Quote:
Originally Posted by The HACK
So the question here is, how exactly do you alleviate the additional heat generated by faster laps? There are two ways to solve this. One is to upgrade the equipment. The other is by extending your braking zone, start your braking early and do the majority of your braking early in the braking zone to allow your system a longer period of time to cool down. The key in the 2nd method, is you MUST only do the same amount of braking but do it early enough so you can carry the same speed through the turns.
|
Right, the second method is pretty much what one must do if one needs to manage the thermal issues without upgrading equipment.
Another way to look at this is in terms of acceleration and deceleration "zones." By definition, when you are accelerating, you are picking up momentum and building up kinetic energy, and when you are decelerating, you are losing momentum and converting kinetic energy to heat.
The fast driver will have a much longer acceleration zone than the slower driver because he/she will get on power much earlier (coming out of the turn), and he/she will brake later (by more consistently threshold braking at the limit and trail braking when appropriate). So, the faster driver will spend more time on power per lap. Some of that "extra" energy pumped into the system is used to overcome the increased drag due to going faster, some of it is scrubbed with the tires by being more aggressive at corner entry (I took me some time to get that concept and you kind of think it is not possible until you see someone else do it and start being more aggressive yourself), and some of it ends up in your brake system.
So, to manage the brakes, one needs to shorten the acceleration zones like you are saying and limit the top speeds. In other words, get off the power earlier than you could have, brake earlier and with less line pressure, but shoot for same the corner entry speed. Alternatively, you can just get off the power and let the car coast for a second at the end of the straight before braking (well, coasting is really decelerating since there is drag).
In terms of where to measure temperatures: you are correct that there are several things going on. These are the main components that can fail:
1. Brake fluid
2. Pad
3. Rotor
4. Caliper (mainly the pistons)
5. Brake lines
Any of the above can fail independently. And, yes, measuring rotor surface temperatures will not tell the whole story. Fluid temperature can vary depending on the design of the caliper and pads (dimensions and materials). But it is very difficult to objectively determine the local temperature of the fluid in the caliper--I don't know of a system that can report that. Pragmatically speaking, all one (a weekend warrior) can proactively do is to monitor rotor temperatures and try to infer if the fluid might be at risk of overheating or not. Of course, one can and should be reactive and back off if the pedal starts getting soft or if the stopping distances increase due to pad fade.
I think one should just generally back off if rotor temperatures after a cool down are ~600C. That's not a very accurate way of diagnosing anything, but it's better than not paying any attention to what your brake system is doing and then being surprised by something going horribly wrong.
Also, I learned not to put too much faith in the pad manufacturer's specs. The HT10s that self-destructed on me where supposed to be good for ~750C, and I don't think they got there, but I have no way of knowing the peak on-track temperatures (the rotors were at ~600C at the paddock). In comparison, I had Pagid RS19s on the day before that, and even though they had a slightly lower temperature rating, they held up. Well, they cost twice as much though.
Finally, operating at such a high temperature range cannot be good for the rotor itself as far as how it is stressed thermally.
OP, did you ever figure out what happened to your brakes?