| Author | Message | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 287 Registered: 11-2002 |
RobL, Your autocross BMW Koni settings: sound like you're trying to combat tail happiness. Generally, full stiff front rebound and full soft rear rebound tells me you have corner entry oversteer and you're trying to get the rear to hook up quicker/better and simultaneously slow weight transfer up front so the front waits for the rear to hook up. Sound right? I know that many BMW's tend toward oversteer, though typically at higher speed corners, not necessarily auto-x speeds. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 283 Registered: 11-2002 |
I am available for consultation in person for testing/ race events, or via telephone / email. Affordable, too. | ||
| Rob Lay (Rob328gts)
Board Administrator Username: Rob328gts Post Number: 3742 Registered: 12-2000 |
Man I wish I knew what you knew Rob. Man I wish I could just understand what you're talking about. My race car set up experience consists of... Car pushes vs. being "nervous" (Understeer vs. Oversteer). I also realize you want the car to be overall faster, which may mean sacrificing speed on one turn to get more speed on three others. Only things I have to mess with on the Spec. RX7 are tire pressures and I'm allowed to remove the rear sway bar. On my BMW autocross car I have adjustable Koni's that I have set to full loose in the rear and will go full tight in front. I have a few Carol Smith books, just haven't had a chance to read them. He has a little quick reference key which sums up about everything though. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 280 Registered: 11-2002 |
Actually, if one wants to "tune" the chassis for improved lap times, I would not suggest increasing rear wheel rate to keep it off the stops. The risk is upsetting roll couple distribution for cornering power. Every adjustment changes the entire system, therefore it is the best compromise to improve what is most important (high speed corners) and sacrifice what is less important (low speed corners). It is always "system tuning". I wish I could separate individual dynamic characteristics so easily. BTW, this is why F1 and other top forms of motorsport utilize "third spring" suspension. It effectively separates pitch and heave from roll. This is critical in down force producing chassis, and desirable in all vehicles. As a dynamicist, one's goal is heave and pitch stiff, roll somewhat stiff, and warp mode very soft to accommodate road imperfections and improve mechanical grip, therefore traction coming into and exiting corners. | ||
| Hubert Otlik (Hugh)
Member Username: Hugh Post Number: 563 Registered: 1-2002 |
Rob- I'm going to disclaim my comments by saying I'm recounting from memory. However, I know that the springs, in the rear were changed; in the example you list, however, you'd want a stiffer spring rate (not softer as I noted) to keep the car off the bump stops. Maybe Tim will chime in. Apologies if I've lead anyone in error. -hubert | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 277 Registered: 11-2002 |
As far as race cars go, the 360 Challenge is very soft. Hubert, what you may be refering to, IME, is the ride height sensitivity of the rear suspension, and the chassis in general, due to ground effects. The car generates enough downforce that if one runs the rear too low, above 100 mph the chassis will pitch up and down in the rear first as the rear is "sucked" down, then hits the bump rubbers hard, then reacts upwards, then repeats the process. It is important to keep the rear off the bump stops but still low enough to take advantage of the aero grip. | ||
| Kenny Herman (Kennyh)
Member Username: Kennyh Post Number: 605 Registered: 8-2001 |
Steve, make sure it has a passenger seat  . | ||
| Hubert Otlik (Hugh)
Member Username: Hugh Post Number: 561 Registered: 1-2002 |
Steven- Email Tim G. he has some experience in setting up a 360 c, he was also selling his 360c a while ago. The car you're reffering to 'may' have 360-GT cams, or a different ecu, or pistons; all components that were changed on the 360 GT car. From what I remember the 360c are very stiffly sprung, especially out back, going to softer springs, seems to tame the back end a little. | ||
| Ernesto (T88power)
Intermediate Member Username: T88power Post Number: 1269 Registered: 2-2001 |
Buy it Solly! You have to promise to give me a ride in it! And of course I'll give you a ride in the helicopter... Anyway, try to find out what the mods are... Ernesto | ||
| Steven J. Solomon (Solly)
Member Username: Solly Post Number: 451 Registered: 6-2001 |
The wonderful people at Shelton have found me a fairly unmolested 360 Challenge-going to see it this Friday. They told me it is not legal for the Challenge series (which I don't plan on doing anyway)due to a very modified motor putting out more than Challenge-legal bhp. Anyone hear of this type of modification? anything I should know before I take my life in my hands? |