Brake swapping question

[jnjboc]

Hi folks,

I run Raybestos Quietstop ceramics on the street, and Carbotech XP9's front and rear for DE's.

AFter a 3 day DE last weekend, I put my almost new ceramics back on. I put them on the same wheel and orientation(inside/outside) as I had taken them off, to ensure a consistent pad "signature"-not sure if this is necessary, but I'm anal that way.

I noticed on my front rotor inspection before putting the ceramics back on, the tell-tale spider cracks had formed. Still about 2 inches from the outside edge, but I ordered new ones for my next DE.

So, I put my ceramics back on with the same rotors I used in the DE. The car stops fine, but the pedal feel is awful, compared to when I had the ceramics on before the DE.

there is a grinding, rough, almost pulsation feel. Is this just simply that the front rotors are shot(maybe the Carbotechs are not as rotor friendly as I thought?)

anyone ever experienced this?

[UstaB-GS549]

It could be pad material transfer to the rotors which the ceramics might scrub off after a while.

[wtknght1]

Yep, that's a big reason. Plus the fact that when you go out on track and 'abuse' the rotors and pads, you do wear off some of the rotor and groove it a little so it takes a while for pads to 'bed' in to this new surface. Imagine 2 records (if you can remember records) on top of each other. Each has small grooves so they won't be perfectly flat. It's the same for the brakes and rotors. Each has small grooves and it takes some wear to 'mate' them together. Those small spider cracks also reduce total surface area - that's why we always race with new rotors!

Man, with all this 'on top of each other' and 'mate' talk, I need a cold shower!!

Another thing is that you may have an air bubble or two in your brake lines. Just do a quick bleed on each caliper and I'm sure you'll be fine.

[Subdriver]

If you swap pads like that you should rebed them to get the old pad material off (Carbotech in this case) and the new pad material on the rotors.

And, as wtknght said, running on the track is hard on the fluid. I bleed after every session for this reason.

As an FYI, there is nothing wrong with swapping pads inside to outside. I do this all the time with mine to even wear (the inside pad wears slower as it is cooler).

[salvador]

If the brakes still work well, but you have a soft pedal, that definitely sounds like the fluid to me.

I wouldn't worry about the cracks until they get the edge.

What fluid are you using btw?

Sal