spring rates........ Help!!!
Discussion
hi guys im having a custom nitron suspension setup being made at the moment, they've called me and asked me to specify what spring rates i'd like, at this point im confused, lol!!
After much research it seems 500/600 is a good mixed track and road compromise, however after speaking to nitron they feel this will be bone shaking.... which is definatly something i dont want, infact for me compliance is the key!!
i asked nitron to come up with a setup thats compiant for the road but aswell something that suitable for track work and maybe tweek the valving to get that ride/handling/stiffness balance, so im wondering if anyone has experience with spring rates!!
Help point me in the right direction R.e Spring rates.
cheers guys
After much research it seems 500/600 is a good mixed track and road compromise, however after speaking to nitron they feel this will be bone shaking.... which is definatly something i dont want, infact for me compliance is the key!!
i asked nitron to come up with a setup thats compiant for the road but aswell something that suitable for track work and maybe tweek the valving to get that ride/handling/stiffness balance, so im wondering if anyone has experience with spring rates!!
Help point me in the right direction R.e Spring rates.
cheers guys
I'm going to guess that it will be for your z4? If so I would definitely go for around 500/600 rather than anything softer.
Nitron recommend 400front350rear for TVR Cerbera suspension and most people find this way too soft and end up upping the rates.
Too soft a spring rate is a nightmare because you end up stiffening the ride with the dampers, effectively getting the car to ride on the damper rather than the spring.
Good luck!
Duncan
Nitron recommend 400front350rear for TVR Cerbera suspension and most people find this way too soft and end up upping the rates.
Too soft a spring rate is a nightmare because you end up stiffening the ride with the dampers, effectively getting the car to ride on the damper rather than the spring.
Good luck!
Duncan
Custom spring rates are a bit of a black art if doing it from the hobbyist perspective.
Join whatever owner club is relevant to your car and start post the question on there. To give you an idea, I needed some custom wound springs for my MTB tandem. I ended up with about 10 different springs until I found the perfect combo, which gave sufficient sag, and yet were compliant enough.
Rule of thumb is start with the known and work from there on in. If you've increased unpsrung mass, then up the spring-rate. Reduced, then go down. Decreased the sprung weight, then reduce the spring rate.
Ideally, take the car to nitron and get them to do it. It may be cheaper in the long run.
Join whatever owner club is relevant to your car and start post the question on there. To give you an idea, I needed some custom wound springs for my MTB tandem. I ended up with about 10 different springs until I found the perfect combo, which gave sufficient sag, and yet were compliant enough.
Rule of thumb is start with the known and work from there on in. If you've increased unpsrung mass, then up the spring-rate. Reduced, then go down. Decreased the sprung weight, then reduce the spring rate.
Ideally, take the car to nitron and get them to do it. It may be cheaper in the long run.
DuncanM said:
I'm going to guess that it will be for your z4? If so I would definitely go for around 500/600 rather than anything softer.
Nitron recommend 400front350rear for TVR Cerbera suspension and most people find this way too soft and end up upping the rates.
Too soft a spring rate is a nightmare because you end up stiffening the ride with the dampers, effectively getting the car to ride on the damper rather than the spring.
Good luck!
Duncan
Not always a bad thing - depends on the damper design. EXE-TC (the chaps who build Loebs dampers) provide softer springs than their competitors and are regarded as some of the finest dampers in the world. I have their "poverty" spec dampers on my Evo and they are simply amazing bits of kit - and I've had nitrons in the past.Nitron recommend 400front350rear for TVR Cerbera suspension and most people find this way too soft and end up upping the rates.
Too soft a spring rate is a nightmare because you end up stiffening the ride with the dampers, effectively getting the car to ride on the damper rather than the spring.
Good luck!
Duncan
...or you have two simple choices:
1) Measure the existing spring rates (Nitron or any decent suspension specialist will be able to do this for you, if you take them the existing springs), then make a judgement on whether you want to make them them stiffer by a percentage (if you go down this route, I would strongly suggest you keep the relative stiffness front and rear the same as it is now... ie. if you make the fronts 15% stiffer, make the rears 15% stiffer as well). Or;
2) Decide what front and rear suspension frequencies you want in cycles per minute, then do the calculations to work out the necessary spring rates to achieve them. This is rather more complicated; if you don't know how to do the calculations, or what target figures to aim for, you'll need a good basic textbook like Allan Staniforth's 'Competition Car Suspension' to guide you.
Personally, I'd go with option 1.
1) Measure the existing spring rates (Nitron or any decent suspension specialist will be able to do this for you, if you take them the existing springs), then make a judgement on whether you want to make them them stiffer by a percentage (if you go down this route, I would strongly suggest you keep the relative stiffness front and rear the same as it is now... ie. if you make the fronts 15% stiffer, make the rears 15% stiffer as well). Or;
2) Decide what front and rear suspension frequencies you want in cycles per minute, then do the calculations to work out the necessary spring rates to achieve them. This is rather more complicated; if you don't know how to do the calculations, or what target figures to aim for, you'll need a good basic textbook like Allan Staniforth's 'Competition Car Suspension' to guide you.
Personally, I'd go with option 1.
Sam_68 said:
...or you have two simple choices:
1) Measure the existing spring rates (Nitron or any decent suspension specialist will be able to do this for you, if you take them the existing springs), then make a judgement on whether you want to make them them stiffer by a percentage (if you go down this route, I would strongly suggest you keep the relative stiffness front and rear the same as it is now... ie. if you make the fronts 15% stiffer, make the rears 15% stiffer as well). Or;
2) Decide what front and rear suspension frequencies you want in cycles per minute, then do the calculations to work out the necessary spring rates to achieve them. This is rather more complicated; if you don't know how to do the calculations, or what target figures to aim for, you'll need a good basic textbook like Allan Staniforth's 'Competition Car Suspension' to guide you.
Personally, I'd go with option 1.
woa even option one is complicated for me, lol!!1) Measure the existing spring rates (Nitron or any decent suspension specialist will be able to do this for you, if you take them the existing springs), then make a judgement on whether you want to make them them stiffer by a percentage (if you go down this route, I would strongly suggest you keep the relative stiffness front and rear the same as it is now... ie. if you make the fronts 15% stiffer, make the rears 15% stiffer as well). Or;
2) Decide what front and rear suspension frequencies you want in cycles per minute, then do the calculations to work out the necessary spring rates to achieve them. This is rather more complicated; if you don't know how to do the calculations, or what target figures to aim for, you'll need a good basic textbook like Allan Staniforth's 'Competition Car Suspension' to guide you.
Personally, I'd go with option 1.
Beedub said:
nitron said 500/600 would be way to stiff?? firstly ive got to remember in in a roadsterso even though the chassis is HUGELY stiff its stiff compromised compared to the z4m coupe which has one of the stiffest platforms ever. im thinking maybe 450/500
As someone else said, this is black art. Also on such a heavily modded vehicle and used as such person taste, setup and preference are likely to come into play. Ie there isn't one single spec. I'd also say, that I suspect a lot of companies when you say road use, will always air on the side of caution and go on the softer side. As most people will be happy. If you really don't care about road manners then you need to be very clear about this.
Beedub said:
woa even option one is complicated for me, lol!!
Really?Measure spring rates and multiply by 1.15 for 115% (or whatever you choose to go with) is too complicated??
Then, to be blunt, you're better off leaving both springs and dampers well alone... I hear that BMW employ some pretty reasonable engineers, several of whom are even rumoured to possess their own pocket calculators.
Nitron make excellent dampers, but they're adjustable, so there is a definite potential for making things worse than they were to start out with, if you don't properly understand what it is you're trying to achieve.
Sam_68 said:
Really?
Measure spring rates and multiply by 1.15 for 115% (or whatever you choose to go with) is too complicated??
Then, to be blunt, you're better off leaving both springs and dampers well alone... I hear that BMW employ some pretty reasonable engineers, several of whom are even rumoured to possess their own pocket calculators.
Nitron make excellent dampers, but they're adjustable, so there is a definite potential for making things worse than they were to start out with, if you don't properly understand what it is you're trying to achieve.
it was a joke.... ;-) im just trying to understand what my car needs in terms of spring rates, ive pretty done the build for my z4m, so measuring the stock spring rates is no problem, the problem i have is .... ok for example if the stock ones are 250/250 which the z4m is notoriously a stiffly sprung car but feels fine to me, i still dont know whether 500/500 is going to sufficient or too much as im not a suspension engineer, i guess ill just have to trust nitron. Thankyou for you post.Measure spring rates and multiply by 1.15 for 115% (or whatever you choose to go with) is too complicated??
Then, to be blunt, you're better off leaving both springs and dampers well alone... I hear that BMW employ some pretty reasonable engineers, several of whom are even rumoured to possess their own pocket calculators.
Nitron make excellent dampers, but they're adjustable, so there is a definite potential for making things worse than they were to start out with, if you don't properly understand what it is you're trying to achieve.
thinfourth2 said:
I think springs are cheap compared to dampers
So trust nitron and if they end up too soft/stiff then its not the end of the world to swap them over
The springs are cheap, it's the labour to remove, re-fit, geo, repeat until satisfied that starts to add up.So trust nitron and if they end up too soft/stiff then its not the end of the world to swap them over
OP don't forget to tell Nitron whether you have increased or decreased unsprung mass with your mods - are the wheels / brakes now heavier than before?
Personally I'd go with an off the shelf system that has been proven to work with the Z4. Someone like KW would be my choice as they've been fiddling with BMWs for years and they do a bespoke bolt-on damper/spring combo.
rhinochopig said:
The springs are cheap, it's the labour to remove, re-fit, geo, repeat until satisfied that starts to add up.
OP don't forget to tell Nitron whether you have increased or decreased unsprung mass with your mods - are the wheels / brakes now heavier than before?
Personally I'd go with an off the shelf system that has been proven to work with the Z4. Someone like KW would be my choice as they've been fiddling with BMWs for years and they do a bespoke bolt-on damper/spring combo.
the brakes and wheels loose unpsrung mass, i think i'll leave it to nitron to sort spring rates :-) im sure they'll get it right, im pretty confident they will :-)OP don't forget to tell Nitron whether you have increased or decreased unsprung mass with your mods - are the wheels / brakes now heavier than before?
Personally I'd go with an off the shelf system that has been proven to work with the Z4. Someone like KW would be my choice as they've been fiddling with BMWs for years and they do a bespoke bolt-on damper/spring combo.
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