Possibly overcooling brakes with ducting...

[dre99gsx]

Looking for some advice from you racers. I've been battling braking issues where out of ~20 lap sessions, the first 4-5 hard laps are nice and consistent braking. Once I get to 6-10+, it feels like I'm reaching pad fade - I have to brake earlier and push the pedal down harder to slow down.

On some occasions, I come in the pits and notice my brake pad is leaving small bits of disintegrated material on my rims.

This is stoptech caliper, 355x32 rotor, PFC11 pads. I run 3" cooling ducts to the front only.

I tried some temperature paint this weekend and all 4 rotors hit the beige color = 1460F+. I'm sure I'm hitting 1600F.

So as an experiment, I blocked my cooling ducts, went out for two hard sessions. Magically, I had consistent braking power throughout the entire session.

Granted it was 50F out, but this is at NJMP. Fairly long straigths between braking applications, and a long carousel.

Could my ducts be so efficient that I was cooling my brakes to too much, putting the pads outside of their zone? I always thought you want as much cooling as possible, but starting to think this isn't the case.

I am going to continue running like this, but my other problem to solve is reducing the high heat. I think I need more thermal mass (380mm rotors, or 355x34 if they make them, or I don't know what else exists...)

[dre99gsx]

I'm running the PFC11. You can see the image where I'm assuming my temperature range sits: (1) hottest at the end of a braking zone, and after a medium to long straights, it cools down to (0), which could explain why I suddenly have a longer braking distance at the same pedal pressure (and I measure brake pressure via a sensor to corroborate).

I used to run the 08 pads, and may go back to them. You can see that they have a fairly consistent mu (or braking friction) within that zone. That may give me best of both worlds - allow me to use brake cooling ducts but maintain a consistent brake pedal.

Cons are slightly longer braking distance needed (less friction), but possibly shocking the rotors from the constant rapid cooling between turns.

Not sure what I should be aiming for.

[Michael9218]

I also have the Stoptech 355 kit with PFC11 pads. I removed my brake cooling ducts years ago. Similar issue. Even at Road Atlanta, which is pretty hard on brakes, I felt the brakes were getting over cooled between braking events. I get better initial torque without the cooling. Haven't had a problem with heat related fade.

[dre99gsx]

Oh wow, this is great to hear! Then I'm not losing my mind. Thanks for the feedback and confirmation.