997.1 GT3 Spring Rates
Discussion
v8ksn said:
Yep! Chris agrees with you. Ohlins recommended 90Nm front and 140Nm rear. Chris said these would be way too stiff for my desired set up so recommended the 60Nm and 120Nm rates. These are perfect for my for road use but obviously way too soft for track.
how far can you go away from oem Ohlins rates without re-valving ? as your fronts are quite a bit softer .would they be really way too soft for track over oem cars which are tracked already ? you have harder springs and can add a few clicks on the bump/rebound.
the Cayman R tracks ok on it's shocks/springs imo hence not wanting to go harder just adjustment to balance the car how I like them to drive.
all the Lotus guys as an example have gone Nitron and custom vavling and it seems easy to re-valve.
As 911R says, the spring rates that you end up with will need to be matched to the valving on the shocks. if the sping is too soft, the shocker will effectively take over and if it's too hard, the spring wll take over. It's very tough picking the correct compromise. You need to think very hard about what surfaces you will be wanting to maxmise your enjoyment on. Bumpy B roads, smoother A roads or track. A softer spring rate will obviously favour a bumpy B road but that spring/damper combination will be horrible on the track.
Always a tough one. I always default to somewhere between track and smooth A road for something like my 964 and track for something like a 996RS
Always a tough one. I always default to somewhere between track and smooth A road for something like my 964 and track for something like a 996RS
Steve Rance said:
As 911R says, the spring rates that you end up with will need to be matched to the valving on the shocks. if the sping is too soft, the shocker will effectively take over and if it's too hard, the spring wll take over. It's very tough picking the correct compromise. You need to think very hard about what surfaces you will be wanting to maxmise your enjoyment on. Bumpy B roads, smoother A roads or track. A softer spring rate will obviously favour a bumpy B road but that spring/damper combination will be horrible on the track.
Always a tough one. I always default to somewhere between track and smooth A road for something like my 964 and track for something like a 996RS
when I ran my Exige on the posh 46mm Ohlins I had on that, I tended to only have to turn down the rebound 3 clicks for the road and it was ok ish to drive to and from the track in.Always a tough one. I always default to somewhere between track and smooth A road for something like my 964 and track for something like a 996RS
hence I dislike 1 way shocks, I did a sprint also In the dry and got the fastest time, then it rained and the back was too exciting, 2 clicks off the bump this time at the rear, I then got the fastest wet time.
3 ways blow my mind and you can make things worse as a novice, 1 ways seem pointless if you cannot do bump and rebound on their own, but a nice 2 way set about 20% stiffer would be great.
every set of shocks though seems double or more on the spring rates and no one seems to offer a re-vavle to suit !
I think being able to dial off rebound alone for road use is very helpful, if def smoothed my Exige loads.
At the end of the day I had a road set up, a track dry set up and a track wet set up, it was great. I miss this on my Porkers.
Porsche911R said:
when I ran my Exige on the posh 46mm Ohlins I had on that, I tended to only have to turn down the rebound 3 clicks for the road and it was ok ish to drive to and from the track in.
hence I dislike 1 way shocks, I did a sprint also In the dry and got the fastest time, then it rained and the back was too exciting, 2 clicks off the bump this time at the rear, I then got the fastest wet time.
3 ways blow my mind and you can make things worse as a novice, 1 ways seem pointless if you cannot do bump and rebound on their own, but a nice 2 way set about 20% stiffer would be great.
every set of shocks though seems double or more on the spring rates and no one seems to offer a re-vavle to suit !
I think being able to dial off rebound alone for road use is very helpful, if def smoothed my Exige loads.
At the end of the day I had a road set up, a track dry set up and a track wet set up, it was great. I miss this on my Porkers.
Yep. Thats an ideal scenario - but you need to know what you are doing on set up or you can go down the wrong route and things get a lot worse. The great thing about the Exige is it's light and that makes things easier. It's more difficult to get a wide range of options on a heavier car. I'd agree that seperate bump and rebound adjustment is pretty essential. one thing i hate is when a damper manufacturer offers 50 or so different settings. That can take forever to set up. 10 or 12 is fine. It makes it much easier for an inexperienced driver to feel the difference between each click. Why the obsession with lots of adjustment options is beyond me. hence I dislike 1 way shocks, I did a sprint also In the dry and got the fastest time, then it rained and the back was too exciting, 2 clicks off the bump this time at the rear, I then got the fastest wet time.
3 ways blow my mind and you can make things worse as a novice, 1 ways seem pointless if you cannot do bump and rebound on their own, but a nice 2 way set about 20% stiffer would be great.
every set of shocks though seems double or more on the spring rates and no one seems to offer a re-vavle to suit !
I think being able to dial off rebound alone for road use is very helpful, if def smoothed my Exige loads.
At the end of the day I had a road set up, a track dry set up and a track wet set up, it was great. I miss this on my Porkers.
Steve Rance said:
To get round this i'm fitting 17 inch road wheels to my 964 and a tyre with a high side wall. That will make the ride a lot more compliant. Modern ultra low profile tyres are not a great idea on the UK road system. I'll use the 18's with cup 2's for the track
You're absolutely right. My mate, who runs the local friendly MOT station says that when the trend for rock-hard, M-Sport suspension and low profile tyres took off with BMWs, they began to see routine cases of cars needing new wishbones by 60k miles.Digga said:
v8ksn said:
The ride is pretty perfect for fast A and B roads. It now flows with the road as opposed to fighting it but its too soft for track work. I can set the dampers to fully stiff but then its a little skittish.
You generally find with dampers that there's only a small amount of actual, usable adjustment within the 'theoretical' number of clicks/settings. Too much damping with too low a spring rate and the car sits of the damper, not the spring which, as you say, does not work!Slippydiff said:
Ohlins are fast gaining a reputation for specifying spring rates that are waaaay too stiff for British roads (and that’s about as straight from the horses mouth as you can get...)
It's not just Ohlinshttp://www.evasivemotorsports.com/mm5/merchant.mvc...
not even close. When you start using really high quality dampers, THEN you can run soft springs and “prop” the car up with the dampers, and this is precisely what I did with the ex-R/RSR Ohlins 3 ways on the GT3. You can also change spring rates by fairly hefty margins and have sufficient adjustment left to control them with the existing damper valving.
Ohlins have pulled off quite a feat making all and sundry believe that buying their “budget” range of dampers will all of a sudden bestow their cars with levels of damping experienced with dampers costing three times as much (though I’m not suggesting Digs or V8ksn have fallen into this trap), but plenty on US forums seem to think that a bit of gold anodising and an Ohlins sticker mean they’ve miraculously gained WRC standard damping for a tenth of the price...
The R&T’s have some clever bypass valving, but the rest of the dampers components won’t be manufactured to the tolerances a high end damper requires.
Slippydiff said:
not even close. When you start using really high quality dampers, THEN you can run soft springs and “prop” the car up with the dampers, and this is precisely what I did with the ex-R/RSR Ohlins 3 ways on the GT3. You can also change spring rates by fairly hefty margins and have sufficient adjustment left to control them with the existing damper valving.
Thats interesting. Goes against everthing that ive been told by race engineers. But then in general in terms of scope, the track - being a pretty constantly flat surface does not offer the scope challenges of a road damper. I've not heard of anyone successfully achieving this before. I suppose it depends on the range of adjustment that the damper offers and effectiveness of the dampng across the range. As you say, there is a big diffrerence between a low range damper and a high range damper. My KW clubsports are reasonbly good but they are not a high end solution. Steve Rance said:
Thats interesting. Goes against everthing that ive been told by race engineers. But then in general in terms of scope, the track - being a pretty constantly flat surface does not offer the scope challenges of a road damper. I've not heard of anyone successfully achieving this before. I suppose it depends on the range of adjustment that the damper offers and effectiveness of the dampng across the range. As you say, there is a big diffrerence between a low range damper and a high range damper. My KW clubsports are reasonbly good but they are not a high end solution.
Hi Steve, my Ohins did duty on a 3.9 litre Mk 1 996 GT3. I passengered in the car at the 2017 RS day at Oulton, the driver is one of the quicker gentleman who frequently tracks his car’s, running spring rates less than 10% stiffer than standard, his car was as quick as a well driven Gen 2 997 GT3 RS.Theoretically that shouldn’t be possible with such soft spring rates, but the car felt massively planted (and rode the kerbs beautifully)
I suggested to the driver that he should wind a bit of low speed compression on, but he said he knew how the car handled and was happy to forego the last bit of performance on corner exit, for the peace of mind the current settings gave him.
I’m sure that doubling the spring rates would have made it into an even more competent track weapon, but at the expense of it’s ability to soak up pretty much anything our A/B roads could throw its way.
My summation stands, REALLY good quality dampers allow you to have a superlative, compliant road set up, AND also allow you to have a superbly handling car should you also wish to venture out on track (though ultimate track performance will be slightly compromised) though not to anything like the degree V8skn is suggesting he’s experiencing with his R&T set up.
Edited by Slippydiff on Tuesday 15th May 12:31
Steve Rance said:
Thats interesting. Goes against everthing that ive been told by race engineers. But then in general in terms of scope, the track - being a pretty constantly flat surface does not offer the scope challenges of a road damper. I've not heard of anyone successfully achieving this before. I suppose it depends on the range of adjustment that the damper offers and effectiveness of the dampng across the range. As you say, there is a big diffrerence between a low range damper and a high range damper. My KW clubsports are reasonbly good but they are not a high end solution.
Just to pick a further bone out of this Steve. Your comment "Goes against everything that I've been told by race engineers" tells all.As I've said previously on here, I purchased a brand new set of Mk1 996 GT3 springs and handed them to the guy who was about to build the Ohlins. I told him to dyno them and let me know their rates (difficult because either the fronts or rears (can't remember which) are progressive rate items). When he told me he'd dyno'd them and gave me the figures, I told him that's the rates we'd be using...
he laughed... but he stopped laughing when he all too quickly realised I wasn't, AND that I was deadly serious.
He then told me they'd be "waaaay too soft". I asked him how so when they were near perfect with the OE Bilsteins...?
"They'll be hopeless on track" he replied. I told him that was OK as the car wouldn't be used on track !!
Once he'd conceded these were the rates we'd be using, he made one final caveat "If they're too soft you'll have to have them re-sprung and re-valved too, and it'll be at your expense"
"Fine" I said as I walked out of the workshop without so much as backward glance
He accompanied me to carry out the final adjustments to the bump and rebound settings, and when we got back from one of my favorite stretches of bench-marking tarmac, he admitted just how good the set up was. As I've said in earlier post, this very same setup worked around Oulton too ...
In my very humble opinion, race and damper engineers rightly focus on make cars go as fast as possible around circuits, but making a car work well on our unique A & B roads is a very different discipline altogether, and something Chris Franklin at CG seems to be rather adept at.
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