Brake Rotor Deposit/Grooving

[Slideways]

This could be it - this was my first outing with coilovers, that plus cooler weather and better driving resulted in going from a 1:29.1 to a 1:25.9. Do you guys know if running different compounds front/rear messes with the brake bias too much? I'm thinking of keeping HPS in the rear (to keep costs down) since there's a ton of meat left on my 1st set, and getting DTC-60s on the front next year.

It could. According to this chart, the DTC-60 and HPS have a very different coefficient of friction and temp operating window:

[timmo]

It looks like you need a dedicated track pad. Perhaps your driving skills are improving and you are carrying higher speeds and braking later than before.

Came here to say this.

This could be it - this was my first outing with coilovers, that plus cooler weather and better driving resulted in going from a 1:29.1 to a 1:25.9. Do you guys know if running different compounds front/rear messes with the brake bias too much? I'm thinking of keeping HPS in the rear (to keep costs down) since there's a ton of meat left on my 1st set, and getting DTC-60s on the front next year.

[foolio]

It looks like you need a dedicated track pad. Perhaps your driving skills are improving and you are carrying higher speeds and braking later than before.

Came here to say this.

[Slideways]

It looks like you need a dedicated track pad. Perhaps your driving skills are improving and you are carrying higher speeds and braking later than before.

[timmo]

Did this happen on all 4 corners? How do all of the pads look? I’ve seen this before with a sticking caliper causing brake drag and overheating the material.

I haven't gotten a chance to take stuff apart so I can't comment on the pads. This was the front LH corner, makes sense as it's a RH track - front RH corner was similar but not as bad. Rears are fine.

This is my rotor before this last track day, after 3 events with HPS pads:



Perhaps I should go for a casual drive, then check if the areas near the wheel bearing are hot. However I did street drive it and autox it quite a bit with the current pads before this outing and they seemed to be ok

[racinghart]

Did this happen on all 4 corners? How do all of the pads look? I’ve seen this before with a sticking caliper causing brake drag and overheating the material.

[timmo]

Does anyone know what would cause this? This is after 1 track day with HPS pads and Zimmermann rotors. I know, I know... HPS aren't meant to be track pads, but I haven't had any issues with them aside from going through pad material like crazy. I ran 4 track days with the first set I bought and the rotors had a bit of grooving, but nothing abnormal. Pad thickness is about equal inside and out, from what I can see without taking the caliper off.

Truth be told it might be my fault because I didn't bed the pads in when I replaced them - however I thought that was only necessary when switching pad compounds, and since I was replacing old HPS pads with new HPS pads, I wouldn't have to do so. Perhaps that would do it?