While generally inspecting my front suspension (preparing for an alignment), I discovered "random" shims installed on the upper arms. Some Jag shims, some miscellaneous. I figure the last guy lost some of the originals, so I ordered all new shims from Gaudin. My shop uses Mitchell service information, and upon reading up on the alignment section, it clearly shows how the shims are to be positioned to begin with. On the right front, they show one thin shim in front, and two thicks and a thin at the rear. On the left side, they specify just the opposite; two thick and a thin in front, and one thin shim at the rear. Is this an error?? Seems like the caster would be way off with this arrangement. I would expect the same shim grouping on both sides to begin with. I know Mitchell simply collects their info from the various manufacturers. Anyone have an answer? BTW, I did purchase and install the lower arm eccentric bolts for camber adjustment. My 2004 still had straight cut bolts. One last question: My right rear camber is off slightly. I have a 4mm spacer in there now. Approximately how much in degrees does .5 mm on a spacer change the rear camber setting? Thanks ahead of time!

 

The shim order is not exact on each side. The spec actually has the passenger side slightly ahead of the driver in caster, to account for road cross slope.

Can you post up the shim schematic? My dealer said mine doesn't match either, but wouldn't tell me what it should be (they don't adjust caster in an alignment)

 

I will have to retrieve the Mitchell schematic for you. Look for it here tomorrow if I can figure out how to post it!

 

I took a photo of the Mitchell schematic and shim location recommendations, but cannot figure out how to post the image here. I have decided to leave them just as it says, and drive the car a bit to see if it pulls one way or another. The caster specs are different from one side to the other. So, it kind of makes sense.

 

Upper Wishbone shims are selected during manufacture to setup the caster. It's not a matter of exactly the same shim combination being used on every vehicle as they are used for final adjustment to even out manufacturing tolerances. There will be a combination of thick and thin shims. No reason to expect the same combination on LH / RH sides or leading and trailing side of each bush.

When changing the bushes, it's important to replace the shims in the the same positions.

Graham

 

Now you tell me. and who knew there were so many! Mine fell all over the garage floor when I pulled the bolt free. I was quiet for awhile...mumbling 'serenity now, serenity now'.

 

Anyone dare to claim they didn't do the same first time changing upper bushes!

Putting them back is an even greater challenge.

I keep an old Fulcrum Bolt with two inches cut off to help assembly. With the new Bushes fitted to the Wishbone, the Fulcrum Bolt is pushed into the Bush until it protrudes sufficiently to put the shims onto it. Coppaslip AntiSeize helps hold them in place. The old cut off dummy Fulcrum Bolt is pushed though the other bush and the shims put on in the same way.

The Wishbone can then be located on the Cross Member without dropping the shims.



As the Fulcrum Bolt is then slid into position, it goes through the shims and pushes the dummy Bolt out.

Graham

 

I understand that this arrangement I was speaking of was a "starting" point for an alignment. 2 red and 2 blue shims total at each side. I simply felt it odd that the initial setup recommended on Mitchell Service Information would be different from side to side. A logical person would think you would keep the sides near equal. I decided to try their basic setup, since the alignment specs given actually showed the caster specs different fron side to side. The car drives very straight, and the steering returns well, even before getting it aligned. BTW, the reason "I" am going through this instead of my alignment shop is that my guy is semi-retired, and just doesn't want to do any of the shim changing, etc! (It's pretty easy, but he wants nothing to do with it!) So he tells me what he wants, I set it up, and he checks it. Pretty crazy, but he's trustworthy!

 

It'll add greatly to the general knowledge on this issue if you can post the alignment difference specific thick/thin shim addition/removal makes.

Graham

 

chopr, you should be able to 'attach' a .jpg or other image file directly with your post. Try the GO ADVANCED button to find that option. I would very much like to see the 'starting' arrangement you found.

 

Ok. I am trying the advanced menu as suggested. I can see how to upload the image from there. Let's try it...

 

It came through! Sorry about the quality. I took a photo of the document with the second page simply folded and laid on top of the first page. Then tried to adjust the contrast etc. Hey, I am just a simple mechanic. Not a graphics designer!

 

Good info.
I've put some more contrast in your pic.



Graham

 

Hi,

very useful info, but I think there is a mistake:
it says that the thick shim will change the castor by 0.04 deg. This doesn't make sense:
a) too small value to be useful
b) SMALLER THAN THE THIN SHIM !!!
I think this is a typo and it should be 0.4 deg

 

Choir,
I did the same thing and dropped all my caster shims when I replaced my top bushings, and not knowing any better divided up the shims equally and reinstalled them with the new bushings.

When test driving after completing the re bushing of the front suspension the car tracked poorly, was not stable on the straight ahead, would follow any deviation in the road and in short felt very unstable. I realized the caster angle was the problem and a little research uncovered the diagram shown above by GGG.

To all intents and purposes there is no real down side to a high caster angle in vehicle with power steering, all it will do make it more stable in the straight ahead position. I decided to maximize the caster angle, I disassembled the top arm, and rearranged the shims placing them so I had the maximum caster angle. Now when I test drove it the car was very stable, tracked straight ahead, and did not follow any deviations in the road, and as time went on I found it was more relaxing to drive over long distances because it was so stable.

Never the less I had the whole front end realigned because of all the work I'd done in that area. When I reviewed the results I was surprised to find the caster angle was still not at the maximum allowable.

All the above is by way of an explanation because I don't think using the shims alone, you can exceed the allowable caster angle.
Regards,
White Bear.

 

Great info...due to the fulcrum bolt being seized, I had a couple washers rubbed in half. This info helps GREATLY! Anyone have an idea on torque of the fulcrum bolt?

Neil

 

From memory ~ 98 to 120Nm, I normally set mine to 110Nm.

 

Does the order of the shims differ with left hand drive vehicles to right hand drive ones?

 

Yes. The order is swapped across sides. The default starting point for the 8 shims on RHD cars, is:

RHS/driver's side - front: 2 thick and 1 thin. Rear: 1 thin
LHS/passenger side - front: 1 thin. Rear: 2 thick and 1 thin

Compensates for opposite road camber, apparently, but they don't allow much adjustment.

HTH,
Mike

 

I set both sides for max caster, eyeballed the toe and lowered the car with H&R springs and have gone 8,000 miles on a mixed set of used, barely in spec tread tires and the car tracks straight with no unusual tire wear.

The caster adjustment provided by the shims is so small I wouldn't worry too much about it. Not too many people in the US are driving their X100's on crowned country 2 lanes.