F/R brake temperature?

ValidusVentus · 09-24-2019, 10:10 PM

Quote:

Originally Posted by SouthArk370Z

A lot of variables involved - pad composition, rotor material/construction - but 190F sounds reasonable to me. The fronts are doing a lot more work so they naturally get hotter, ie, you can't expect the temps to be all that close. You should be paying more attention to balancing the brakes and don't worry about the temps so much. If you are balanced now, more aggressive brakes will throw the balance off.

Indeed. To expand on that a bit; the ideal brake balance of the car is dictated by how much traction is available at either end of the car under maximum braking. The traction available is dictated by the tires, weight balance of the car, and the weight transfer that takes place at maximum braking. The amount of weight transfer is dictated by the wheelbase length, the weight of the vehicle and the rate of deceleration.

In effect this means that with grippier tires, more weight transfer will take place and the front brakes should be, and will be able to, do comparatively more of the braking work since they have more weight over their tires. Conversely, with less grippy tires or when its raining, at maximum braking, less weight transfer will take place (because you cant brake as hard) and a setup where there is less of a front biased braking force -still front biased though- will then provide the most overall braking ability. That's why, a bit counter-intuitively imo, racecars or cars with adjustable brake bias like mine need to run more rear bias in the wet than in the dry to maximize their braking capability.

Hotrodz · 09-25-2019, 08:52 AM

Quote:

Originally Posted by ValidusVentus

Indeed. To expand on that a bit; the ideal brake balance of the car is dictated by how much traction is available at either end of the car under maximum braking. The traction available is dictated by the tires, weight balance of the car, and the weight transfer that takes place at maximum braking. The amount of weight transfer is dictated by the wheelbase length, the weight of the vehicle and the rate of deceleration.

In effect this means that with grippier tires, more weight transfer will take place and the front brakes should be, and will be able to, do comparatively more of the braking work since they have more weight over their tires. Conversely, with less grippy tires or when its raining, at maximum braking, less weight transfer will take place (because you cant brake as hard) and a setup where there is less of a front biased braking force -still front biased though- will then provide the most overall braking ability. That's why, a bit counter-intuitively imo, racecars or cars with adjustable brake bias like mine need to run more rear bias in the wet than in the dry to maximize their braking capability.

Well said one of the best explanations on brake balance I have read in a while.

Rusty · 09-25-2019, 10:20 PM

Quote:

Originally Posted by Hotrodz

Well said one of the best explanations on brake balance I have read in a while.

obender66 · 09-27-2019, 05:25 PM

Quote:

Originally Posted by ValidusVentus

Indeed. To expand on that a bit; the ideal brake balance of the car is dictated by how much traction is available at either end of the car under maximum braking. The traction available is dictated by the tires, weight balance of the car, and the weight transfer that takes place at maximum braking. The amount of weight transfer is dictated by the wheelbase length, the weight of the vehicle and the rate of deceleration.

In effect this means that with grippier tires, more weight transfer will take place and the front brakes should be, and will be able to, do comparatively more of the braking work since they have more weight over their tires. Conversely, with less grippy tires or when its raining, at maximum braking, less weight transfer will take place (because you cant brake as hard) and a setup where there is less of a front biased braking force -still front biased though- will then provide the most overall braking ability. That's why, a bit counter-intuitively imo, racecars or cars with adjustable brake bias like mine need to run more rear bias in the wet than in the dry to maximize their braking capability.

Thank you, that is a great insight. My problem is that it is very difficult to quantify by seat of the pants traction available. Car slows down, I do not crash, I do not get brake fade after 25-30 minutes on the track (I get tired before my brakes are) it slows down in the straight line, save for crap on the track but am I optimized?

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