciate hearing from you.
The camber adjusting shims from Jaguar are available from 3.5mm to 7.5mm.
MOST of the cars I have aligned when I worked at the dealer are set from the factory with 4mm shims.
Most of the cars need 6mm shims after years of 'settling'.
Playing around with raising or lowering the car will need 'experimentation' to get the desired camber.
The camber setting is a RANGE so I don't think you need shims that thin (20 to 30 thou) but you can get it closer that way.
The recommendation is to use ONE shim as opposed to stacking them. Many opinions on the 'bad idea' of stacking them.
Thanks motorcarman. I appreciate that info coming from your professional experience. So, is a 6mm shim pretty typical to correct the camber in an older XK8? I've read opinions about using one shim rather than stacking. From a purely mechanical perspective, I don't understand the reasoning. In fact, am I not correct in thinking that earlier XJ6's stacked thin shims to adjust camber?
I've read opinions about using one shim rather than stacking. From a purely mechanical perspective, I don't understand the reasoning.
One forum member indicated that both of the Flanges (Differential and Half shaft) have a protrusion that centers the Flange in the Center of the Shim. Without this, the clearance in the Bolt Holes could cause a out-of-balance condition. However, some members have stacked the shims without a problem.
Most of the cars need 6mm shims after years of 'settling'.
bob
I keep the 6mm shims in stock for customers to take to the alignment shop if they want to get the rear camber adjusted.
I keep ONLY the 6mm so if someone needs another size, they will need to order them.
The shims are kinda pricey at about $40 each so I don't keep the full inventory.
If the camber is slightly negative with the factory 4mm then the 6mm should get you in the GREEN zone on the alignment.
If the camber is too far out then I would investigate the cause. Maybe a faulty diff output bearing or damaged hub bearing???
To be on the safe side, I ordered two 3.5 mm shims and 12 0.46 mm shims (these things are only available in 7.5 mm, 3.5 mm, and 0.46 mm thicknesses). The 3.5 mm shim was $39, while the 0.46 mm shims were $1.00 each (that’s why I didn’t mind getting a few extra). Please note: I could not find anywhere that said the 0.46 mm shims would even work on an XK8. Because both the 3.5 mm and the 0.46 mm were listing as working on a late XJS, I thought I would give it a shot.
Well, after some trial and error (installing both 3.5 mm shims and adding / removing the 0.46 mm shims as needed) the rear camber measurement is -0.6 degrees left and -0.3 degrees right. When viewed from the rear, the car looks as it should with the wheels / tires filling out the wheel wells nicely.
Below are the parts numbers and vendors for the shims. Jagbits had the best pictures and descriptions, Jaguar Parts Cheap had better prices (you have to search using the part numbers).
Part #: C16621 .46 MM Shim
Part #: CBC480635 3.5 MM Shim
Part #: CBC480675 7.5 MM Shim
Jip here. You won't need the expensive $39.00 3.5mm spacer, just the outlandish $1.00 shims at Jagbits. Come-on, you've got a buck or 6.
The correct shims are in the XJS or XJ6 page. I called Jagbits as to why the XK shims are only on the XJ page and not the XK page. He said an outside company set up their web page and goofed, slightly. They'll correct that, someday.
This would be the shim you'll need.
12-17-2016, 06:59 PM
XK8 Rear Wheel Camber & U-Joints
