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eracerhead
08-11-2017, 16:59
I'm slowly getting back into setup creation after a few years, and am currently setting up a car for COTA. I have tire pressures where I want them, and am working on the brake temps at the moment. On the straights, the brakes are right where they should be, with both fronts and rears around 600°F right up to the braking zone, then increasing under heavy braking.

Right now, the fronts are getting around 200° hotter than the rears in the braking areas, which makes sense as the braking forces shift the vehicle's mass forward. However, every setup guide I read makes no distinction between fronts and rears, only saying that the brakes in general should reach a certain target range (say 1100-1200°F) during braking.


So I'm left wondering if I should be shifting my brake bias to the rear in order to bring the rear temps in line with the fronts? I'm concerned that this rear bias will cause the rears to be more prone to locking up, making it not worth the effort. I suppose I can always compensate by other means, but first I just would like to know if the bias adjustment is the correct approach, or whether having disparate temps front and rear are normal.

Any ideas?

MaximusN
08-11-2017, 17:04
I would not bother about the rear temperature as long as they are not overheating. Because if the balance at the current temperatures is okay and steady, that's all that counts. Messing with your balance is the worst thing you can do unless you want to solve overheating issues while in a race.

Schnizz58
08-11-2017, 17:05
You'll never get the fronts and rears equal because the bias is always going to be towards the front. You can push the bias back on some of the rear/mid-engined cars that have more weight in the rear (Porsche for example) but it will still be biased to the front. You're correct that running the bias towards the rear introduces the risk of locking up. I usually start at 50/50 and then move the bias forward until the rears stop locking up.

Fight-Test
08-11-2017, 17:46
I agree to get the balance correct then adjust the ducts and tire pressure to balance it out.

Here is my tune from Laguna we just ran. Not sure if you are in the Ligier Nissan but this was what I ran.

"Front/rear

Tires soft 1.45/1.42

Brakes 95%, bias 55/45, ducts 60/45 (note: I use 85% on brakes only because I use a very short throw on the brake)

Aero 6/14, bias 47. (can power oversteer on 4th gear corners so you could do +1 rear wing)

Rad 60

Can close brake ducts to maintain higher pressure and temp, but track temp will be falling through the race."

This will keep you right in your range over the hour and half for Laguna. Maybe you can compare to what you ran to give you a idea. I will give you what I use for COTA as soon as it gets tuned up. I was running softs also with no issues. I could easily triple stint at Laguna on softs with this setup.

Nyreen
08-11-2017, 18:09
FT is right. If you're not happy with the rear brake's temperature, mess with the vents. The bias isn't meant for that (unless mid-race heating issue).

In real life, locking the rear equals less troubles than lockin the front, because it just makes the rear loose. If you lock the front, you will make flat spots on your tires, and if you're unlucky, overcook the corner, understeer and crash.

But it's a game, so we don't care ! Yay ! I've seen Top leaderboard setups with 59% front bias on the 488 GT3. I usually run 53, 54 with this car, thus I can trail easily. It's mostly a matter of preference, but front brakes does the work better than rear brakes, so avoid losing too much braking forces in any way.

(They don't even use the rear brake in MotoGP. Only to correct speed mid-corner or stabilize the bike when getting back on throttle (which is also called left foot braking in automotive world))

eracerhead
08-11-2017, 19:39
Thanks for the tips, folks. My first inclination was as you all say; to not worry about rears and just keep an eye on max front temps. Glad to hear that, as it's a lot less setup work...! :) I think my ducts are in decent shape already based on my 'resting' temps being in the 600-degree zone.

And thanks for the glimpse into your setup, Fight; I run the Honda, by the way. I tested most of the week prior with Softs before making a stupid raceday decision to go to Hards for duration, and that was the absolute wrong tire to be on. With considerably less aero than you, I was dancing on the knife-edge the whole race..

hkraft300
08-11-2017, 21:14
There’s only so much work the front brakes and tires can do on their own. Together they’re more effective. I’ll tend to set bias back until the rear starts to lock, then move it a bit forward again. Max brake efficiency + safety.

Then adjust brake ducts to control temperature and tire pressure.





In real life, locking the rear equals less troubles than lockin the front, because it just makes the rear loose. If you lock the front, you will make flat spots on your tires, and if you're unlucky, overcook the corner, understeer and crash.


What?
When you lock the rear you can spin backwards into a wall. If you’re quick you’ll catch it. If it’s sudden there’s no recovery. If you lock the front first at least you can back off but you’re still pointed straight.
If you’re in a close race, you absolutely don’t want the rear snapping to the side because you’ll hit the car next to you.

So no, locking rears is not preferable to locking front tires.

You get flat spots on any tire (front/rear/left/right/car/bike) if you lock them for long enough.

MaximusN
08-11-2017, 21:33
What?
When you lock the rear you can spin backwards into a wall. If you’re quick you’ll catch it. If it’s sudden there’s no recovery. If you lock the front first at least you can back off but you’re still pointed straight.
If you’re in a close race, you absolutely don’t want the rear snapping to the side because you’ll hit the car next to you.

So no, locking rears is not preferable to locking front tires.

You get flat spots on any tire (front/rear/left/right/car/bike) if you lock them for long enough.

Indeed, I always set them in a way that when trail-braking my rears MIGHT lock. But never in a straight line, then it's the fronts that should go first.

kyoo
12-11-2017, 15:26
Hi, I have a noob question regarding brake bias:

In setup screen, moving to the right means from 60/40 to 58/42.
In car adjustment, adding brake bias goes 60-61-62-63.....

Can you guys tell me which way is front and rear in each situation? Thanks.

hkraft300
12-11-2017, 19:40
60/40 Is Front/Rear in setup.

I’m guessing it’s going towards front in the ICM menu.