Aftermarket Spring Rate Discussion

[noxredna]

Moderator note: please discuss your spring rates and feedback in this post

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Sorry, was not clear but I could get a range of spring rates from TC Kline with the D/A coilover instead of the standard 500F 800R from KW Clubsport.

There's a good opportunity to run stiffer rear spring rates, 900 or even 1000.. the car is pretty heavy

Originally Posted by JAJ

I'm not sure I understand this statement - could you explain please? The KW's use 60mm race springs and I believe the TCK system uses 64mm (2.5") racing springs. While some spring manufacturers have a wider range of rates and lengths in one size or the other, across the race spring marketplace (Eibach, H&R, VVS, Swift, KW and so on) you can pretty much get the same rates and lengths in either size. That sounds like pretty much the same range of choices. Am I missing something?

I have my KW Clubsport suspension set up 10mm lower than stock with the factory camber, caster and toe settings exactly. For track days I drop the front camber down to -2.1 degrees, which gives me a bit of toe-out. According to the dealer's laser alignment system, the KW camber plates deliver very repeatable toe-in and camber adjustments as you switch back and forth.

[JAJ]

Originally Posted by noxredna

Sorry, was not clear but I could get a range of spring rates from TC Kline with the D/A coilover instead of the standard 500F 800R from KW Clubsport.

There's a good opportunity to run stiffer rear spring rates, 900 or even 1000.. the car is pretty heavy

OK - got it now! Thanks!

In a perfect world I'd run a much higher rear rate than 800# at the rear. My excuse is that my Clubsports came that way - why did you select 800# when you could have gone higher?

[noxredna]

Honestly - I was afraid of the daily drivability of the car.. Even though i'm tracking quite often nowadays, I still have to drive it around SF city and commute work with it every single day.

After the installation though, the car rides very very smooth and compliant on city roads - you don't really compromise drivability at all with these coiovers and even with the 500/800 spring rates.

I might try out stiffer rates in the rear and work on the alignment a little more. I believe I can dial more camber into the car but had to reduce it because the car was very loose under hard high-speed braking...

Also, I discussed this with Harold at HP Autowerks who's been prepping my car for this past weekend's race and he said he has no issues to switch out my spring rates to a higher rate (900/1000) anytime. TC Kline share a storage area in the same compound as his shop so he has access to a lot of their stuff/knowledge... also they are the master distributors for SWIFT springs and they give pretty good deals on those.

Some pics of installation and the car this past weekend's race, will do a full write-up soon.

[RickyBobby]

I'm glad I'm not the only one running track rates. I need someone besides me to determine if the subframe will need reinforcing like previous generations

[rzm3]

So here are the spring rates I know people have used:

800/1100: user reports rear could be slightly softer
550/900: user seems to be happy but needs more testing
500/800: the kw rate which many have tried and seems to be a good balance
500/750: slightly understeer but a good, safe set up

Again, there is no magical formula. The set up could vary based on the track you are driving on, damper settings, and driver preference.

[JAJ]

noxredna: thanks for posting the pix and your rationale for the spring choice. I spent a lot of time and research on what rates to choose (KW will make to order, or if not, they'll sell you the parts and you can assemble it yourself) and in the end I decided to stick to what KW chose. They'd done testing I could never do, so I just went with it and it's working well for me.

Your comments on daily driving your DA coilover setup were interesting. I don't dd my M; my car gets mostly highway time or track time, with a small bit of city driving. I put my KW's on in May, but for a variety of reasons I'd only ever driven it on stock 19's or on R-comps until yesterday. You could tell that the springs were stiffer, but from an NVH standpoint the car was very close to stock. Last weekend, I finally got around to putting on my set of stock 18" PS2's, then yesterday I took the car out to run around town and do a bunch of errands. What a difference! It rides like a limousine on the 18" PS2's. It's firm, but not even a little bit choppy or harsh. As a dd, it would be more than fine. I won't say it's better than stock, but it's certainly no worse.