Unstable Braking .. Why ??

Currently doing BMW E30 Grp A@Monza, the car always go right under heavy braking after the 1st right left turn (chicane ?), not understand why it happen.
Thanks for the concern.

 

This car has no ABS, you are slamming on the brakes so wheels are locking. Try to be more gentle with the brake pedal.

 

Then why it not happen on the 1st chicane ?? Thats what i dont understand cause i brake the same way

 

Maybe the surface is not the same , maybe a 0.05 degree sloped on the left or on the right and the tyres have not the same grip on the tarmac.

 

Try a higher brake bias. Currently on 66, try 75.

From the vids, your rears are locking up before the fronts.

 

Also, they need to develope some heat in them as when cold will react adversely.

 

All I see is that you brake at 100% and lock the wheels, and you don't even lift your foot a bit to stop it, but maybe that was to emphasize your point.
In any case, if you keep the wheels locked like that, it can only go pear shaped, right or left.

 

Your problem is your brake input. There is a slight slope, so car the car is generally more unstable under braking there. Don't let more than 1 wheel lock up at any time for more than a split second. You'll brake sooner if you do that as you keep the wheels rolling instead of scrubbing the asphalt. Take care and work on your footwork!

 

I gave it a try and can confirm that the car will go right if you lock the wheels at this place whatever the setup.

As others said the solution is a better footwork on the brake pedal. Changing the brake bias will not help improving things, the car will just feel less unstable when you lock. In addition, moving the brake bias to the front will increase your braking distance on the M3.

 

As much I agree on importance of proper braking technique, 66 balance is a little too much. It's really obvious during braking into T1 that even without downshifting the car is limited in grip on the rears.
I personally used the default 69 for great results, and i believe around ~68 gives the best braking force.

@OP If you are lacking turn in power with higher brake balance (during trail-braking), instead of moving the brake balance so far backward, try shifting down earlier when going into the turn, decrease front toe (by a lot, to something like -0,15 or even above -0,2), lower coast diff power or just try smoother weight transition (avoiding front inside lockup while keeping the front wheels loaded with good amount of braking).

 

i've noticed the braking instability is more substantial now. devs may have bumped that feature up. it's quite noticeable around the Nurburgring.

 

iRacing had an issue with road camber at one point which produced the same results. The car would want to veer away from the road crown (down the slope) under heavy/locked braking. Makes me wonder if Kunos have made a similar mistake in the physics.

 

Tracks are laser scanned so no mistakes there, Darren.

@Nao - While I agree on the rest you'd stated, diff power change won't help during braking as the diff is lock in the opposite direction - coast, as the pre load diff is locked at this car, power setting alone won't come into play until you get on the power. At least that's my understanding.

 

Ah good catch, can't edit that now thou .
By "power" i meant strength, as in "coast differential lock strength".

 

Thanks for all the tips though i actually not understand those coast or diff power thing; Yeah no such problem using 68/69 brake bias but car a little bit hard to turn in with trail braking .. in the 1st 2 chicane. I lost alot of time there thats why i try to lesser the brake bias.

 

If you look at your temps and pressures before applying brakes there the left side is quite a bit warmer then the right also higher pressure on the left for the same reason. Left side will have more grip and so will likely lock before the right side causing the car to go right here as you dont have even traction at each corner. Seeing as there is a high load sweeping right hander before this chicane so the left side will generally always have a temp and pressure difference.

Braking the way you are is never going to work either so avoid locking up as much as possible, some corners its quite tricky the avoid locking the inside front tyre as its the least loaded but if your getting into a complete lock you have no control. Even if it didnt go right you would end up going straight on and as soon as you notice locking wheels you should release pressure and use less the next time around.

 

Try the toe out on front wheels then. Something like a setting of "10" should do the trick.

 

By the way one question about this brake bias thing .. i found many people recommend to use 21 steps setup Guide to tune the car and now lets see what step 4 is about :->

So is this really the way ?? The reason why i keep on to lower the brake bias to rear is because i found my front whee lock first .. but @Nao (Current WR holder in this combo) say actually he is using 69 ??
I must say many of thses setup guides are very very confusing, at least to me

Yeah i do realize all you say about front left right tyre's temp & psi different but i have no idea at all how to make my right tyre warmer (-2psi for right tyre or increase bump didnt work). Also i understand what you say about braking too, i actually not asking why my car unstable like that but i am asking why it unstable in 2nd chicane but not 1st chicane (top speed area), but i guess i know the reason now thanks to previous comments.
Thanks again for all the tips and better if any idea to make my right tyre warmer .. i fail to find a way to achieve that .. may be i should increase the negative camber for this tyre ??

To be honest i do try extreme toe-in & toe-out but no different ... may be its because my braking is too bad ... i think i should improve that first. I hardly do more than 2 laps without crashing atm (Especially on the 2nd chicane, either crash or get penalties)

Its good Codemaster announce new Grid: Autosport, so i can play that game to relax a bit every time i feel too frustrated playing this game.

 

By the way, you can safely cut the entry of the 2nd chicane without being shown the 5sec penalty or RSR app turning red. Just avoid the grass and bump stone.