Welcome to “Ask Phill,” the creatively named column where I answer your automotive questions, despite being totally under-qualified to do so.
Today’s question comes from Roman:
“I've always wondered, does oversteer (to a certain degree) in a front-wheel drive(FWD) result in better lap times?”
Alright Roman, let’s get one thing out of the way: oversteer in any car in any situation, on a racetrack, will not result in faster lap times. If you’re sliding, you’re scrubbing off speed and losing precious seconds.
Disclaimer: This was written with autocross/track days in mind - I've seen fwd rally cars use oversteer to carry momentum and rotate around hair pins, though I can't adequately explain how.
But, I get what you’re saying. A lot of people will setup their cars to be more oversteer baised. There’re loads of ways to do this:
- Stiffer rear springs
- Stiffer rear shock valving
- Softer front springs
- Softer front valving
- Thicker rear sway bars
- Thinner front sway bars
- Alignment settings, etc.
People do this not to induce tire-smoke producing oversteer, but to reduce understeer and allow the car to rotate. FWD cars are prone to understeer for a number of reasons, and intentionally so: oversteer in a FWD car tends to lead to the dangerous and terrifying phenomenon known as snap-oversteer.
Imagine you’re diving into a right hand turn and the car begins to wildly oversteer. The front tires are counter steering, while the back tires are sliding and creating JDM-tire smoke. To recover from the drift, the back tires need to go from sliding, to gripping smoothly. Rear-wheel drive (RWD) cars can manage this by staying on the gas to spin the back tires, allowing them to slowly regain grip. FWD cars can’t do this.
The rear tires of an oversteering FWD car will begin gripping very suddenly. As the car is oversteering, its weight is being thrown to the outside of the corner (i.e. body roll). Now the rear of the car has stopped sliding abruptly, as if your outside wheel smacked a curb. All that weight that was rolling to the outside of the turn is sent ricocheting back towards the inside of the turn, taking the car with it. RWD cars can do the same thing obviously, if you immediately let off the gas mid-drift (hence the phrase – don’t lift off). A front-wheel drive car can avoid it by mashing the gas and praying that power to the front will pull you out of the drift, but if you haven’t got massive power, good luck.
Here's a video of me snap-oversteering really, really badly at TMP Cayuga in my 06' Civic.
The moral of the story: you really don’t want oversteer in a FWD car. Modifying a FWD car to make it more oversteer biased can reduce understeer and help it rotate, but actually causing a FWD car to oversteer is a bad idea.