Randy Pobst on Over/Understeer and Car Setup
#16
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Originally Posted by 38D
For those that were at Daytona this past weekend, you may have seen Randy Pobst walking around. He was co-driving Jim Cipriano's 993tt in the enduro. While a group of folks was talking to Randy, he made a comment that most amateurs setup cars to oversteer too much. Pros tend to setup with a tiny bit of understeer as it is both safer and faster, mostly because it makes the car easier to drive. I had always thought pros liked a tiny bit of oversteer. Thoughts?
#17
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Forklift, here is a reasonable starting point to combat these states (not create them).
Entry Understeer - Increase the rebound of rear shocks. Decrease the bump of front shocks. Increase the rear brake bias. Brake earlier.
Entry Oversteer - Decrease the rebound of rear shocks. Increase the bump of front shocks. Decrease the rear brake bias.
Exit Understeer - Increase rebound of front shocks. Decrease bump of rear shocks. Stiffen rear springs/anti-roll bar. Soften front springs/anti-roll bar.
Exit Oversteer - Decrease rebound of front shocks. Increase bump of rear shocks. Soften rear springs/anti-roll bar. Stiffen front springs/anti-roll bar.
Entry Understeer - Increase the rebound of rear shocks. Decrease the bump of front shocks. Increase the rear brake bias. Brake earlier.
Entry Oversteer - Decrease the rebound of rear shocks. Increase the bump of front shocks. Decrease the rear brake bias.
Exit Understeer - Increase rebound of front shocks. Decrease bump of rear shocks. Stiffen rear springs/anti-roll bar. Soften front springs/anti-roll bar.
Exit Oversteer - Decrease rebound of front shocks. Increase bump of rear shocks. Soften rear springs/anti-roll bar. Stiffen front springs/anti-roll bar.
#18
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Slight oversteer on slow corners and (very) slight understeer on fast corners is what some pros (EDIT: and I) prefer. Reverse is the worst!
Last edited by Flying Finn; 10-19-2006 at 11:38 AM.
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I am not a pro but my personal preference is to have oversteer in the slow corners (helps rotation where cars naturally want to understeer) and have slight understeer at high speeds (lets me be more agressive in those corners).
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Originally Posted by SundayDriver
I am not a pro but my personal preference is to have oversteer in the slow corners (helps rotation where cars naturally want to understeer) and have slight understeer at high speeds (lets me be more agressive in those corners).
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Larry Herman
2016 Ford Transit Connect Titanium LWB
2018 Tesla Model 3 - Electricity can be fun!
Retired Club Racer & National PCA Instructor
Past Flames:
1994 RS America Club Racer
2004 GT3 Track Car
1984 911 Carrera Club Racer
1974 914/4 2.0 Track Car
CLICK HERE to see some of my ancient racing videos.
#22
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Colin,
First off, nice to see you again at Daytona. I started chatting with you then Randy and the synergy guy sauntered up and started chatting with us about this subject, so sorry if my attention drifted toward him!
I was one of those guys talking with Randy. He cleary stated that light understeer allows you to pitch the car in, then chase it with throtlle to balance the car on exit. I tried the sway bar settings he recommended to create this effect in the enduro and picked up a full 2 seconds a lap! The car was much easier to drive (GT3 Cup), and almost all the oversteer and tire spin in the back disappeared.
No, I am not a pro driver, but I will sure listen to one. What he said was spot on and the car control, lap times, and comfort factor proved him right at least for me.
Awesome fun at Daytona! Ya Hoo!
JL
First off, nice to see you again at Daytona. I started chatting with you then Randy and the synergy guy sauntered up and started chatting with us about this subject, so sorry if my attention drifted toward him!
I was one of those guys talking with Randy. He cleary stated that light understeer allows you to pitch the car in, then chase it with throtlle to balance the car on exit. I tried the sway bar settings he recommended to create this effect in the enduro and picked up a full 2 seconds a lap! The car was much easier to drive (GT3 Cup), and almost all the oversteer and tire spin in the back disappeared.
No, I am not a pro driver, but I will sure listen to one. What he said was spot on and the car control, lap times, and comfort factor proved him right at least for me.
Awesome fun at Daytona! Ya Hoo!
JL
#23
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JimmiLew, would you care to share the setup he recommended on your cup? I have a street GT3, but I would assume the swaybar setup would be similar.
I agree with the comments on slight oversteer in slow corners and slight understeer in fast corners, however, currently I have to temper that WOT application because I do tend to have oversteer on track out.
I have the front sway bar set around the middle, and the rear on full soft (running MPSC)--
Geoff.
I agree with the comments on slight oversteer in slow corners and slight understeer in fast corners, however, currently I have to temper that WOT application because I do tend to have oversteer on track out.
I have the front sway bar set around the middle, and the rear on full soft (running MPSC)--
Geoff.
#24
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i like a little over steer... that way through the stint if a little understeer comes in.. it will be ok...
if its set up for a lil understeer to begin with.. then it starts to understeer more through the life of the tires... then i got a problem...
if its set up for a lil understeer to begin with.. then it starts to understeer more through the life of the tires... then i got a problem...
#26
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Originally Posted by kingleh
i like a little over steer... that way through the stint if a little understeer comes in.. it will be ok...
if its set up for a lil understeer to begin with.. then it starts to understeer more through the life of the tires... then i got a problem...
if its set up for a lil understeer to begin with.. then it starts to understeer more through the life of the tires... then i got a problem...
Depends on what tires you are running, IMO.
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Originally Posted by kingleh
i like a little over steer... that way through the stint if a little understeer comes in.. it will be ok...
if its set up for a lil understeer to begin with.. then it starts to understeer more through the life of the tires... then i got a problem...
if its set up for a lil understeer to begin with.. then it starts to understeer more through the life of the tires... then i got a problem...
#28
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Originally Posted by Larry Herman
I would think that is more easily achieved in an aero car like yours. Set the mechanical grip for mild oversteer, and then add enough wing to keep the back in place at higher speeds, si or non?
#30
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Originally Posted by karlooz
....but if you start to overdrive your rears or when the rears begin to fade then you've got, instead of a little oversteer, you've got a lot of oversteer... no?
well then dont overdrive the rears...