Managing oversteer - driver or setup?
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Joined: Feb 2001
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From: You wish
Couple of quick comments:
1. I run RA-1's all the time (street, track, etc.) in the same sizes as you (205/245). I have an 00, so my suspension is a bit different, but otherwise its totally stock. I don't auto-x the car, so my opinion is on track use only. Aside from the commentary about fresh tires (which I totally agree with - I was warned, but I didn't know they would be _that_ bad unshaved), have you considered changing your alignment and tire pressures?
Toyo tends to recommend tire pressures that are way too high for maximum grip (38-42 psi hot!!). On a vehicle like the S2000 (of middling weight) you can get away with running them sub 35 psi hot and the grip gets much better. Some guys I know with lightweight race cars (CRX's, etc.) will run them down in the high 20's hot!!
Alignment wise, because of the relatively soft sidewalls, the RA1's seem to like more camber. I run 1.75/2.5 on my car as a compromise street track setup. Were I going pure track I'd try to get more (some cars can't get much more rear camber). I believe Toyo says target 3-6 deg neg camber!!!
I have driven cars with big front bars and 205/245, and they understeer too much unless you go to a 225 front tire. With that combo the handling is positively wonderful (sometimes the 205 combo can pick up a little more understeer than I'd like).
Personally, I was pretty happy with my 205/245 combo until I drove a 225/245 Saner bar combo. Balance was about the same, but the latter had more grip with better turn in. But on my car, the handling is progressive rather than snappy on the throttle and allows me to put down power pretty well. When it does slide, it does so much more controllably than it did on the S02's.
2. On the topic of lift, the only 3rd party testing ever published was Sport Auto (german mag) which noted that the stock S2000 had 40 kg of rear lift at 200 km/h. Given that this was with the top up, I could imagine that it might get worse with the top down. The drag equation certainly changes, so lift probably does too. Given how aero effects work, that 88 lbs of lift at 120 mph would equate to about 22 lbs of lift at 60 mph, so clearly you'd notice it a lot more at speed.
UL
1. I run RA-1's all the time (street, track, etc.) in the same sizes as you (205/245). I have an 00, so my suspension is a bit different, but otherwise its totally stock. I don't auto-x the car, so my opinion is on track use only. Aside from the commentary about fresh tires (which I totally agree with - I was warned, but I didn't know they would be _that_ bad unshaved), have you considered changing your alignment and tire pressures?
Toyo tends to recommend tire pressures that are way too high for maximum grip (38-42 psi hot!!). On a vehicle like the S2000 (of middling weight) you can get away with running them sub 35 psi hot and the grip gets much better. Some guys I know with lightweight race cars (CRX's, etc.) will run them down in the high 20's hot!!
Alignment wise, because of the relatively soft sidewalls, the RA1's seem to like more camber. I run 1.75/2.5 on my car as a compromise street track setup. Were I going pure track I'd try to get more (some cars can't get much more rear camber). I believe Toyo says target 3-6 deg neg camber!!!
I have driven cars with big front bars and 205/245, and they understeer too much unless you go to a 225 front tire. With that combo the handling is positively wonderful (sometimes the 205 combo can pick up a little more understeer than I'd like).
Personally, I was pretty happy with my 205/245 combo until I drove a 225/245 Saner bar combo. Balance was about the same, but the latter had more grip with better turn in. But on my car, the handling is progressive rather than snappy on the throttle and allows me to put down power pretty well. When it does slide, it does so much more controllably than it did on the S02's.
2. On the topic of lift, the only 3rd party testing ever published was Sport Auto (german mag) which noted that the stock S2000 had 40 kg of rear lift at 200 km/h. Given that this was with the top up, I could imagine that it might get worse with the top down. The drag equation certainly changes, so lift probably does too. Given how aero effects work, that 88 lbs of lift at 120 mph would equate to about 22 lbs of lift at 60 mph, so clearly you'd notice it a lot more at speed.
UL
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Joined: Jan 2002
Posts: 15,835
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From: Vegas Baby, Vegas
Toyo recommends 2.5 to 5 degrees of neg camber for the RA-1s. With 1 deg/ 2 deg on my car, I definitely notice more outer wear so off to the alignment shop I go for more neg camber.
They do recommend what seems to be inordinately high hot pressures. I've been in the 35-37 range but am going to experiment with lower next time out. I'm running shaved 225/245 with a Saner bar btw...and love the grip. Nice and progressive, no hint of nastiness at all.
Thanks for the citation of the lift number. I've always wondered where that oft quoted measurement came from.
[QUOTE]Originally posted by ultimate lurker
Couple of quick comments:
1.
They do recommend what seems to be inordinately high hot pressures. I've been in the 35-37 range but am going to experiment with lower next time out. I'm running shaved 225/245 with a Saner bar btw...and love the grip. Nice and progressive, no hint of nastiness at all.
Thanks for the citation of the lift number. I've always wondered where that oft quoted measurement came from.
[QUOTE]Originally posted by ultimate lurker
Couple of quick comments:
1.
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