Arg,

At the track 2 weeks, as I was changing wheels, I noticed my right front rotor cracked in two places. Not sure if I did it then, 6 months prior, or if I bought the car like that in Feb '04.

Anyhow, I read and read and read, and replaced it with a used rotor from the salvage yard.

Went to Thunderhill Sunday, and after my first session of 25 min or so, I pulled the wheel to check, and sure enough, it was cracked. I took it easy, trying to warm them up, and I never got it to them HARD, like I did my first time driving the car. I'm running hawk blues, with my brake proportioning valve in the dead middle. It was windy, and very chilly.

I replaced the rotor with my spare and babied it the next session, working up to more braking. I never hammered it. I made it through the rest of the day, without a problem.

What are things that cause this?
What can I do in the future to prevent this?

Used brake rotors?
Packing the hub REAL full with grease?
Wheel bearing nut tightness?
Wheel bolt torque?
Air ducts? (to where, inside of rotor? hub?)
Warming up the brakes?

Thanks,

Todd

 

holy crap same problem as us outside right rotor cracked. we're thinking the caliper slider pins might just be stocking causing excess heat on the outside.

 

Were you having any brake pad wear issues? If so, check the sliding section of the caliper. I had a set that was really worn and wore the heck out of a set of brand new brembo rotors.

On the rotors, I've always heard that used rotors hold up a little better due to the number of milder heat cycles that they got through. Now, there are a lot of variables to that though.

If you haven't got ducts, they'll help a bunch. Duct them to the center even though it's a little harder to do correctly.

 

Thanks for the help!



The center of what? The center of the hub, or the center edge of the rotor?

 

For any kind of serious track work, you had better get used to going through rotors! Definitely duct air in, as this helps, but doesn't solve the problem. Us racers don't expect the "small" brakes (non-GSL-SE) to last more than a few week-ends at best. Heat just causes them to crack. I came off of a race at a track notorious for a hard braking zone this year with four cracks that ran all the way from hub to edge. I didn't realize it until I went out for the next practice and had hard rhythmic thumps through the pedal as the cracks went through the caliper. I needed to run the session, so I dragged the brakes until they warmed up. Once warm, they expand and press the cracks back together and they feel as good as new! Well - at least until they fly apart, but I didn't push them that far. I changed them before the next session, and always carry spares, prepped and ready to go on the car.

Rick

 

Me too, just did my ITA car last weekend. I made it all season on a set of rotors. I did crack a brake pad in the last race. Anyone have an easy technique for getting those races in the rotors?

 

The usual -

Take an old outer race that you have removed and grind it's exterior down a bit so it will slide in and out of the hub without sticking. Get a cheap aluminum bearing driver set and use the appropriately sized disk to knock the new race in. Just a few whacks with a mallet and they drive in great. No more screwing around tapping ad positioning - just a few straight drives on the tool.

Boswoj

 

The rotors are jsut too small for serious braking tracks and as such they wear out fast. I typically go through 4 new rotors in one season and two sets of hawk blues. This is with good brake ducting and a well maintained setup. really good ducting is the best thing you can do to prolong the life of your rotrs, but they are a consumable part. I usually wait until the local part store has a sale and then I buy a season's worth. I also have a spare set of bearings installed in a new set at every event just in case something happens.

my$0.02
-Trent

 

The rotor acts like a centrifugal pump, it pumps air from the center, thru the vanes, and then out the outer rim of the rotor.

Help the heat get out of the iron rotor and into the cooling air flow! Clean all the rust and dirt out of the rotor vanes. A metal gun cleaning bore brush on a power drill speeds this job up.

Make ducts to direct the cooling air to the center of the rotor, so that the rotor can then pump it thru the vanes like it wants to. This is so, so important for road race track brakes. Brake cooling ducts that stop short before the center of the rotor, or ducts that do not connect to the air dam up front are a joke. Ducts that give the air some place else to go besides the center of the rotor are not very effective.

 

how does air get to the center in a 1 piece hub/rotor assembly? not trying to be a smart ***. i don't see a way other than through the vanes first. This possibly another advantage to the 2 piece setups?

 

If you look on the back side of the rotor you can see where the vanes stop short of the "hat"/bearing area. The ducts I made go from a 2.5" circle down to a C shape that's about 3/4-1" wide at the center. The C shape encloses the front section of the vanes and is within 1/8" of the vanes.

 

Ducts! :TU:
Does the car have a front air dam? THat will help in mounting godo inlets onthe front.

Marcus

 

Buy Aluminum rotors

 

That's hillarious

 

Here you go, no more cracked brake rotors....

http://www.sevensonly.com/images/FRONT26.jpg

 

morbid curiousity...how much is that setup?

 

Price quote I received was $733.00. + calipers. I have to run stock SE calipers. I understand they work with those and aftermarket calipers. You can't run those rotors/hubs in any (SCCA) Spec or IT class. Production and GT only.

 

good to see that the rule has been clarified and these are allowed in ep.