Coil over spring rates
 

Hi. I’m trying to find someone that can give me some starting point on spring rates for a fast road 32s

450/500lbs is a good starting point. Its what spec boxsters use and frankly, with my feal coilovers, they are very comfy. As my car is almost purely a track car at this point, I'll likely upgrade to 600/650

What does it weigh?

This thread has a lot of discussion about various spring rates and their effect.
http://986forum.com/forums/performance-technical-chat/27222-m030-spring-rates.html

Different drivers like a different feel so there is no one perfect setup. BSR Spec race cars run 450/500 and a lot of guys like it but I don't want a car so tied down. Too much spring on a car without LSD results in wheel spin on corner exit. Wheel spin is slow.

On my 986 BSX dual purpose Time Trial car I went with 270F/370R and it was *just enough* spring to reduce roll and make quicker transitions while still having full grip on corner exit. That car was good for 5 TT Championships so it worked pretty well and was still reasonably comfy on the street. YMMV

Topless, I'm also curious about this topic. I learned to appreciate softer from a couple of Lotus'. What tires and bars did you use? Weight? Thanks.

The car was right at BSX class weight with no gas, 2950# w/driver

Tires: NT-01 225/255 (class tire)
GT3 Front sway, full soft
Tarret rear sway, full soft (disconnect for rain)

I sometimes ran 255 square on tight tracks or AX and would take a notch or 2 on the front sway to balance the car.

It's also not just about spring rate. The type of shocks make a difference as well. I was very concerned with the spring rates on the Ohlins RT's (400lb front and 450 rear or something like that) I put in my Cayman as its my street car. Surprisingly enough, due to the valve design of the Ohlins - they were more compliant than the stock springs and shocks. My Boxster runs 700/800 as it's track only - and the Moton 2 ways were built for those rates.

Absolutely! Spring rate, dampening, ride height, tire choice, sways, all up weight, and setup are all important pieces of the equation that must be considered for best results. Changing one or two elements without considering the impact on other variables will sometimes make the suspension worse... much worse.

As instructors we spend a lot of time in other people's cars at the track. My impressions:
-Best by far: A well-tuned performance suspension with a pro setup.
-Next best: Bone stock with pro performance alignment.
-Often worse: DIY shade-tree suspension changes without an experienced pro connecting all of the dots.

I agree with Dave. ^^^ I also campaigned a BSX Boxster and posted 16 Time Trial wins and 2 track records.

I've driven Boxster's on the street and the race track with stock, 200, 270/370, 450/500, 650, and 800 spring rates. As others have said, there is no single perfect spring rate, because the springs have to match the rest of the components, setup, etc.

For any street/road going car, I would say that the BSX setup with 270/370 springs (the Bilstein PSS9 spring that comes with the shock) is a great trade off between stiffness and compliance.

I've driven thousands of street miles (and 100 races) on the 450/500 springs in my Spec Boxster and this setup is incredibly awesome when the roads are nice and smooth, but its generally too stiff for sporty street driving because the roads are often too rough resulting in a loss of traction, especially under hard braking and hard acceleration.

Good Stuff. Wish we had a like button. Topless, thstone, either of you run a square setup? Aren't the PSS9s going the way of the Dodo bird?

Great discussion on this and some great answers. Thanks 👍

Yes PSS9s are now being replaced by more advanced struts like JRZ, Moton, and others. A timely thread as my Cayman has 70k miles, of which maybe 20k on race tracks and the struts are pretty far gone. Having discussions now with my setup shop to determine the best dual-purpose struts and springs for my weekend joyride/track steed.

RE: Running square- I ran both ways and gathered a lot of comparison data. For tight tracks and AX I found 255/255 to be a bit quicker but longer tracks with higher speeds favored 225/255 for the fastest laps. They were very close but the trends were clear. In wheel to wheel racing there are advantages to having more grip in the front for quick moves and going deeper in the braking zones. I think most BSR drivers run 255/255 for this reason, as well as the ability to rotate all 4 corners for best tire management.

Others may have different experiences with tire choice but this is what I found over 10 years with my 986.

Yes, I ran both staggered and square. I held two track records running staggered. But once I went square, there was never any reason to go back. Braking and corner entry are hugely enhanced running square. I don't think that anyone runs staggered anymore in Spec Boxster.


Yep, the PSS9 is going obsolete. The new Spec Boxster shock is an MCS unit.

Read about it here: http://986forum.com/forums/boxster-racing-forum/74751-pca-announces-new-spec-boxster-shock-package.html

The Ohlins RT's I put on my Cayman are THE best street coilovers I've ever used. While not on my Cayman, I've owned KW V2's and V3's, Penske's, Bilsteins and others and the Ohlins are far superior on the street. I'll stick with my 2Way Motons on the track.

Just had a very pleasant chat with the design engineer at Vorshlag (when I should be working). Wish I had recorded the very one sided informative discussion. I wanted to see what spring weights the Ohlins dampers can tolerate prior to damper modifications - Ohlins will only build 10n up or down, which would be about 330 lbs front/400 rear. We talked about my two different square tire selections, size, models, and car usage and he felt the springs would work very well. In a nutshell. no charge to change spring weights. I meant to ask him about a wider track and perhaps just staying with the 400/457 springs but that will be another discussion.

I've got the Ohlins on my Cayman and have about 10,000 miles on them and maybe 9 HPDE events, I love them and so has everyone that has ridden with me. I've never experienced any "higher spec track only" coilovers but for a dual.purpose hpde/weekend cruiser, I think they are great. When they wear out, and if I start trailering the car, I'll get them upgraded to a track only spec.

Thanks, looks like Ohlins is the way to go for me. I also spoke with Ohlins in North Carolina and they convinced me not to drop the spring rate and that I will be very happy with the 400/457 springs. Brian at Ohlins said to go as far as a 15 to 20 mm drop, possibly more but to be careful as there can be rear axle contact. That will be plenty and gives me maneuverability with my initial tires, which will also drop the chassis 1/2". I'm thinking initially to try a safe 100mm chassis to ground setting plus -13mm from the tires. About ready to start a build thread.

I recently ordered the ohlins R&T "track package", which changes the valving to match my selected springs of 450/550.

If you haven't ordered yet, I highly recommend Josh at arcflash. If you need contact info, lemme know.

Sent from my SM-G970U using Tapatalk

I won't be ordering for quite a while but sure. Thanks, I'll give him a shout.

I went with the minimum drop - which on mine turned out to be 18mm. Another reason why I went with the Ohlins - and the fact that height and spring pre load are separate adjustments. The 400/457 are fine on the street.