G40 suspension settings

[kwak82]

Can anybody assist with pointers regarding spring rates and/or geometry settings for a G40R on the road? I wanting to try softer spring rates but have found conflicting info on what is fitted as standard. The setup manual that comes with the cars states 625lbs front and 400lbs rear but the Ginetta parts list has 800lbs for front on road/GRDC car and 625lbs race car, only 450lb is listed for rear. These spring rates seem pretty high for a lightweight road car and I’m surprised the road car front rate, with the lighter alloy duratec, is listed as higher than the zetec race car? Has anybody tried any alternative rates?

[jamesG20V6]

My GRDC car was set up very aggressively for track when I got it - but it did win the championship the year before and so that explains it.

I had a full geo carried out by Track Developments who tested the springs at 800lb on the front. It also had incredible neg Camber on the front and rear. The rear was way to toe out to aid turn it but which was also contributing to a very lively back end on the road.

I had the car setup for road use and it transformed it from being a bit of pig on the road (albeit quick on track) to a bit more compliant on the road and it is now much more useable day to day than it was.

[kwak82]

Thanks for the reply. Sounds like your car was in a similar place to where mine is at the moment. Extremely pointy and great on a very smooth road but I think actually slower elsewhere as you have to slow down, no stability. The last geo setup in my records was to the standard settings which is 2.5 deg camber front, 1.5 deg rear, 1mm toe out front/1mm toe in rear, roughly 90mm ride height. Are your current settings less extreme than these? Did you leave your spring rates as they were? 800lbs sounds hugely stiff for a road car. I’m comparing to what the Elise/exige/vx220 guys are using on the road.

[jamesG20V6]

The spring rates are huge, but Track Developments commented that comparing to others is not necessarily like for like due to angle / location of damper and springs. I may drop mine lower once I have had a chance to put some road distance on it in different conditions.

I can dig out my revised spec sheet.

The other thing to consider is the damping rate - my shocks were clicked up to full, they are now running much less and it makes a difference on the road.

The ARB’s are also very stiff, I am going to uncouple mine at some point and run without to see exactly what they are doing. Again for road use they may be doing more harm than good.

[jamesG20V6]

I have found my set up sheet. This is what i am now running and it is much improved for road use. Zetec car.

Dampers (protech) 2 clicks all round ( still experimenting)

Ride height is 75mm ( was 65mm)

Camber

LF 2
RF 2
LR 1.5
RR 1.5

Castor is 6 degrees

Tracking
LR 5' In RR 5' in (10'in overall)

LF 5' In RF 5' in (10' in overall)

It has been cornerweighted at bang on 875kg and adjusted for driver with 48.6% front and 51.4% rear.


It went in with 4deg of neg camber on each wheel and 10' toe out front and back. Was a bit of an animal...

[kwak82]

Thanks for digging that out, you just helped the penny drop. I was comparing our settings and realised my setup sheet is also in degrees and minutes not millimetres. Which means my toe is similar to yours previously, 10’ at each wheel which according to the conversion charts is 1.3mm toe on a 17” wheel. I will start by trying my settings at something similar to yours and see how I get on.

[jamesG20V6]

What shocks do you have? It would be worth turning them back to ‘0’ and the adding a click or two and then giving it a try. I drove it for a few months with the shocks on the softest setting -and it was absolutely fine - before increasing them a bit.