Let's talk Spring rates

[kyippee]

Good dampers are a hell of a thing... makes me look like I might know what I'm doing

[italyix]

I run 800/550 with true coilover in rear. Nitrons R3

Still dialing in front camber, but spring rates wise took me a few years of practice to get this combo right.

[bigjae1976]

As mentioned earlier, track surface will be a significant factor. I had 600/700 on my e46 M3 which was great on a smooth surface like Heartland Park and terrible on bumpy tracks (any track in TX).

[tsk94]

Quick follow up to my earlier post:

Had the first track day with the newly build car. Suspension performed very very well. As mentioned before I'm running 800 front and 570 on a rear coilover (1150 in divorced setup). Very good body control and extremely, uncanny like compliance over bumps and curbs. The track I run up here in Canada is quite bumping, so for people in the States that run smoother tracks I wouldn't hesitate at all to go stiffer. 900/~1250 would be very reasonable at smooth tracks for purpose built race/track E9X M3's - assuming you have a quality damper to control these springs

A lot of people seem to run quite soft spring rates, but most people are also running closer to stock cars (still full interior, no cage etc). Dogbone seems to be one of the exceptions of a fully built race/track car running relatively soft rates. But, spring rates are also largely personal preference and vary a lot depending on the handling balance you want to achieve, driving style, and other suspension modifications you've done/not done.

[nicksm3]

Originally Posted by tsk94

Quick follow up to my earlier post:

Had the first track day with the newly build car. Suspension performed very very well. As mentioned before I'm running 800 front and 570 on a rear coilover (1150 in divorced setup). Very good body control and extremely, uncanny like compliance over bumps and curbs. The track I run up here in Canada is quite bumping, so for people in the States that run smoother tracks I wouldn't hesitate at all to go stiffer. 900/~1250 would be very reasonable at smooth tracks for purpose built race/track E9X M3's - assuming you have a quality damper to control these springs

A lot of people seem to run quite soft spring rates, but most people are also running closer to stock cars (still full interior, no cage etc). Dogbone seems to be one of the exceptions of a fully built race/track car running relatively soft rates. But, spring rates are also largely personal preference and vary a lot depending on the handling balance you want to achieve, driving style, and other suspension modifications you've done/not done.

Thank you! And you are correct on what you stated.

[bigjae1976]

Originally Posted by tsk94

A lot of people seem to run quite soft spring rates, but most people are also running closer to stock cars (still full interior, no cage etc). Dogbone seems to be one of the exceptions of a fully built race/track car running relatively soft rates. But, spring rates are also largely personal preference and vary a lot depending on the handling balance you want to achieve, driving style, and other suspension modifications you've done/not done.

Well said.

I'll throw this out there, consider adjusting the differential in spring rates between front and rear. From my limited experience, changing that has more of an impact than increasing both front and rear rates. Especially for cars that have a different weight distribution vs stock.

[italyix]

@tsk94 by running stiffer springs than needed you effectively negate the purpose of the valving in the coil overs. Spring rates should be the mathematical result of your suspension geometry, weight (sprung and unsprung) and corner weights.

I got 800/550 as my end result and car handles amazingly on extreme performance tires.

If you move to slicks, then I would only tweek my valving, as car remains same weight.

Now, if you add aero then you need to increase stiffness.

I am no expert and all this info was gathered by my own research. I welcome comments and suggestion

[nicksm3]

Originally Posted by italyix

@tsk94 by running stiffer springs than needed you effectively negate the purpose of the valving in the coil overs. Spring rates should be the mathematical result of your suspension geometry, weight (sprung and unsprung) and corner weights.

I got 800/550 as my end result and car handles amazingly on extreme performance tires.

If you move to slicks, then I would only tweek my valving, as car remains same weight.

Now, if you add aero then you need to increase stiffness.

I am no expert and all this info was gathered by my own research. I welcome comments and suggestion

This is great thank you!

My car has full aero and I ran Limerock 2 days ago. I ran on my street tire and I was pushing, but the rear end of my car compresses hard right before the Uphill (if you are familiar with Limerock) and on the downhill before the straight.
I had Mathew Elsemore (mechanic) at Munich Motorsport, ride passengers ...He even said to get a stiffer rear spring. Few of my friends in Germany who run the Ring hard said the same thing just by looking at photos and video.

Such a learning curve here for me.

[ThunderMoose]

Originally Posted by nicksm3

This is great thank you!

My car has full aero and I ran Limerock 2 days ago. I ran on my street tire and I was pushing, but the rear end of my car compresses hard right before the Uphill (if you are familiar with Limerock) and on the downhill before the straight.
I had Mathew Elsemore (mechanic) at Munich Motorsport, ride passengers ...He even said to get a stiffer rear spring. Few of my friends in Germany who run the Ring hard said the same thing just by looking at photos and video.

Such a learning curve here for me.

Videos?

[nicksm3]

Originally Posted by ThunderMoose

Videos?

Sure thing...some in my IG: ALCHEMIST_NICKZAK

or my YouTube:

[Z33KLF]

love all the info in this thread!

[Bartledoo]

Just to add to this thread…

According to the thread linked below, the E92 M3 GT4 spring rates are:

Front: 914/1027/1142 lb/in
Rear (*true coilover): 743/857/971 lb/in
Supposedly with a stiffer rear bar.

https://www.m3post.com/forums/showthread.php?t=358641

My rates are 628f and 1120r, with Hotchkis front and rear bars both set on soft. I would go stiffer, as my contact patches running sticky tires are clearly not ideal (this car is tall and heavy), but I’m running KW Clubsports. Balance is perfect for me though.