Coil over spring rates

[Topless]

This thread has a lot of discussion about various spring rates and their effect.
m030 spring rates

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

[Hasbro]

Originally Posted by Topless

This thread has a lot of discussion about various spring rates and their effect.
m030 spring rates

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.

[Topless]

Originally Posted by Hasbro

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.

[thstone]

Originally Posted by Topless

... 270F/370R and it was *just enough* spring to reduce roll and make quicker transitions while still having full grip on corner exit.

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.

[Hasbro]

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?

[Topless]

Originally Posted by Hasbro

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?

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.

[rastta]

Originally Posted by Topless

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.

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.

[steved0x]

Originally Posted by rastta

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.

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.

[Hasbro]

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.

[Topless]

Originally Posted by rastta

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.

I appreciate the tip on Ohlin RTs Rastta. I was pretty disappointed with PSS9 on my Boxster and wanted to steer clear of Bilstein but JRZ is just too precious $$ for my planned use. At $2900/set this is a reasonable coilover with good reviews for dual sport use. My other option is a Cayman R "kit" for $2400. I have enough laps in cars with these to know they are pretty good street and track but the RT adds ride height adjustability. A worthy contender.

[thstone]

Originally Posted by Hasbro

Topless, thstone, either of you run a square setup?

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.

Originally Posted by Hasbro

Aren't the PSS9s going the way of the Dodo bird?

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

Read about it here: PCA Announces New Spec Boxster Shock Package