Odd mysterious shim on one side only on front wishbone ???

[Orkney]

Bit of an odd thing ....
Last couple of days been spending a coupe of hours at a time replacing teh bushes on teh front passenger side along with good old clean up and paint.
Anyway was re assembling yesterday ready to line up and bolt up today when yet another mechanical anomaly occurred.
There was a shim on the passenger side that wasnt on the drivers side.

Its a rectangular metal plate about 1/2" thick, rectangular 1" x 5/8" with a hole in the middle.

It was located (this is how it came off) between the wishbone fork & front wishbone arm.
Thought it really odd and why was it there as was just a plain washer on the other side.
have measured both wishbone tie bars, they are identical, but either the wishbone fork or wishbone arm (front) must differ in some way. Dry fitting without this shim there is just room to get the bolt through the fork, but insufficient to turn it or spin a nut on.

The wishbone forks seem to measure the same from the front inside face of the arm to hole centre - so whats going on?
Going to measure the arms in a while to see if ones longer in cross section or somesuch.
Just seems really odd as to why this shim was there - reluctant to put it back on, would rather grind a small radius from the arm to allow the nut and bolt to be tightened than put the shim back and know that the front alignment is out by 1/4" at the wheel centre.

Any ideas anyone ?

[bmcecosse]

There was a long thread about this just a couple of weeks ago. It should be there as standard. Best to make both sides the SAME - either both thick shim or both just washer. The thinner the shim (or washer) then the more caster angle on the front suspension - which will make the steering a little heavier but will give better turn-in (tends to increase negative camber on lock). Look at any modern car sitting on full lock - the outside wheel has pronounced negative camber. However - i'm not sure if this will be important to you on Orkney!

[Orkney]

Ah cheers that makes sense !
Couldn't see hide nor hare of such a shim on any of the manual diagrams, but the one had certainly been there a long time as there was an impression in it from the back of the fork.
The side which never had one was just a bog standard washer, did away with the shim on the other side and a similar washer was just enough to get the bolt through and the nut on.
Noticed something else whilst just refitting the wheel on the 'was shimmed side' which was that the inside of that tyre is completely worn. Wonder if its related?
Going to have to pop it in for tracking anyway next week as the replacement track rod ends were 3mm longer - consequently had to move the locking nut back 3mm either side jut to approximately get them on.

Just gave it a test run and all is very well indeed, the new bushes make it feel like driving a different car

[rayofleamington]

The packing piece should really be there on both sides.
Removing it will ncrease the pre-load from the tie bar and pull the wheel forward a bit with more stresses on the lower arm than normal.

With disk brakes and wider wheels it the tie bar setting can be far from optimum as more load = more movement. Different bushes can be used but if you want perfection, a neater way is to get adjustable tie bars and have the suspension geometry set up proffessionally (not that essenial for tootling down to the shops!!)
The front end alignment can be out of kilter due to accident, rot, bad repairs etc... so on some cars the effect of the tie bar spacer plate can be pretty minimal compared to other geometry issues.

Re-tracking will be pretty much essential if you are getting uneven tyre wear - Minor front tyres will wear very evenly if the tracking is correct/standard (unless the car itself is out of alignment!)