Q: I’m really having trouble understanding what slip angle is and how it works. Is it something you should feel? Is it like or does it feel like oversteer? How do I know what slip angle I’m at? How does it affect my lap time? And most importantly, how to do it?
A: First, it doesn’t matter what the slip angle really is, in numbers. The important thing to know is that with a little bit of slip, the tires actually generate more grip/traction. That’s why the car is sliding just a little bit when we’re driving at the limit, as fast as we can go around a corner.
If the slip angle is greater on the rear tires, that is oversteer – they are sliding more than the front tires are (think of a drift driver – that is extreme oversteer, and an extreme amount of slip angle on the rear tires, much more than the front tires have). If you go into a corner, turn the steering wheel, and the car kind of plows straight ahead – or just doesn’t turn as much as you wanted – that’s understeer. In that case, the front tires have a higher slip angle than the rear tires.
Ultimately, slip angle is just a way of measuring or quantifying the amount the tires are sliding. Too much sliding (slip angle), and you are losing grip (again, the extreme demonstration of this is the oversteer of a drift driver); too little slip angle and you’re not using all the available grip that the tire has to offer.
Do you feel it? Yes, if you’re driving the car fast enough to get close to the limits of the tires. If you’re driving at street legal speeds, you shouldn’t ever feel it because there is almost no slip angle. If the car is sliding a lot, you will feel it, and in some cases you’ll feel that the front or rear tires have more slip angle than the other end of the car does – you feel the understeer or oversteer, typically in the steering.
Again, as a driver, you don’t care if the slip angle is 5.65% or 15.2% or 3.4% of 9.6% or… You don’t care about the numbers. Your job when trying to drive the limit is to sense which end of the car (the front tires or the rear tires) have the most slip angle, and manage that. Actually, before that even, your job is to ensure there is some slip angle – some sliding – but not too much.
In my Performance Driving Illustrated eBook (it’s free to download at SpeedSecrets.com/eBooks), I have a illustrations about slip angle that might help you understand it better.