Contour Enthusiasts Group Archives Forums General Autocross and Open Track Under vs. Oversteer

Understeer is preferable in slaloms and S-turns where a turn in one direction is immediately followed by a turn in the opposite direction. Understeer makes any car more stable at high speeds. Understeer is preferable to oversteer if you have too much rear-brake bias, and you are entering a turn! Understeer is preferable if you are a NASCAR driver and some idiot is going to bump you in the rear as you enter the turn.

Impressive answers by one and all. Those schools paid off MFE. Who is Jeb? New guy or new name?

At high speeds (over 100 mph) you want the steady state balance of a vehicle to be slightly understeering. Not driver on the planet (including Shuie) can drive a steady state oversteering car at high speeds - for very long. Most race vehicles use aero to achieve balance at speeds in excess of 100 mph.

Since autocross is a low speed event and is mainly composed of transitions, you want the car balanced more towards oversteer. On a FWD car you go to extremes to achieve this:

1. 1/4" to 1/2" toe out in front.
2. 0 to 1/4" toe out in rear.
3. Move roll stiffness to the rear.
4. Extreme air pressure differences front to rear.
5. Rear brake bias.

If you ran these specs while on a race track the car would probably be undriveable at anything over 70 mph.

Some road racing friends gave me this humorous definition several years ago...

Understeer: When the driver is scared.
Oversteer: When the passenger is scared.

One problem with oversteer, I actually hit a cone with my left rear while in a right hander. WHAT A BLAST!!!!

John

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johnc wrote:

Since autocross is a low speed event and is mainly composed of transitions, you want the car balanced more towards oversteer.
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Just make sure you are aware he's talking about Solo II (parking lot) autocross. (which is why he mentioned the uncontrollibility over 70mph) Solo I (highspeed) racing you ideally want it balanced in fast turns so you have the option of some over or understeer.

And be careful with 'extreme' pressure differences front to rear. You don't want to blow a tire (too much pressure) or ruin a rim (too little pressure).

Ah, the nuances of racing. Gotta love it.

I'm not sure I agree.. I think it's a bit more like this

Understeer: when the driver (me) is cursing loudly and the passenger is smiling

Oversteer: When the driver (me) is laughing maniacally and the passenger is wondering why he suddenly needs diapers.

Just my take on the issue

'laughing maniacally'...THATS ME!!

I'll have to second this opinion on the best explanation.