By Stefano Casillo - Kunos Simulazioni on Iracing forum
"Interesting thread, the good old hit the brakes to save a spin debate :P
Some thoughts about the issure;
I hope you all realize that the car will align itself to have the side with less grip "forward", ie, in the direction of travel. 2 simple way to prove it: get a pen a throw it on the floor, it'll rotate in a pretty random fashion. Now stick a rubber to one side of the pen and repeate; the pen will always stop rotating straight away, align to the direction of travel with the rubber end BEHIND. The hard way to test this is to get in a parking lot, get some speed, hands off the steering wheel, pull the hand brake and woooosh, ur rear end will end up where your nose was pointing. Simple reason is that the rear tyres locked up loosing much of their directional grip. I hope we all agree about this.
So let's apply the hand brake thing in reverse, to our front tyres, if they lock up first what is it going to happen? Racing school will teach you that the car "won't turn with locked front tyres".. that is right, but it is only part of the story, actually, locked front tyres will align the car into the direction of travel; that is a more complete description.
So if you manage to lock your front without locking your rears you will save pretty much every slide, even a 180 degress slide (remember the car reaction with the hand brake? it swapped ends).
On to the sims now... how come it is so easy to get into this situation of locked fronts and unlocked rears in the sims? Let's see some of the reasons:
- Brake pedal resolution. In real life, brakes work with pressure and the limit is strength you have in ur foot. In a sim, the brake pressure is determined by a pedal position, with a definite minimum and maximum. The maximum is often set to maximise the control and usage of the brake pedal in normal situations. If a real car has a potential braking torque of X but this (as it often is the case) overpower the tyres potential grip the sim is often set to have the maximum a little above the tyre limit. This avoids having that terrible feeling of locking tyres as soon you touch the brake. It is often the case that this value is not enough to lock the rear tyres (more rotational inertia, more grip and all that stuff) so you get that behaviour you condemn. In real life this would be probably a "PANIC" manouver, just hit the brake as hard as you get.. but there is no "maximum" in real life, so it would be impossible to reproduce it in a constant way as in the sims. In RL you'll have to find the right pressure needed to lock the fronts and not the rears.. and consistently repeat this in a PANIC situation. Still asking yourself why nobody really bothers teaching this stuff? In RL you fix it the right way (tm): you avoid the spin in the first place
- Setup. If we get a 100% front brake bias, we'll be able to save pretty much every slide. Is it cheating? No, it's just stupid! it means we're giving up optimal brake distribution (thus, lap times) to save our asses when we make a mistake. No driver nor engineer in with a sane brain would even think about this.
- Finally, potential software bugs. It happens, I've been there all my life . It's important to make sure a rear tyre at high slip angles will lock instantly even with very low braking torque. But heavy front biased braking and gas on will still save the slide if the brake pedal maximum is set too low.
Want to prove all these things right? Get in your favourite sim and set the brake gain as high as you can ( you should be able to lock tyres with 20% brake pressure) then slide, brake hard and watch the car completing the spin slowly coming to a stop , just as we see on TV.
Sorry for the rant.. I love this topic :P"