Wilwood Brake Rotors- Check Em!

[Si.G]

Yet another post - but adds information to the story.

I have cracks in the middle of the friction surface on my car and I think I know how I did it.

Car...
B6T running about 200rwhp, Wilwoods on the front (BP10 pads initially), SE brakes on the back, running Yoko A050 soft

NOTE - I read this post before I fitted my brakes and torque'd up the disc to top hats as per 949 racing specs.

History...
Done about 1500km maximum on the brakes, this is a motorsport only car
Did 14 motorsport events on the BP10s including 2 tracks events with stops from nearly 200km/h
No cracks noticed at this point.
Switched to BP30 pads and bedded them in as per instructions.
1 motorsport event later and cracks have appeared.

On the first run of the last event the brakes totally faded on the 3rd corner. The 1st and 2nd stops in the events were from about 110km/h and then 140km/h. I think the issues was that the brakes were stone cold at the start, they had dríven about 50m. I think the rapid temperature change is what hurt the discs and it also glazed the pads, I had to go out onto the road and bed them the pads in again to bring them back. They worked perfectly for the rest of the event.

In addition to the above, I also have horrible shuddering and noise just as you come to a stop, from about 20km/h down to 0.

[Danny]

Those rotors aren't designed for hard track work. Ideally they should be full floaters. The rates of expansion for the mounting bolts, discs and hats are very different especially with the heat generated by the track and cause the cracks.

Actually they have lasted well and a new set will be cheaper than converting to full floaters. Floaters can rattle too in daily use.

[plohl]

^you can get semi floating rotors which use a spring washer to align them when they're not being used. Prevents the rotor moving when it's not in use.

Sent from my SM-N9005 using Tapatalk

[madjak]

I think track use is less stressful on the rotors than time attack style sprints where you are launching from cold straight into hard braking and getting them to full temp by the end of the run. Then they get to cool down rapidly and repeat 5 times. On the track I get my rotors up to temp a bit slower on the warm up lap.

So far I've had no issues but I'm checking my rotors between events and I'm running the 949 torque specs. I'm working on setting up some ducted cooling to them as the temp colouration around the bolts is very prominent. I'll have to take a photo but are they meant to go purple or is that getting too hot?