legacycentral bbs

So, a friend of mine has GC Coilover sleeves, and they have a little number on them, 400 and 500. I was thinkin about taking them off his hands.

I'm pretty sure that is the spring rate, how stiff will that be? Totally unbearble?

I'd imagine it will handle insanely but still, that seems hella stiff. With AGXs would that be bouncy?

bump?

Been doing some reading.

Even though all the mad tyte JDM track coilovers run retarded rates in the 600lb/in range, I can't find much information that says anything very far above 400lb/in is really necessary or will be beneficial. When the springs or struts are too stiff, traction actually decreases. Partly because it's harder for the tire to maintain contact with the road, partly because the chassis is bouncing around all over the place, and partly because the tire gets overloaded and over heats.

If I was hardcore into tracking the car I think I would go with 400/350 or so rates and 22mm front and rear bars, even on R-compounds. It might be on the low end of the required roll stiffness for that kind of grip, though.

I'm not hardcore about tracking the car, and wouldn't actually ever go that stiff I don't think. Even with my sti suspension, which has 224/194 rates, I'd probably be better off just adding swaybar. That gives me more travel and is probably better for the type of driving I do, which is on real roads. According to some calcs I've found on nasioc, a stock sti will only have about four degrees of body roll at 1.2g lateral acceleration. Bump up the swaybars to 22 or 24mm, add negative camber, and you don't need much more roll stiffness, if any at all. You really want the car to be as soft as possible while maintaining acceptable amounts of camber. Having the car softer means the suspension uses more travel and follows the road better. It also loads the tires more gradually while turning and braking. That means more grip.

I suppose if I were to do a sleeve setup I would keep things around 300lb/in or so. It's actually about the softest you can go with a linear spring on our cars without having problems with droop travel or coilbind (where the spring bottoms out). At those rates you also need lengths of 8" up front minimum, and 9" or 10 if they'll fit or are available (not sure on that). I think you want 10" rear springs, but it would be best to check with the guys at ground control.

There still are some possible benefits to higher rates, such as reduced dive and roll, and the ability to lower the car more, less risk of coilbind, but I don't think they're useful off a track.

I'll second that. Too stiff might be OK on a perfectly surfaced track (not Sebring, for instance), but will not only be a bear to tolerate on the street but will be more likely to send you into a Jersey barrier than too soft if you encounter any kind of bad pavement mid corner. If you've driven a car with a live axle fast through a bumpy turn, you'll have something of an idea.

Interesting didn't know you could specifiy spring length as well as stiffness with the GC folks. Is that true? Tell me more. I'm planning to order from them later this year and the above thinking is very helpful...