Under/Over Steer
Thread Starter
Le Mans Master
Joined: Jan 2001
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From: Lafayette Colorado
Under/Over Steer
How bad would the under/over steer be with the 255/40/17s up front with 345/30/18s in the rear? Also a 255/40/17 should fit on 17x8.5 rim right? TIA.
Keith
Keith
Le Mans Master
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From: Hot Springs AR
1. HUGE understeer
2. Yes, 255s will fit on stock front wheels.
The C5s understeer with a 245/275 f/r split. Adding 70mm to the rears without going to at least a 275 up front (which will also work nicely on 8.5 rims) will make the situation much worse.
I'm changing over to a 275/315 split for autocross, but haven't had a chance to try it yet. I'm expecting a small amount of understeer, but hopefully will cure my oversteering problem (currently running 275s all around).
HTH, and have a good one,
Mike
2. Yes, 255s will fit on stock front wheels.
The C5s understeer with a 245/275 f/r split. Adding 70mm to the rears without going to at least a 275 up front (which will also work nicely on 8.5 rims) will make the situation much worse.
I'm changing over to a 275/315 split for autocross, but haven't had a chance to try it yet. I'm expecting a small amount of understeer, but hopefully will cure my oversteering problem (currently running 275s all around).
HTH, and have a good one,
Mike
Last edited by VetteDrmr; Sep 23, 2004 at 03:22 PM. Reason: didn't see the "over" part of the question
Drifting
Joined: Jul 2000
Posts: 1,517
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From: Stockholm
Originally Posted by kromberg
How bad would the under/over steer be with the 255/40/17s up front with 345/30/18s in the rear? Also a 255/40/17 should fit on 17x8.5 rim right? TIA.
Keith
Keith
Last edited by vette.se; Sep 23, 2004 at 03:31 PM.
Melting Slicks
Joined: Jul 2004
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From: Edmond, OK...One of the first rules of online forums: If you don't like what is said but can't refute it, attack the poster.
I always get understeer and oversteer mixed up. Can someone tell me what each is?
Thanks,
Jeff
Thanks,
Jeff
Le Mans Master
Joined: Dec 2003
Posts: 5,561
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From: Atlanta metro Ga.
Originally Posted by JeffC5
I always get understeer and oversteer mixed up. Can someone tell me what each is?
Thanks,
Jeff
Thanks,
Jeff
Oversteer= rear end "comes around" at the limit.
Le Mans Master
Joined: Dec 2000
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From: Hot Springs AR
Originally Posted by kromberg
I guess another thing is that I do not road race or autocross the car. The main convern with this combo would be 'normal' city street and highway driving.
Keith
Keith
Now, with 345s out back, you probably won't have much problem with power oversteer, except in a tight corner (like an intersection).
Curious, why are you running such huge tires on the rears?
Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 5,786
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From: Lafayette Colorado
Originally Posted by VetteDrmr
Curious, why are you running such huge tires on the rears?
Keith
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Drifting
Joined: Apr 2003
Posts: 1,764
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From: Fort Collins CO
Originally Posted by VetteDrmr
I'm changing over to a 275/315 split for autocross, but haven't had a chance to try it yet. I'm expecting a small amount of understeer, but hopefully will cure my oversteering problem (currently running 275s all around).
(big smiles!)Perhaps you need to adjust your rear toe (1/8" in works well), rear camber (more is better up to around 1.5 or 1.6*), too much rake (try lowering the back of the car a bit), too much rear rebound in the shocks (try softening the rear rebound), or, perish the thought
, an overly ambitious right foot? Is it corner entry oversteer, corner exit, mid-corner, or transitions/slaloms?Keith - just puttering around on the street, I'm sure understeer won't be a problem - it's tough (not to mention irresponsbile) to push a C5 hard enough on the street that you approach its limits.
Advice worth the electrons used to make it,
-Jake
Last edited by JakeL; Sep 23, 2004 at 04:48 PM.
Team Owner
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From: Overwhelmed as one would be, placed in my position.... DFW, TX
St. Jude Donor '05
I think your traction problems far outweigh any oversteer/understeer concerns you will have. You're gonna be makign huge power and need the big rear tires. I would look into running 275's on the front if you can.
Additionally, you can adjust the balance of the car with suspension changes. Go to a stiffer rear bar, for example.
Additionally, you can adjust the balance of the car with suspension changes. Go to a stiffer rear bar, for example.
I love that little gold nugget of wisdom.
Le Mans Master
Joined: Dec 2000
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From: Hot Springs AR
Originally Posted by kromberg
Just about to fire the new combo up: 402 Stroker with a F-1R Procharger. I also have 3.90:1 gears and 3800 stall converter. I am hoping the 345 DR will give some type of traction
Keith
Keith
Have a good one,
Mike
Le Mans Master
Joined: Dec 2000
Posts: 9,899
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From: Hot Springs AR
Originally Posted by JakeL
Perhaps you need to adjust your rear toe (1/8" in works well), rear camber (more is better up to around 1.5 or 1.6*), too much rake (try lowering the back of the car a bit), too much rear rebound in the shocks (try softening the rear rebound), or, perish the thought , an overly ambitious right foot? Is it corner entry oversteer, corner exit, mid-corner, or transitions/slaloms?
-Jake
, an overly ambitious right foot? Is it corner entry oversteer, corner exit, mid-corner, or transitions/slaloms?-Jake
I might have a bit too much rake, and it wouldn't hurt to get an alignment. Shocks are stock Z51, about a year old.
Any other ideas?
Sorry for the thread hijack, but hopefully it'll help others.
Have a good one,
Mike
