Ohlins updated it's R&T coil-over for our car

[jamal]

Originally Posted by idkwhatimdoing

I am running the MP20 currently and I have to say the spring rates are very well matched to the car.
Stiffer doesn’t really mean better.



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Yeah, notice the rates are backward? Stock has stiffer rear springs. ohlins uses stiffer front springs.

[nikitopo]

Originally Posted by jamal

Yeah, notice the rates are backward? Stock has stiffer rear springs. ohlins uses stiffer front springs.

New cars have stiffer front springs and softer rear springs. Anyway, springs rates is a subjective matter. You might have a suspension with much stiffer springs and poor damping quality (especially rebound) and get a similar or even worse performance.

[jamal]

It's not subjective, it's physics. If you are at a track trying to improve lap times you use a stopwatch, measure tire temperatures, and adjust from there. These are called "road and track" coilovers, right? If you actually go to the track with these things you'll probably get a lot of push and cook the front tires.

There is some leeway depending on things like the swaybars and power output and driver feedback but as a starting point it's a really good idea to have the rear springs a touch stiffer to balance the suspension stiffness relative to the weight distribution of the car.

A 3k (168lb) rear spring is softer than stock and the actual rate at the rear wheel is only around 1.7 as previously mentioned due to the suspension design. Meanwhile the front 4k spring gives a wheel rate that is actually around 4k.

So think of it that way, where the front springs are 4k and the rears are 1.7. The car has a close to equal weight distribution and the same size front and rear tires and not very much power. It doesn't add up very well from a handling point of view but it sure will ride comfortably.

At the same time, if you have these and love the ride and handling, great. But don't be surprised to see much higher front tire temps if you actually measure.

[Andyxin]

It will be really interesting if Ohlins shows us why they chose 4K 3K spring rate. I agree that it is all about physics not magic but since Ohlins is one of the biggest names in motorsports, I think they know what they are doing. I'm not saying 4K 3K is great but want to hear from Ohlins.

[idkwhatimdoing]

Originally Posted by Andyxin

It will be really interesting if Ohlins shows us why they chose 4K 3K spring rate. I agree that it is all about physics not magic but since Ohlins is one of the biggest names in motorsports, I think they know what they are doing. I'm not saying 4K 3K is great but want to hear from Ohlins.

Agreed.
If not, the biggest name.
They’ve been very successful with the GT4 class cars on their suspension, and I think that says something.


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[nikitopo]

Originally Posted by jamal

It's not subjective, it's physics.

Yes it is subjective, because you have measurements only for the springs. I am aware that other top end manufacturers are using an additional spring inside the damper. They call it rebound spring and in fact the stiffness of this adds up to the external spring rate. I am not sure if Ohlins uses the same method and I don't think they will share their secrets. Unless someone opens a damper and checks the internals. You cannot really judge the performance of a suspension by comparing just the spring rates.

[jamal]

That's a good one. But no, these ohlins do not have secret extra springs inside the dampers. They even provide cutaway diagrams on their website to explain how the "dual flow valve" works. Although yes they're pressurized but it would take a crazy amount to make a difference on these since the piston rods are so small. (JRZ for example uses big shafts, partly because they like the shock to provide a bit of "platform" and also to make air pressure changes more significant).

Think about steady state cornering on a smooth road- the dampers are not doing much and the balance is determined mostly by the springs. You can't fix that with shocks. So look at the weight distribution, look at the motion ratios, look at the stock spring rates. That gives you a pretty good guideline on where to go with coilovers. Now why would you go to something completely off from that?

Actually that last part is sort of a real question because so many manufacturers do it, but i can come up with some pretty good reasons.

[churchx]

Shock dynos might tell a bit more ..

[Racecomp Engineering]

They used such soft rates because they were focusing on ride comfort.

- Andrew

[fatoni]

Originally Posted by jamal

It's not subjective, it's physics. If you are at a track trying to improve lap times you use a stopwatch, measure tire temperatures, and adjust from there. These are called "road and track" coilovers, right? If you actually go to the track with these things you'll probably get a lot of push and cook the front tires.

There is some leeway depending on things like the swaybars and power output and driver feedback but as a starting point it's a really good idea to have the rear springs a touch stiffer to balance the suspension stiffness relative to the weight distribution of the car.

A 3k (168lb) rear spring is softer than stock and the actual rate at the rear wheel is only around 1.7 as previously mentioned due to the suspension design. Meanwhile the front 4k spring gives a wheel rate that is actually around 4k.

So think of it that way, where the front springs are 4k and the rears are 1.7. The car has a close to equal weight distribution and the same size front and rear tires and not very much power. It doesn't add up very well from a handling point of view but it sure will ride comfortably.

At the same time, if you have these and love the ride and handling, great. But don't be surprised to see much higher front tire temps if you actually measure.

He doesn't understand the difference between Mac struts and double wishbone. You're wasting your time.

[Andyxin]

Originally Posted by Racecomp Engineering

They used such soft rates because they were focusing on ride comfort.

- Andrew

Öhlins listed in RCE website has 6K6K springs according to the description. Is this a MP 20 with aftermarket springs? I’m interested in getting one if spring rates are 6K6K

[churchx]

Andyxin: 6K/6K is of original(now discontinued) SUS MI20 R&T kit. Later on it was changed to MP20 (and now MP21) with 4K/3K rates and making camberplates optional. Some had said, that dampening on these is exactly same as on first kit, but i don't know that 100%, as always thought that dampening should match spring rates, and Ohlins is among top vendors, so is it really so?
So those rates most probably are for old/discontinued, which you can find only used, and if some shop still lists it, then very probably shop hasn't updated availability info.

[nikitopo]

Originally Posted by fatoni

He doesn't understand the difference between Mac struts and double wishbone. You're wasting your time.

Let some others talk that have changed their suspension. I believe your brz is still stock? Besides, he mentioned that when you are in a turn, the dampers are not doing much. This is enough for me and not worth it to continue the discussion.

[Racecomp Engineering]

Originally Posted by Andyxin

Öhlins listed in RCE website has 6K6K springs according to the description. Is this a MP 20 with aftermarket springs? I’m interested in getting one if spring rates are 6K6K

Sorry that's the old version of the coilovers...need to update the site.

- Andrew