Kale2000

I have small cracks by where the rotors are drilled and have a trackday, so can I do the trackday without any worries and then buy new rotors or will it be too dangerous. They are less then a 1/4 inch from the drill holes. Please advise

ErnieN85

if you can catch a finger nail in them they are too big otherwise they are normal

CHJ In Virginia

I agree with the above post. Catch a fingernail in a crack and it is time to swap out the rotor. If you are going to continue to track the car - get solid rotors. The drilled ones have considerably shorter lifetimes than the solids.

Kale2000

wow! Thats great info. No they dont catch a fingernail. There just there, very small and I didnt even think about wide! There just small and there just there and that alarmed me. Thanks for that

jwg2

Yes, spot on advice. I'll add a couple of lessons learned to the thread. These cracks will definitely grow, and eventually find the outer edge of the rotor, and that will be it for that rotor. If you have the misfortune of having a rotor crack on the track, it will feel like you have a flat tire whenever you apply the brake. Take it right to the pits when that happens.

I do inspect my rotors twice between sessions, once after coming off the track and once again after a full cool down. My experience is that usually when they crack, it is in the paddock as they cool.

I've tried any number of solutions, but if you run an aggressive pad at the track you will consume rotors. I've tried expensive, I've tried cheap. I have found the most cost effective solution is to go with something like the stock AC-Delcos or similar quality and plan to replace them every couple of weekends. Avoid cheap foreign parts. The expensive stuff will last longer, but not enough to justify the cost delta.
I have not tried cryo-treatment, but folks say that it makes a big difference. That is my next experiment. The recent issue of GRM also recommended upsizing the break kit to get better life out of rotors. When the budget allows I will try that.

I have found that spindle ducts will extend the life of the rotors a useful amount.

I now always come with a spare set of rotors just in case.

braknl8

It would be a fairly good idea to go ahead and purchase solid rotors to take with you to the track. No sense in letting a cracked rotor ruin your weekend... you can swap it out should the drilled ones give up the ghost, in less than 10 mins.

braknl8

as well as hubs/bearings. this should be one of your first mods.

BEZ06

If they look like this - no problem:





However, they'll develop into cracks like this - and you can keep running them, but keep a real close watch on them:






Here's one that I need to swap before my next track event, which will be the NCM Sebring HPDE the end of this month:






Ultimately any small crack will probably end up like this:





And here's another one - I've got several more that are acting as doorstops and ballast around the shop!!




Bottom line - watch small cracks closely, because they WILL develop into large cracks!!! I always have a couple backup rotors at a track event.

Bob

argonaut

I agree with most of this but would like to add a few comments:

Thru personal experience, talking with guys at the tracks and reading forums like this over the past 5 years I've come to conclude the following:
- Rotor usage/cracking is HIGHLY dependent on: how aggressive are the pads, how sticky are the tires, the conditions driven, the tracks driven, weight of car, cooling ducts or lack of and an individuals personal braking style.
- Because of this - some people get unbelievable wear out of a set of rotors while others, using the same rotors get about 2 days.
- In general - high quality 2-piece rotors will significantly out last OEM replacements. However, whether or not they are more cost effective is all over the map. Case in point - I went thru a set of the AP Racing 2-piece rotors in about 10 track days. I've personally talked to a couple racers who have got over 20 race days out of them. For me they haven't been cost effective. For them they have been.
- Ducting is often touted as a must-have to increase the life of rotors. I've come to question that on *some* tracks. Specifically tracks with very long straights such as VIR. The cracking is caused by the extreme temp differentials and usually happens on cool down in the paddock. But with ducting on a very long straight, the temp differential is significant on every lap. There are more than a few hard core track junkies who plug their ducts on a track like VIR.
- Regarding cryo treatment - from what I've see the jury is out. I've not seen enough evidence either way to convince me it's worth the extra dollars or not.

eogel

Several years ago I had rotors cryo treated for wheel to wheel racing. Did not make enough difference in life to do it again. Don't forget to include cost of shipping both ways when you evaluate this.

Kale2000

wow. All you guys are great!!! AND THOSE PICS ARE CRAZY!!! No hang nail, and they dont look like those pics!! thanks guys!!

JeremyGSU

Very true. Everyone always says "well, I got this out of them" so everyone else thinks they should too. Every track is different, etc like argonaut said. My home track is Sebring and is very hard on brakes. When I go to Road Atlanta, even VIR, they are so much easier on the brakes it's ridiculous. I've done two days at VIR and two at Sebring on my AP rotors. The first two were wit Ferodo Uno's and the second with XP20s. I may not have re-bedded them in right but how they are looking right now I think I can get two more days out of them and they will be toast.

MarkDFW

Cheapest route seems to be napa blanks, but they crack fast.

Next option would be something like centric blank rotors. These seem to be stronger. I currently run these in the rear since the rear doesn't take as much braking force as the fronts.

Strongest is a two piece rotor. I have stop tech st60 big brake kit up front, and run their two piece rotors on the front only.

I think this will prove to be a cost effective setup long term since 80% of braking force is up front.

StreetSpeed

FYI tirerack sells centric rotors that are already cryo treated. I'll be ordering a set soon to have as backups when my slotted DBA rotors poo the bed.

rithsleeper

No one mentioned this yet: proper cooling techniques can really extend the life of your rotor. After you come in after the cool down lap, drive around the paddock for at least 5 minutes. Then after you park continue to roll your car back a few feet every two min. the brake caliper holds more heat in the rotor so it will not cool evenly. By continually moving the car you make sure the rotor cools evenly. Less stress for it to crack. I've never cracked a rotor on the track only in the paddock.

+1 for cheaper rotors. I use brakemotive here on the forums. He is always willing to work with you and pretty reasonably priced.

Kale2000

Everyone has such good imput... Ive learned alot from this post, and wanna thank you for your imput... I'll get new ones. I just wanted to make sure i didnt go and they break on the track and end up wadding up the car, and maybe taking someone else with me. those pics of the rotors were awesome... thanks again

Kale2000

So awesome!!! Your pics are amazing... And no, my rotors dont look like those!!! Lol