Source
r/simracing•
d95err

Throttle and brake at the same time?

Question

I notice in when I get access to other peoples sim racing setups, they often have brake bias set very far back, to the point where the car more or less spinn automatically under breaking, unless you also apply a bit of throttle at the same time. I used this technique myself back in the old Grand Prix legends days and I know it can be used to get more effective braking. However, it also requires extreme concentration and attention in the braking zones.

My question is - is this a pure "gaming"-technique, or do real-world drivers set brake bias like this too, having to use throttle to balance the car in every braking zone?

Can real cars actually handle using a lot of brake and throttle at the same time, or would it cause mechanical failures, overheating or excessive wear?

Intuitively, I'd guess that using throttle and brake at the same time would usually be avoided in real cars. I also don't think real-life drivers wouldn't want cars that try to kill them everytime they hit the brakes, unless they apply a bit of throttle.

Posted Jun 18, 2020, 12:55 PM UTC

127
FiveWheelRick•

It works in real life but I think it's very hard on the diffs. I remember when pastrana was rallying the mechanics were really annoyed that he was doing this to keep the car straight under braking.

What happens is under throttle the diff starts locking and keeps the rear tires from rotating at different speeds. So if you just brake and one of the rear tires bite more (due to weight imbalance when not braking super ruler straight) it's going to be hard to control the car. However if you lock the diff with the throttle this doesn't happen. But in real life if one rear tire is biting more than the other with the diff locked, all that stress is going to be shouldered by the diff.

GPL was awesome but the competitive scene was based around these insane asymmetrical setups that nobody in their right mind would run.

9
d95errOP•

Thanks! Very good explanation!

I remember trying Greger Huttu’s GPL setups back in the day. I was fairly decent at GPL but couldn’t make it two corners with his setuos. He was really from another world...

2
FiveWheelRick•

I think he used a joystick for a while. I did too and there's an advantage being able to go lock to lock 5 times a second, and also just tracing out a traction circle with your hand.

That said I'm glad iracing has tighter setup limits so we don't get subjected to that granite suspension pain anymore.

2
MrBfJohnCSL Elite & Quest•

I have mine set much more to the rear than the stock Assetto setting in RWD cars as I find the stock setting just locks the fronts up with even the slightest pressure. I was previously reducing my braking power to compensate for this, but with altered bias I get better braking and less lock ups. The trick is to get it to the point where the rear isn’t locking up, but does have some life in it whilst trail braking.

2
d95errOP•

What I’m talking about is using very extreme rear bias, where the rears lock long before the fronts. The car will spinn immediately unless you use a bit of throttle during braking to dynamically shift brake bias forward.

I know some very fast sim drivers use this technique. Just wondering if this is used in real-life racing, or if it’s only a simracing technique.

4
[deleted]•

[deleted]

2
II-WalkerGer-IITM TX | Rift | AC(C), AMS, Dirt, iRacing•

Of course you can do it in real life, but it's not good for the car. As the other guy said the diffs don't like it, but neither does your engine. So what I would suggest is to set the brake bias just in front of that point where you would need throttle to keep the car stable. Then you won't need throttle but the car is still rotating nicely

2
d95errOP•

Thanks!

That’s kind of what I thought. So while possible in real life, the reason we can do it in sims is that they are usually limited in the modelling of mechanical stress and wear on components

2