Jag front suspension Caster Shims

[rover]

Folks
spent the last hour going through past posts regarding Caster shims and can't find one that gives me the answer. So can anyone help ?
The top susp arms had 8 shims altogether 3 to the front and 5 to the rear of the top ball joint. For a GD what is the best starting point ? or best setting ?
I have attached pictures of one of the shims, both top and bottom arms if needed.

Many thanks

Mark

[Miket]

Mark

8 Castor shims I had 4 on mine, all depends what thickness they are.

Why ask here, I would have thought it would be best to contact GD for the correct castor settings and adjust the ones you have to suit.

[midlifecrisis]

I had 4 on each side - 3 on the front and one on the rear.

[wilf]

Each car will need to be set up individually, there really isn't a "correct" number of shims. Sorry.

A castor and camber guage looms near in your life!

[Purple AK]

Best check with GD on this one. As there are two or three types of top wishbone, with differing degrees of angle front and rear. The ones in your Pic2 dont appear to be a true pair, as only one should have the champered top to the old bumpstop mounting point.

[Grease Monkey]

Have to agree, 8 sounds high! I thought they normally have either 3 or 4 per side depending on the mark of the original donor.

Also the upper wishbones are usually asymetric with the arm with the cutoff lug to the front.
I'm currently running all 4 shims to the front to give maximum self centreing for the SVA. I think i need to move one to the back to reduce the effect somewhat.

(Looking at your lower arm, you may be running a slightly different setup. Does the arm for the ball joint angle forward slightly, as it doesn't look like it)

[rover]

Guys
thanks for your replies, when you are talking about 3 or 4 shims what thickness are they mine are 40 thou each.

Chris
the top arms are chamfered towards one of the bump stop mounts so I think they must be a pair.

Adrian
I have taken another pic of the bottom arm is this the same as yours ? Would your shims be about 40 thou or thicker

Thanks

Mark

[Grease Monkey]

Nice picture, wrong angle. My lower wishbones, when viewed directly from above, have the ball joint arm angled forwards. Then with the upper wishbone, with unequal length arms fitted with the chamfered knob forward, i need 3 shims at the front.

I think all 4 shims together come to around 5mm or so. (What is 'thou' thing you speak of old timer! )

Update... 40 thou = 1.02mm, so that sounds about right for 4 shims..

[Miket]

Rover

Once the top arms are tightened up on the shaft, the gap between the ball joint and the arms should be pretty well determined, it will them depend where you require the shims to get the correct castor. ie infront, behind or 2 each side of the ball joint.

If the gap is to large for 4 shims, then you will have to put more in as you don't want to tighten the arms and put strain into them.

Looking at the picture, the gap looks about right for 4 shims.

[callum]

The number of shims is going to be determined by the length of the inner pivot bar, the bushes and the angle of the arms themselves. The latter come in 2 types - straight and cranked. I think the cranked type take 4 shims and the straight ones 8. You seem to have cranked arms and more shims than you need. Whatever - you do not want to induce a pinch in the bushes, just to triangulate the arms with the upper bj mount snugged up. The lower wishbone should be in the right place (neck forwards) relative to the upper wishbone assembly as this is fixed by the GD chassis. I would be surprised if you need more than 4 shims total but if you keep the forward bias as near to 3:1 as you can manage you should be in the right ball (sic) park. It is also easy to adjust anyway.