Shims inside the tophat - front wishbone fulcrum
 

Hi All,

Need some reassurance/ education. I've read through the shims posts but haven't seen anything that answers my questions.

Recently swapped out most of the front suspension on my 99 xk8. New lower wishbones, dampers and springs. To get the dampers in the top fulcrum needs to come out.

Having just put the car back together I realised I may have made a mistake on one top wishbone when reinserting shims. On the first one I actually put the shims inside the top hat washer on the bush. (Was hard to see how they came out as they fell to floor). Am I going to cause damage with them being inside the top hat washer against the bush? I'm reluctant to pull it all out again so soon but will if this will cause damage.

The second wishbone was easier to manage and I saw the shims were outside of the top hat and kept them there.

Thanks for any help.

I think the bush will most likely not function as intended with caster shims where you now have them. The bush is actually more of a free turning bearing than other suspension bush designs and those shims will likely now restrict the free rotation of the component parts.

^^ +1
I can't remember exactly how deep the dish is on those washers, but not having the shims between the the inside one and the crossbeam means that it will crush the inner to some extent against the crossbeam.

It's important that everything between the pivot bolt head and its nut is clamped properly, so that nothing in there can rotate (think oval holes in the crossbeam).
The caster will also be wrong - although not by much as there's very little adjustment.

I know it's a bit of a fiddle, but I'd re-do that side.

Thanks both - I guess she's going back up in the air..

Think I have bigger problems though, there is a weird hollow knocking coming from somewhere and its noticeable through the steering wheel. Hope the top wishbone resolves it but fear there may be more to do!

Took it to a local garage to get it put in the air properly and all installed components are tight and right. Guess it may be the top wishbone bushes as this is the only part not replaced :'D

Just a thought:- did you tighten and torque the lower wishbone bushing bolts with the car on the ground?

On the knocking.
Check that you have 5 threads showing on the top shock shaft nut area.
There are a lot of new mounts out there with the hole in the internal washer that is too small for the shaft of the shock to let it go all the way down to the shelf as designed.
If you have less than 5 threads the mount is riding on the rounded area of the shaft and will knock badly and go off center in a few miles.
Solution, take it apart again (unfortunately) and ream the hole in the washer to 12MM, if you get it done quickly, it will save buying new mounts again.

^^ As Wayne said above, it is very important that you crank that top shock shaft nut down tightly. You want to see at least 5 stud threads showing above the top of the nut....

Thanks for all the suggestions - I believe the dampers were a snug fit so no issues there but plot twist... During testing they completely refused to compress under any load.. both sides. So when load was applied to the lower wishbone the whole chassis just lifted in unison. Once I took the dampers back out all the other components moved without issue under load.

Very strange as tested the dampers before they were loaded. I can only assume the springs are causing the issue.

Have now taken the dampers out and will take them to the garage to be deconstructed and tested tomorrow.

Good news is the top wishbone fulcrums had to come out both sides so will.be able to amend that mistake 😁

It wasn't a mistake you were just looking for a better way to do it. lol

Now all back in the right place. Turned out the garage that assembled my damper assemblies overtightened the top nut. Cost me another damper but once replaced all worked fine. Had the dampers in and out 3 times of the weekend, testing the old ones for comparison. Once you've danced with the shims a few times it's not as frustrating.

As an advisory to others the top nut looked tight and the top mount compressed correctly. The only tell was a horrific knocking noise coming from what seemed to be the dash but was actually the mount in the wheel arch because the nut had shredded the threads and was indeed loose. First diagnosis was that the new suspension was firmer and had shaken something loose but a Jag specialist picked it up when he tried to tighten the top nut on the car and it just span. An extra nut on top was a great temporary fix but ultimately a replacement damper was needed so just went ahead and did it.

Next onto the rears...