Spring rates for Race Griff
Discussion
Hi
My 6.2 Griff runs about 1000lb per inch on the front and about 450 on the rear with an uprated anti roll bar. 1" diameter and rose jointed
It stll seems too soft at front rolling considerably under full load.
Has any one got experience of what spring rates to use? Is any one using much harder springs? It weighs 1068 Kg.
What spring rates do Tuscan racers use?
Many thanks
Matthew
My 6.2 Griff runs about 1000lb per inch on the front and about 450 on the rear with an uprated anti roll bar. 1" diameter and rose jointed
It stll seems too soft at front rolling considerably under full load.
Has any one got experience of what spring rates to use? Is any one using much harder springs? It weighs 1068 Kg.
What spring rates do Tuscan racers use?
Many thanks
Matthew
Those spring rates are evidently much higher than road rates and therefore getting to an alien sphere of my knowledge, I would however say that 1k fr and 400r does seem somewhat out of balance? Wouls stiffening the rear springs not help to stop the front dive, or is it that going stiffer on the rear causes more traction issues?
Thank you
Traction is all important. It is good as it is and I am reluctant to compromise it. If you look at race air cooled 911 or escorts and most powerful rear drive saloon cars then they are set up soft at the rear with all roll stiffness at the front. They will lift an inside front wheel on hard cornering. I think i need to work towards that but I am shocked how much spring is required. THe other option I supose is a stronger still anti roll bar
Best Wishes
Matthew
Traction is all important. It is good as it is and I am reluctant to compromise it. If you look at race air cooled 911 or escorts and most powerful rear drive saloon cars then they are set up soft at the rear with all roll stiffness at the front. They will lift an inside front wheel on hard cornering. I think i need to work towards that but I am shocked how much spring is required. THe other option I supose is a stronger still anti roll bar
Best Wishes
Matthew
when you upped your spring rate to that, did you have the shox re-valved to suit the heavier springs, or is the valving still as it was?
I believe Andy has 1200lb springs up front on his Griff.
I have 500lb springs up front and my valving was custom spec'd by Nitron. When you push the front of our cars down, his moves quite easily whereas mine is like a rock in comparison.
I believe Andy has 1200lb springs up front on his Griff.
I have 500lb springs up front and my valving was custom spec'd by Nitron. When you push the front of our cars down, his moves quite easily whereas mine is like a rock in comparison.
Thank you
Yes I was considering going to 1200 so perhaps I'm not going mad!
Dampers are Ohlins and have been revalved. Damping needs to match the spring as you say. However, In my (very)limited understanding, damping will have little effect on steady state roll in cornering. Increased bump damping makes the car harder on the bumps and will roll slower. Increased rebound may prevent recovery of spring length after bump and there fore increase effective spring rate as ride height is lost ???
Yes I was considering going to 1200 so perhaps I'm not going mad!
Dampers are Ohlins and have been revalved. Damping needs to match the spring as you say. However, In my (very)limited understanding, damping will have little effect on steady state roll in cornering. Increased bump damping makes the car harder on the bumps and will roll slower. Increased rebound may prevent recovery of spring length after bump and there fore increase effective spring rate as ride height is lost ???
I think your rear springs are too light compaired with most proven setups i've seen, which seem to run 20-25% lighter springs on the rear.
One main disadvantage you will have with a softer setup at the rear is that weight tranfer forward will be much quicker making your front have to work much harder to cope under heavy braking. Stiffening up the rear will be a compromise for traction, but it will reduce the speed of weight transfer forward, as well as body roll at the rear affecting the front in cornering.
One main disadvantage you will have with a softer setup at the rear is that weight tranfer forward will be much quicker making your front have to work much harder to cope under heavy braking. Stiffening up the rear will be a compromise for traction, but it will reduce the speed of weight transfer forward, as well as body roll at the rear affecting the front in cornering.
Edited by Bluebottle on Saturday 7th August 09:59
Hi Matt, In our Griff racer (#93 that won class in pretty much all we entered last year) we don't run them that high, but also we run the back stiffer than you! I can't remember exactly at the moment but 800(or maybe 900)/600 seems to ring a bell. It's been that long since we looked at it given personal circumstances at the moment I can't remember, though we will be starting work on it in the next week or so - Dad wanting to get back out for a couple of fun races if possible this year! Drop me an e-mail if you want me to check for you!
Also, what way are you dampers adjustable? It could be that it's not so much the springs but the damper rate that needs adjusting?
Also, what way are you dampers adjustable? It could be that it's not so much the springs but the damper rate that needs adjusting?
We run standard at the front and don't run one on the rear. We've got a lot of rubber on the floor too (running Dunlop 285/640(?)/18 slicks all round) and although we do get body roll, it's nothing too major... Plus with stiffer springs at the rear there will be less movement when you accelarate, equating to less transfer when you brake generally. We've got the car set up using the adjustments on the dampers too (3 way adjustable) and while it may not be set up to it's full potential as yet, dad is certainly happy with it the last time he was out! (Took a good chunk off the class lap record around Castle Coombe!!)
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