Do these rotors have two more weekends in them?

[dmw16]

How many days do these rotors have left? I am running pfc01 pads and am also now moving to nt01 tires which I know will stress my brakes more than my PSS tires did.

Speed wise I've started to move up to the intermediate run group. So I'm far from fast but I'm running faster than I was my first few days.

I would love for these to last 4 more days at NJMP Lightning.

Any chance?

Thanks.

[Estoril Blue]

Are they well within spec?

[dmw16]

Originally Posted by Estoril Blue

Are they well within spec?

Thickness wise, yes. My only concerns were the cracks.

[Porschefile]

likely yes.

[Estoril Blue]

Originally Posted by dmw16

Thickness wise, yes. My only concerns were the cracks.

I'd say yes. Just keep an eye on the cracks.

[WarrantyTracker]

I attended a talk last weekend at VIR from a speed shop owner. He said rotor cracks are not a problem until they get to the outside edge. The thing is, he also said M3 rotors get cracks in the "sandwich" of the two plates which you can't see. I'm not sure where that leaves us on rotor cracking. It leaves me "nervous."

[dmw16]

Originally Posted by Estoril Blue

I'd say yes. Just keep an eye on the cracks.

Sounds like I can at least run one weekend and then reevaluate. For the second I may opt to pick up a second set and just have them at the ready.

Thanks for the feedback guys.

[arter]

Turner is a good place to get replacement stock rotors....

[klammer]

Looks to me like you could run a whole season on those. Cracks are almost inevitable, especially on drilled rotors, but if they're not close to the edges, so should be OK. just watch and make sure the cracks aren't going out to the edges and you should be fine. These are brakes, so as always, better safe than sorry.

[bigjae1976]

No cracks that extend to the edges or connect two holes. If you think your close, don't forget to check the backside of the rotors.

[jml]

Those look new....those cracks are totally fine. Drive faster

[CanAutM3]

Originally Posted by bigjae1976

No cracks that extend to the edges or connect two holes. If you think your close, don't forget to check the backside of the rotors.

+1

IMO, Those rotors are fine. I have run rotors with way more cracking without issue. I have never had a rotor failure. As others have said, just watch for cracks that connect holes together and especially cracks that reach to the outside edge of the disc (which I have personnaly never seen on my car). You should be good for more than 2 days with these rotors.

[dmw16]

Originally Posted by jml

Those look new....those cracks are totally fine. Drive faster

I'm working on it. Each session as I add seat time I add speed

[admranger]

The rule of thumb is that if you can catch your fingernail in a crack, then the rotors are done.

Get PFC direct drive rotors and be done with it.

[OSAB1]

Toast. Don't play around with your safety. Get new rotors.

[jml]

Originally Posted by OSAB1

Toast. Don't play around with your safety. Get new rotors.

Be prepared to change rotors once a day then.

That is nothing.

[admranger]

Originally Posted by jml

Be prepared to change rotors once a day then.

That is nothing.

Attachment 891110
Attachment 891111

I raced a stock class E36M3 for years. It weighed in at 3175 lbs dry without anyone in the car (that was the minimum weight spec). Add in 180 lbs of a suited up driver, then add fuel and in an enduro it could tip the scales at 3500 lbs. My rotors were simple blanks and when the cracks got bad enough you could catch a fingernail, they went into the scrap pile. Hardly ever got to that point, though when they did, there was still plenty of material left (e.g., above min thickness spec).

I have no idea what you are doing to your brakes to get that much cracking. Do you have any cooling duct work? Those are some serious cracks. Silly big, in my opinion.

Knock yourself out if you want to run those. Just don't crash into me or take any of my track time while they scrape you off the barrier. 'k?

[dogbone]

I have AP Racing rotors. They crack quite a bit with race pads. Stillen is the official distributor of AP Racing. When I sent them pictures like the one below of my rotors, they said it was no problem and to keep running them.

They said keep running them until either the cracks show up at the edge of the rotor, or the rotor width goes below minimum spec width.

I kept running them, and they were fine. The rotor width went below minimum spec before any cracks went to the rotor edge.

[jml]

Originally Posted by admranger

I raced a stock class E36M3 for years. It weighed in at 3175 lbs dry without anyone in the car (that was the minimum weight spec). Add in 180 lbs of a suited up driver, then add fuel and in an enduro it could tip the scales at 3500 lbs. My rotors were simple blanks and when the cracks got bad enough you could catch a fingernail, they went into the scrap pile. Hardly ever got to that point, though when they did, there was still plenty of material left (e.g., above min thickness spec).

I have no idea what you are doing to your brakes to get that much cracking. Do you have any cooling duct work? Those are some serious cracks. Silly big, in my opinion.

Knock yourself out if you want to run those. Just don't crash into me or take any of my track time while they scrape you off the barrier. 'k?

They were pretty worrisome to me as well, but PF said that was fine and not to worry until they get to the edges or were all the way through. The issue is cooling as far as I can tell - but not what you expect. I think the forced cooling on the RS is so much more effective than "no cooling" on the E90 that the cracking is made worse by repeated extreme heating and cooling cycles on track.

But in general the OP's rotors are totally fine.

[MilehighM3]

How is it that people are saying get new stock rotors here? It certainly appears the OP has a bbk. You should be fine for a couple days, just keep an eye on them. Next time you get rotors or rings, switching to slotted will eliminate the possible cracks between holes. I'm not saying slotted don't crack, but in my experience they are more resistant to crack that their drilled counterpart.

[dmw16]

Originally Posted by Bmw135er

How is it that people are saying get new stock rotors here? It certainly appears the OP has a bbk. You should be fine for a couple days, just keep an eye on them. Next time you get rotors or rings, switching to slotted will eliminate the possible cracks between holes. I'm not saying slotted don't crack, but in my experience they are more resistant to crack that their drilled counterpart.

Yep, they are 355mm Stoptech rotors. I bought them used and the price was great, the only downside was the drilled rotors. I'll be switching when I replace them.

If I had known at the time that PFC was coming out with an E46 M3 ZCP upgrade kit I'd have waited, but what's done is done and I do like my stoptechs.