Griff Steering Geometry?

[TVR Dummy]

Has anyone got the set up for a pre-cat Griff? I'm sure I saw a .pdf on here before but can't search.

[g8ape]

Front track: 20 minutes toe in
Front camber: 1/2 degree to 1 degree negative (3/4 ideal).
Rear track: 20 minutes toe in
Rear camber 1/2 degree to 1 degree negative (3/4 ideal) the same as the front.

I set my 92 plate to the above settings after fitting new wishbones (one piece upper fronts) powerflex bushes, Nitron shocks, Eibach springs, upper and lower ball joints and track rod ends and it drives as I guess it would have when new (but a little firmer).

[Ab Shocks]

g8ape said:

Front track: 20 minutes toe in
Front camber: 1/2 degree to 1 degree negative (3/4 ideal).
Rear track: 20 minutes toe in
Rear camber 1/2 degree to 1 degree negative (3/4 ideal) the same as the front.

I set my 92 plate to the above settings after fitting new wishbones (one piece upper fronts) powerflex bushes, Nitron shocks, Eibach springs, upper and lower ball joints and track rod ends and it drives as I guess it would have when new (but a little firmer).

Thats the old settings for a road car
Revised settings from 2005
Front
Camber = 0.5 to 0.75 degrees neg
Toe = 12 minutes toe in overall
Rear Camber = 1.4 degrees neg
Rear Toe = 24 minutes toe in

[The AJP Griff]

How you like it set up is a very personal thing and tastes can differ a fair bit. I found starting with 1 degree negative camber all round and just the minimum of toe at front with 20 mins rear is a good starting point. I noticed no-one has mention caster either? Ive always found it more effective to make sure both sides are exactly even rather than going for an overall target figure as well,ie if you cant quite get what you want on one side then match the other side to it rather than go for a total figure like youre local tyre depot is often more concerned about.

[Ab Shocks]

The AJP Griff said:

How you like it set up is a very personal thing and tastes can differ a fair bit. I found starting with 1 degree negative camber all round and just the minimum of toe at front with 20 mins rear is a good starting point. I noticed no-one has mention caster either? Ive always found it more effective to make sure both sides are exactly even rather than going for an overall target figure as well,ie if you cant quite get what you want on one side then match the other side to it rather than go for a total figure like youre local tyre depot is often more concerned about.

Castor is fixed and unless you go to somebody with a Hunter machine and some different thicknesses of shims you will struggle

[The AJP Griff]

Ab Shocks said:

Castor is fixed and unless you go to somebody with a Hunter machine and some different thicknesses of shims you will struggle

But thats just it,castor isnt fixed and is adjustable,am I the only one bothering then?.I dont know what my garages machine is but its some fancy laser device which does measure it.Is it quite rare to get this measured then Derek? I just took it for granted they all did it I guess?
Forgot to mention the rake as well for the OP's benefit(20-25mm seems to work for me) which certainly seems to improve high speed stability but obviously only adjustable with sdjustable height shocks.

[Ab Shocks]

The AJP Griff said:

But thats just it,castor isnt fixed and is adjustable,am I the only one bothering then?.I dont know what my garages machine is but its some fancy laser device which does measure it.Is it quite rare to get this measured then Derek? I just took it for granted they all did it I guess?
Forgot to mention the rake as well for the OP's benefit(20-25mm seems to work for me) which certainly seems to improve high speed stability but obviously only adjustable with sdjustable height shocks.

I would not argue with increasing rake to promote stability by chucking weight forward but it is a sticking plaster which could be cured properly by increasing castor.
I would say however that just under 4 degrees that is supplied with most Tivs is more than enough if you dont have a power rack and even if you do have power steering I wouldn't bother going past 5 degrees because its not just about stability, its also about contact point on the tyre when you turn in.
BTW, with 5 degrees of castor, 10-15mm of rake does it for me

[SSPPGG]

so if you take a car without pas, and add pas, how can you increase caster when the shims dont permit?

[Ab Shocks]

SSPPGG said:

so if you take a car without pas, and add pas, how can you increase caster when the shims dont permit?

I don't quite understand why the shims would not permit, If you have shims both sides of the stock then you should be able to move one of them.

[virgil]

SSPPGG said:

so if you take a car without pas, and add pas, how can you increase caster when the shims dont permit?

Nothing to do with pas...just how much the upper ball joint is 'behind' the lower ball joints when drawing a vertical line through the lower...

so it's moving the wishbones inner ends front/back that change castor...

[BliarOut]

I think this might be the image you were looking for...

[SSPPGG]

Ab Shocks said:

SSPPGG said:

so if you take a car without pas, and add pas, how can you increase caster when the shims dont permit?

I don't quite understand why the shims would not permit, If you have shims both sides of the stock then you should be able to move one of them.

i dont have any shims, just a single 5mm thick plate, so the upper ball joint is pushed all the way back against the wishbone.

with PAS on jag based cobra replicas ive added 2/3mm shims to move the upper joint back a little, but in the griff, thats not possible.

[TVR Dummy]

Thanks for the info, I have two shims and have put them either side of the upper ball joint, I've just carried out a full re-furb on the front wishbones with all new ball joints etc, so need to get the geometry set up.

The new upper ball joints where narrower and had the thicker shim plates, I have a none PAS car so need to keep the steering as light as possible, if I move the shims forward, to increase the castor, that will make the steering heavier, yes?

Edited by TVR Dummy on Monday 3rd September 10:20

Edited by TVR Dummy on Monday 3rd September 10:21

[DarkMatter]

TVR Dummy said:

Thanks for the info, I have two shims and have put them either side of the upper ball joint, I've just carried out a full re-furb on the front wishbones with all new ball joints etc, so need to get the geometry set up.

The new upper ball joints where narrower and had the thicker shim plates, I have a none PAS car so need to keep the steering as light as possible, if I move the shims forward, to increase the castor, that will make the steering heavier, yes?

Yes, putting one thicker shim in front of the ball joint will make the steering feel heavier but it will also improve the 'self centering' of the steering. When I tried shims each side of the ball joint I'm sure that the steering felt a bit more vague in the straight ahead position, due to the reduced castor angle.