Suspension Spring Rates for a Seven
Discussion
Evening guys!
Im looking at getting the coilover suspension for my Mac#1 next month but Im a little unsure as to what the spring rates should be front and back. Its using a CBR1000rr engine, on 13" wheels, and have been told that 275lb front and 175lb rear is what i should use.
However, Im not so sure there appropriate and saw them as being for a CEC tha a BEC. Isnt a BEC pretty much a 50/50 split with a driver ad tank of fuel?
Ay advice much appreciated!
Im looking at getting the coilover suspension for my Mac#1 next month but Im a little unsure as to what the spring rates should be front and back. Its using a CBR1000rr engine, on 13" wheels, and have been told that 275lb front and 175lb rear is what i should use.
However, Im not so sure there appropriate and saw them as being for a CEC tha a BEC. Isnt a BEC pretty much a 50/50 split with a driver ad tank of fuel?
Ay advice much appreciated!
You have no way of knowing based on the weight of the car, so don't go by spring rates that people are using on different models. A spring which suits one car may be totally unsuitable for another due to a variety of reasons. I'd ask your manufacturer for a recommended starting point, and go from there.
Also, don't worry about the 50/50 weight split. The suspension has totally different leverages front and back, so the rear won't necessarily be softer just because you have a softer spring there.
Also, don't worry about the 50/50 weight split. The suspension has totally different leverages front and back, so the rear won't necessarily be softer just because you have a softer spring there.
LaurenceFrost said:
You have no way of knowing based on the weight of the car, so don't go by spring rates that people are using on different models. A spring which suits one car may be totally unsuitable for another due to a variety of reasons. I'd ask your manufacturer for a recommended starting point, and go from there.
Also, don't worry about the 50/50 weight split. The suspension has totally different leverages front and back, so the rear won't necessarily be softer just because you have a softer spring there.
This - spring rates are dependent on the damper design and suspension design. For example some suspension designs run different ratios for wheel / damper movement, as the longer the damper stroke the more sensitive it typically is. But the downside is an increased in heat generation. Two factors which need to be balanced and the spring specced to suit the compromise. Different companies have different compromises.Also, don't worry about the 50/50 weight split. The suspension has totally different leverages front and back, so the rear won't necessarily be softer just because you have a softer spring there.
Another good example is EXE-TCs dampers for competition Porsches, Scoobies, and Evos. Their propriety damping circuit allows them to spec much softer springs than typically fitted to other makes.
Speak to MAC1.
rhinochopig said:
This - spring rates are dependent on the damper design and suspension design. For example some suspension designs run different ratios for wheel / damper movement, as the longer the damper stroke the more sensitive it typically is. But the downside is an increased in heat generation. Two factors which need to be balanced and the spring specced to suit the compromise. Different companies have different compromises.
Another good example is EXE-TCs dampers for competition Porsches, Scoobies, and Evos. Their propriety damping circuit allows them to spec much softer springs than typically fitted to other makes.
Speak to MAC1.
Yes, EXE-TC have a very different ethos to other suspension designs, and the results are amazing. Fortunately though, kit cars are much simpler beasts, and and often supplied with very simple dampers, which makes it easy to find a starting place.Another good example is EXE-TCs dampers for competition Porsches, Scoobies, and Evos. Their propriety damping circuit allows them to spec much softer springs than typically fitted to other makes.
Speak to MAC1.
I find that good spring choice gives very good initial results on where to go with the car. I normally ignore what everyone else says, work out the leverages and effective rates, and then choose a spring based on this and the weight of the car. This puts you in the right ballpark, and then it's your job to go out and test.
On the cheaper kits you may find the valving does not work with your spring choice, or is too spread apart for your liking, but this is normally a fair way down the road.
LaurenceFrost said:
rhinochopig said:
This - spring rates are dependent on the damper design and suspension design. For example some suspension designs run different ratios for wheel / damper movement, as the longer the damper stroke the more sensitive it typically is. But the downside is an increased in heat generation. Two factors which need to be balanced and the spring specced to suit the compromise. Different companies have different compromises.
Another good example is EXE-TCs dampers for competition Porsches, Scoobies, and Evos. Their propriety damping circuit allows them to spec much softer springs than typically fitted to other makes.
Speak to MAC1.
Yes, EXE-TC have a very different ethos to other suspension designs, and the results are amazing. Fortunately though, kit cars are much simpler beasts, and and often supplied with very simple dampers, which makes it easy to find a starting place.Another good example is EXE-TCs dampers for competition Porsches, Scoobies, and Evos. Their propriety damping circuit allows them to spec much softer springs than typically fitted to other makes.
Speak to MAC1.
I find that good spring choice gives very good initial results on where to go with the car. I normally ignore what everyone else says, work out the leverages and effective rates, and then choose a spring based on this and the weight of the car. This puts you in the right ballpark, and then it's your job to go out and test.
On the cheaper kits you may find the valving does not work with your spring choice, or is too spread apart for your liking, but this is normally a fair way down the road.
Chris Allenson at Z-Cars manages to do magical things with trailing arm rears on his mid engined minis that seem to defy all laws of wisdom - From that in my view it's always best to speak to the manufacturer as a starting point, as they (mostly) have the best idea of what works.
rhinochopig said:
It depends though IMO. What works for say an inboard design (fisher) may be totally unsuitable for an outboard design, yet both are still sevens (of a sort)
Chris Allenson at Z-Cars manages to do magical things with trailing arm rears on his mid engined minis that seem to defy all laws of wisdom - From that in my view it's always best to speak to the manufacturer as a starting point, as they (mostly) have the best idea of what works.
Oh yes indeed, because by its very nature, a car with inboard suspension will come back with totally different leverage ratios to that of a normal 7 chassis. In any case, you can still work out an ideal starting spring with the same method. It's just much more complicated to calculate with inboard suspension.Chris Allenson at Z-Cars manages to do magical things with trailing arm rears on his mid engined minis that seem to defy all laws of wisdom - From that in my view it's always best to speak to the manufacturer as a starting point, as they (mostly) have the best idea of what works.
You're right though - for the average user it's best to start with typical manufacturer recommendations. Typical doesn't do it for me though - but then I'm funny like that
Much like EXE-TC, I like to go a bit deeper and understand why the manufacturer recommends the springs that they do, which in turn helps you to understand the car in the first place, and where to go with it. EXE-TC have in fact been a really big help with my suspension work on the cars I have set up, so it's co-incidental you should mention them.
Edited by LaurenceFrost on Monday 18th October 14:37
LaurenceFrost said:
rhinochopig said:
It depends though IMO. What works for say an inboard design (fisher) may be totally unsuitable for an outboard design, yet both are still sevens (of a sort)
Chris Allenson at Z-Cars manages to do magical things with trailing arm rears on his mid engined minis that seem to defy all laws of wisdom - From that in my view it's always best to speak to the manufacturer as a starting point, as they (mostly) have the best idea of what works.
Oh yes indeed, because by its very nature, a car with inboard suspension will come back with totally different leverage ratios to that of a normal 7 chassis. In any case, you can still work out an ideal starting spring with the same method. It's just much more complicated to calculate with inboard suspension.Chris Allenson at Z-Cars manages to do magical things with trailing arm rears on his mid engined minis that seem to defy all laws of wisdom - From that in my view it's always best to speak to the manufacturer as a starting point, as they (mostly) have the best idea of what works.
You're right though - for the average user it's best to start with typical manufacturer recommendations. Typical doesn't do it for me though - but then I'm funny like that
Much like EXE-TC, I like to go a bit deeper and understand why the manufacturer recommends the springs that they do, which in turn helps you to understand the car in the first place, and where to go with it. EXE-TC have in fact been a really big help with my suspension work on the cars I have set up.
Shame they've stopped making them really. I can see why though - you can only make so many dampers a year and you can sell all you can make to GT and WRC teams at considerably more than joe public.
Wish I was a lottery winner as I'd love to have the cash to experiment with a circuit car chassis design using very long travel dampers with a 1:2 wheel / damper ratio. You'd probably need to water cool the damper, but it would interesting to see what - if any - improvement in small and large bump sensitivity you'd get.
rhinochopig said:
I have a set of their dampers on my Evo. The best compliment I can give them is that it drives like a car that is several hundred kilos lighter. They're a nice bunch of chaps having spoken to a couple of them when ordering mine.
Shame they've stopped making them really. I can see why though - you can only make so many dampers a year and you can sell all you can make to GT and WRC teams at considerably more than joe public.
Wish I was a lottery winner as I'd love to have the cash to experiment with a circuit car chassis design using very long travel dampers with a 1:2 wheel / damper ratio. You'd probably need to water cool the damper, but it would interesting to see what - if any - improvement in small and large bump sensitivity you'd get.
Excellent - I know EXE-TC very well - originally as a customer, but have now been working with them for some time too. I had their circuit and track suspension on my Evo 6, and my Evo 9. It's the first thing I'd do if I got another Evo too Shame they've stopped making them really. I can see why though - you can only make so many dampers a year and you can sell all you can make to GT and WRC teams at considerably more than joe public.
Wish I was a lottery winner as I'd love to have the cash to experiment with a circuit car chassis design using very long travel dampers with a 1:2 wheel / damper ratio. You'd probably need to water cool the damper, but it would interesting to see what - if any - improvement in small and large bump sensitivity you'd get.
They still make dampers for Evos, but just not fast-road anymore since it didn't fit in with where they were going as a company.
(Sorry to the thread author for the off-topic discussion)
Back on topic, on Locostbuilders there is a MAC1 section there where lots of people will be able to help you specifically with the car.
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