ptindall

Hi guys. I was cracking front rotors and getting brake fade on my street tire, 350whp, '01 Z06 so I bought and installed the DRM ducts and LG spindle brackets. And after one HPDE, I still cracked my new rotors and have a spongy pedal. I kind of expected my problem to go away after the ducts. Anything else I should look at or do to help my rotors and brake fuid live longer? Thank.

new Hawk HP+ pads.

ATE racing blue fuid

street tires

NAPA rotors

braided steel lines

If any more info would help, just ask.

geerookie

Completely flush the old brake fluid. Replace the factory aluminum caliper pistons with stainless steel from DRM. Also while you're doing it replace seals etc. with GM caliper rebuild kit...about $15 from Gene at partswarehouse.com Do front and rear with the rebuild kit.
When you're on your last lap don't use the brake pedal if possible and when you stop no E brake and move it back and forth about 2 feet after a few minutes. When you stop with hot rotors and park it the pads hold the heat on that spot and can cause cracking when cooling.
Other than that use more of the right pedal and less of the middle one! I've been running NAPA rotors and the same pads at a few different tracks with no issues. I get about 16 track days on a set of rotors and 3 days on pads.

John Shiels

ti shims and change your braking style. You shouild get 2-3 days with them. Season them and cool them better before you come to rest.

Gray Ghost GS

It might be your braking technique on the road course. I tend to brake late, hard and short - giving the brake rotors/pads more time to cool. Some people that are new to HPDE and building confidence in the car tend to brake too early and 'ride' their brakes creating excessive heat and reducing cooling time between applications. I figured it might be worth checking. Good luck, Mike

ptindall

I do completely flush the brake fluid and I try to not touch the brakes after the checked flag. And while I don't move the car after it's parked, I get even cracking around the rotor, not just where the pad is. But rebuilding with stainless pistons is something I had not thought of. That is exactly what I'll do next. Thanks for the response!

ptindall

I'd like to buy the ti shims. Can you inform me who sells them?

Also, what does, "season them" mean? Thanks for the help!

ptindall

Actually, I brake hard and short when not held up by traffic, but where I race, most of the time I am behind slower traffic and do a much longer, softer brake. Seems like you are changing the same amount of kenetic energy into heat either way but if this does generate a lot more heat, than that certainly could be part of my problem. Thanks for the post.

FasterIsBetter

IMHO, stop wasting your time with the stock brakes. I was having similar problems with my brakes, although not cracking rotors. But I was eating up brakes, even with the Hawk HP+ pads, stainless lines, etc. I finally got the LG Wilwood SL6/SL4 kits, with Wilwood aluminum hat rotors, Wilwood H pads. The braking performance is 100x better than the stock brakes, and the pads last forever. Plus the rotors look like they are brand new after 5 track events.

Upgrade the brakes and stop fighting with the inferior stock brake setup.

zsnnf

You might try Cryo treating the rotors. I would crack a set of rotors at every open road race. After treating them I have 3 seasons with no cracks.

ptindall

I understand your position. I just can't drop $2600 plus the cost of new wheels and tires. (I'm nunning stock size 17") I'd love to but I'm just too poor for that. From what I've read on the forum, I should be able to get away with stock brakes as I'm only at 350whp and running street tires. If the concensus was that the stock brakes just can't take it and upgrading is a must, I wouldn't be trying to fix the problem with band aids. But some really expirienced people are not saying that.

ptindall

Interesting. I have seen Cryoed rotors for sale. Do you buy then that way, have them done somewhere, or what?

jcmbird

after talking to a metalurgist, cryo is no help. maybe hype

RedLS6

You're fine with stock brakes and NAPA rotors, as long as you don't mind changing the rotors every few track days. Your rotors should be able to last longer than 1 track day, though, through some changes in your braking style.

I have found the opposite from what some have posted......when I brake hard and late, my front rotors are cracked after one day.....sometimes after one session, running either Wilwood or Carbotech pads, and slicks! Going into the braking markers at 2 (VIR) and hammering the brake pedal helps my lap times, but kills my rotors quickly.

I normally brake a little earlier when I'm not trying for a record lap, and get 3 track days from a set of rotors. The kinetic energy dissipated is the same, the heat transfer is slightly different due to the contact time (just don't excessively drag the brakes), but the mechanical stresses in the rotor are greatly reduced with earlier braking. Mechanical stresses created by braking torque in the rotor (along with thermal) contribute to the development of microscopic cracks, which become larger and visible as the rotor cools. This has worked for myself and several others.

ptindall

This makes very good logical sense to me. However, I did not realize that going through rotors even every three track days was normal. I've got another question for you guys. What is your take on not replacing the rotors when all you can see is the very small, very fine little cracks in the center of the pad mating surface that do not extend beyond? I will admit, I had them when I went to the track a couple weeks ago and could not tell a difference in performance. At the end of the day, the cracks were maybe a tad larger, but not even enouph that I could say for sure they had grown.

wallyman424

rule of thumb, replace when:

1.) there is a crack that propagates continuously along the entire rotor face.
2.) when you can catch your nail in it

the hundreds of little cracks are no big deal.

VetteDrmr

This sounds odd to me; exactly what kind of cracks are you seeing? If they're "spiderweb" type cracks that cover the center surface of the rotor then you're OK. I've autocrossed with rotors full of surface cracks for the past three years with no problems.

OTOH, if it's a crack that's broken through the outer edge of the rotor, then it's probably toast.

HTH, and have a good one,
Mike

RedLS6

The small, fine cracks will not hurt your braking performance or compromise your safety. I sometimes replace my rotors when the cracks become wide enough to catch my fingernail, or approach within 1/8 inch of the rotor edge.........but 95% of the time, I toss the rotor when the one "big" crack reaches the outer rotor edge.

This normally occurs as the rotors cool, 20 to 30 minutes after the car is parked, after a session. When the crack reaches the outer edge, the rotor is trashed, and is non-driveable. You'll feel a lot of pedal vibration if you try to drive it. Again, the rotor should be mechanically OK when you are on track, but the crack will expose itself and grow afterwards during the cooldown. Always inspect the rotors after the cooldown time.

Like others have said, pay attention to your cooldown, do a cooldown "lap" around the pit roads, don't use the e-brake, and don't let hot pads stay parked over the same spot on the rotor if you pull off track and stop. And, experiment with your braking style, early vs. late. Most of us HPDE'ers have a stack of cracked rotors.......I just took about 16 of them to the recycler last month.

ptindall

Oh. I guess I was making a big deal out of nothing. :o Yes, all I'm getting is the little surface cracks. I didn't know that was okay. I'm glad I asked. Thanks for the help everyone. I think I'll do the stainless pistons and ti shims if I can find them to help my brake fluid anyway.

gkmccready

Um, make sure you have your rotors on heading the right direction, if you don't the rotors wear very badly. I had mine on backwards by mistake and they definitely take a huge beating that way. They do much much better on the right way.

(Kind of makes you wonder about GMs decision not to have left and right side rotors on the C6.)

Last C5

Don't put the ti shims on the backs of both pads, just the back of the piston side pads. Putting them on both pads holds too much heat in the pads and slows down the dissipation.