Spring rates, Dampers, Ride height and stuff.
Discussion
I had for some time Nitron dampers with 325 springs on the front and 250 on the rear. For hill climbs with A032 rubber I ran 8 from hard all round and all was well. Then I went out and got some slicks which worked better (about half a second better) with the existing setup but wise ones said to really use them the car will have to be stiffer.
Off came the dampers, front springs transferred to the rear and 400lb ones fitted to the front, so effectively I have gone up 75lb all round.Initially the car felt slightly stiffer but horrible round a fast corner with a bump and even worse after a fast left right. I figured it was under damped and cranked on some more clicks. That made it feel better but not really any better than before. Possibly there is less body roll but I feel less confident about pushing the tyres than before.
Do you wise ones who know about these things think that it may now be “over sprung” ? And was I wrong to go up 75lb all round or should I have gone up the same in percentage terms front and rear ?
One thing I hadn’t predicted was how much lower the spring seats have to be to regain the ride height and therefore the camber settings.
I am undecided now whether to revert or stick with the new setup for the next meeting. I think what I was aiming at was reduced body roll so as to keep the rubber foot print closer to optimum.
Any comments appreciated
Off came the dampers, front springs transferred to the rear and 400lb ones fitted to the front, so effectively I have gone up 75lb all round.Initially the car felt slightly stiffer but horrible round a fast corner with a bump and even worse after a fast left right. I figured it was under damped and cranked on some more clicks. That made it feel better but not really any better than before. Possibly there is less body roll but I feel less confident about pushing the tyres than before.
Do you wise ones who know about these things think that it may now be “over sprung” ? And was I wrong to go up 75lb all round or should I have gone up the same in percentage terms front and rear ?
One thing I hadn’t predicted was how much lower the spring seats have to be to regain the ride height and therefore the camber settings.
I am undecided now whether to revert or stick with the new setup for the next meeting. I think what I was aiming at was reduced body roll so as to keep the rubber foot print closer to optimum.
Any comments appreciated
I always fully backed off the damping with stiffer springs, in my mind they oscillate far less so you dont need the dampers to 1) inhibit bouncing/launching or 2) assist the springs to do their job.
If it was me I'd set the dampers fully soft & start again, just winding them up until they do their job.
Dave
If it was me I'd set the dampers fully soft & start again, just winding them up until they do their job.
Dave
Going up to 400/325 springs on NTR shocks is well within their damping range, so like Dave I would start from scratch and I would add checking ride height to ensure you have enough suspension movement first.
Nice firm front end and compliant rear is my favorite
(oo err missus) but depending on steering rack location, you may have to get a bump steer test done on some geo gear that shows live settings because some bump-steer out, some toe-in under bump and some toe in N/s and toe out O/s.
I would add that you are now going a different route from Nitron thinking for road cars and sitting the car on a spring that limits body roll and then bringing the springs under the control of the dampers, if I haven't got base-line settings for a spring rate, I bounce them and adjust until I feel the spring is under sufficiant control and ensure enough rebound on the rear and then get it on the road to get the final settings
Nice firm front end and compliant rear is my favorite
(oo err missus) but depending on steering rack location, you may have to get a bump steer test done on some geo gear that shows live settings because some bump-steer out, some toe-in under bump and some toe in N/s and toe out O/s.I would add that you are now going a different route from Nitron thinking for road cars and sitting the car on a spring that limits body roll and then bringing the springs under the control of the dampers, if I haven't got base-line settings for a spring rate, I bounce them and adjust until I feel the spring is under sufficiant control and ensure enough rebound on the rear and then get it on the road to get the final settings
Edited by the gazman on Sunday 3rd June 11:19
I don't really understand this Steve. We have very similar set ups and yet on mine I found the stiffer springs made a very positive difference. I also find that taking the dampers up to fully hard (on a dry smooth track) works superbly. I usually have the rears a couple of clicks softer.I tried my last track day with the rear ARB disconnected which you might like to try, if you haven't alraedy. I imagine for a short sprint/hillclimb this might be a good idea as it helps rear traction. It does seem to let go a little more briskly but it's still catchable.
"smooth track", that's the difference Garry.
hillclimbs are like the ring (only 12miles shorter!) we have to lift the car and soften it, otherwise it gets jarred around all over the place and hits the stops (breaking an ARB link once).
the car needs to be compliant to absorb those big bumps (seen on vid) yet strong enough to maintain grip and ballance. also, some compliance allows weight shift which will help the loaded tyre. no weight shift at all only works on cars with Aero packages (like F1)
spring rates seem ok, so drop the dampers right off [4 0r 5]then build up, till your happiest.
let the spring do the work, dampers stop it bounding around afterwards (v simplified!)
andy
nice to see a griff out at Hclimbs!
hillclimbs are like the ring (only 12miles shorter!) we have to lift the car and soften it, otherwise it gets jarred around all over the place and hits the stops (breaking an ARB link once).
the car needs to be compliant to absorb those big bumps (seen on vid) yet strong enough to maintain grip and ballance. also, some compliance allows weight shift which will help the loaded tyre. no weight shift at all only works on cars with Aero packages (like F1)
spring rates seem ok, so drop the dampers right off [4 0r 5]then build up, till your happiest.
let the spring do the work, dampers stop it bounding around afterwards (v simplified!)
andy
nice to see a griff out at Hclimbs!
Edited by Guillotine on Monday 4th June 10:44
OK, you have convinced me to continue with the new springs at least for the next meeting. I will concentrate on getting the ride height and camber correct as it is still a little higher than pre change. Then I will try slackening the dampers off and see how that feels. With 325 rears and 6 from hard it is difficult to get off the line without tramping so possibly softening things a bit may help that.
More Griffs at Gurston would be good, then I would know if I am slow or very slow.
More Griffs at Gurston would be good, then I would know if I am slow or very slow.
Just another thought. Sorry if this is a bit basic. I found the handling a little "remote" (for want of a better expression) particularly in terms of front end feel when I first had 400lb springs. It took me a little while to regain confidence in front end grip. The reality was there was quite a bit more grip than before but it didn't feel like it. That may all sound daft and to be honest it feels so "right" now it even sounds a bit daft to me but I do have vivid memories of having to learn where the limit of grip was and it was a lot further than I had at first thought. May be you are just getting used to it? (and you need to push it harder 
)
I've hillclimbed mine at Loton and Prescott with these springs and wound the Nitrons up to something like 4 from hard front and 8 from hard rear. A bit bumpy but still plenty of grip. Probably could have done with more compliance at Loton but it didn't feel too bad.
)I've hillclimbed mine at Loton and Prescott with these springs and wound the Nitrons up to something like 4 from hard front and 8 from hard rear. A bit bumpy but still plenty of grip. Probably could have done with more compliance at Loton but it didn't feel too bad.
Garry, thanks for that, I hope your are right. Advice received elsewhere today suggests that as the car gets stiffer it becomes more difficult to drive, or perhaps I should say more difficult to drive easily. I will stick with them, but as lots have said go for slightly less damping at the rear.
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