Changing brake bias during a race

[BhZ]

I was watching some onboard videos and noticed that sometimes the driver change the brake bias during the race. Can anyone explain why i should change it?

 

[Stereo]

Same reason you'd change it for a setup in general - forward brake bias = more understeer when braking, rearward brake bias = less understeer.


It changes over the course of a race because you're burning fuel (changes weight distribution, in lots of cars) or wearing out the tires unevenly.

 

[BhZ]

Ok but i noticed that drivers sometimes change it twice a lap. Does that depend on the turn? i thought that maybe depends on the weight transfer and the inclination of the track during a turn.

 

[Fernando Deutsch]

Nowadays on some series is common to see drivers changing it, and as you said it depends on the turn, not the same doing a threshold braking or a trail braking, both require a different brake bias in order to be optimal.

 

[BhZ]

So, to make an example: if the road goes down the front of the car will be heavier and the rear lighter, it may be usefull to increase the front, am i right?

 

[ouvert]

usually after long straight before heavy braking into slow corner you move you BB more towards front. Than you change it back for 'normal' braking

 

[Fernando Deutsch]

Is more as @ouvert explain @BhZ . On threshold hard braking you will move brake balance to the front to optimize the front grip due to the front weight transfer. On trailbraking you have to reduce brake power at the front in order to provide the front tires with grip to still do some cornering.

 

[ouvert]

yep .. hard braking -> more weight on front - if you have brake bias too much on rear that is now lighter, rear tyres will lock more easily (less weight means less power needed to stop it) -> rear will loose traction -> oversteer

That is considering you have good suspension setup and by changing brake bias you are only adapting to that pecific hard braking corner ... it is not good cure to oversteer in general


One way how to set it up is to brake hard and than on replays (or my preference in MoTec) watch which tyres are locking first .. if rear you should consider moving bias more to the front for that corner

 

[BhZ]

The topic seems clear but tbh it doesn't seem easy to apply when racing. i'll make some tries hoping to succed.

 

[ouvert]

The topic seems clear but tbh it doesn't seem easy to apply when racing. i'll make some tries hoping to succed.

What do you mean? what seems to be hard ? when to do that or doing that while focusing on driving?

Map it to your wheel or button box - you don`t wanna search for bracket keys on you keyboard while racing I used to have it on rotary button but switched back to +/- buttons on wheel

Than if you are driving at high speed (highest gear or high speed in general) and you know you gonna brake to 2nd or 1st gear you probably wanna move it few clicks to the front (as it happens after long straight you have enough time to do so), than you go same amount of click back to rear.

Would be nice to have 2 predefined values and just switch between them but you`ll get used to it easily, not really thinking about it

 

[BhZ]

What do you mean? what seems to be hard ? when to do that or doing that while focusing on driving?

Map it to your wheel or button box - you don`t wanna search for bracket keys on you keyboard while racing I used to have it on rotary button but switched back to +/- buttons on wheel

Than if you are driving at high speed (highest gear or high speed in general) and you know you gonna brake to 2nd or 1st gear you probably wanna move it few clicks to the front (as it happens after long straight you have enough time to do so), than you go same amount of click back to rear.

Would be nice to have 2 predefined values and just switch between them but you`ll get used to it easily, not really thinking about it

At first someone said me that i had to move the brake bias to the rear as long as the rear doesn't lock before than the front. Should i start from there and then move to the front when i have to brake hard?

 

[ouvert]

sure .. you probably wanna have neutral, stable car under normal braking ... yes, you don`t wanna rear to lock first as locked front is safer (just understeer rather than snap oversteer on rear).
Unless you are aiming for oversteering ..
Also using ABS in cars that support that is not lame, it is smart

 

[BhZ]

sure .. you probably wanna have neutral, stable car under normal braking ... yes, you don`t wanna rear to lock first as locked front is safer (just understeer rather than snap oversteer on rear).
Unless you are aiming for oversteering ..
Also using ABS in cars that support that is not lame, it is smart

Yeah i mostly use the gt3 so abs always active and i'm trying to understand the behaviour of those cars when changing a specific aspect in the setup.
Speaking about suspensions, what is the general rule? I mean, when should i prefer soft over rigid and viceversa? I know that they can change the behaviour of the car talking about oversteer and understeer.