Wonder if these have another day in them? (rotors)

[yandy]

I'm fairly close to convincing the boss that I "need" a BBK, so don't want to make the investment fo $800+ for front rotors right now. Now the BBK may happen before my next track day anyway (March 29-30), but in case it doesn't. I'm wondering if these would be ok to run. They're micro-cracks, but noticing that they're starting to span from hole to hole.

P.S - I know there's threads on here about this, but don't want to hijack others.

Any input is appreciated.

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Thanks for looking

[Jon H]

General rule of thumb is if you can catch one of the cracks with a fingernail, it's probably not safe to run.

[USCTrojanMan29]

Originally Posted by Jon H

General rule of thumb is if you can catch one of the cracks with a fingernail, it's probably not safe to run.

I thought the rule of thumb is to replace the rotors if the cracks extend from one hole to another and/or from a hole to the edge of the rotor.

[klammer]

They look fine to me and that's why you don't run drilled rotors on the track, they always crack around the holes in a relatively short time and both responses above are correct from what I've heard.

[Estoril Blue]

In those pics they appear okay to run. The two rules above both apply. Also no chunks or missing material - or other obvious issues and of course, they need to be within spec (are they?).

*Always* inspect after every session.

[bigjae1976]

I would say no. There's a crack in the 3rd pic that runs to the edge...that would be no good.

[CanAutM3]

Originally Posted by USCTrojanMan29

I thought the rule of thumb is to replace the rotors if the cracks extend from one hole to another and/or from a hole to the edge of the rotor.

Exactly my rule.

In the pics, I see quite a few cracks extending from one hole to another and a few extending to the inner edge. The worst cracks are the ones that extend to the outer edge, which I don't see in the pictures.

Using them one more time would be on borrowed time and taking chances. Examine them closely and if you do find cracks that extend to the outer edge of the disc, I would definitely recommend not using the rotors any further.

On a side note, the disc wear does not look very nice (circumferential ridges and grooves). What pads are you using?

[admranger]

Originally Posted by Jon H

General rule of thumb is if you can catch one of the cracks with a fingernail, it's probably not safe to run.

Originally Posted by USCTrojanMan29

I thought the rule of thumb is to replace the rotors if the cracks extend from one hole to another and/or from a hole to the edge of the rotor.

You're both right.

Either/Or. Of course, if you don't have drilled rotors you need a rule of thumb and that's the first one. If you have drilled rotors, both apply.

There is a third test, the "float test". Toss these rotors into a body of water. If they float, you can use them.

My two decades of experience on track in HPDE's, instructing, and racing say these rotors are toast. Toss them in the recycle bin.

Oh, you don't need a BBK. Sorry.

Get some PFC direct drive rotors and pair them with PFC pads (Z-rated for street, '08s for HPDE). Extra cooling won't hurt you...

FWIW, I ran my E46M3 at Spring Mountain in a somewhat spirited manner (USC and others can confirm) with DD rotors and PFC '06 pads. 0.001" of wear on each rotor. The track isn't the easiest on rotors (easier than Laguna, but much harder than BW, WS, or Chuckwalla imho). Cool weather helped. No braking drama at all. I have less than 0.050" of wear left on the rotors. No cracks.

[dapopa9]

usually say run them tell the crack...as in basically break

[yandy]

Originally Posted by Jon H

General rule of thumb is if you can catch one of the cracks with a fingernail, it's probably not safe to run.

Originally Posted by USCTrojanMan29

I thought the rule of thumb is to replace the rotors if the cracks extend from one hole to another and/or from a hole to the edge of the rotor.

There's a bit of both here, I don't exactly catch the cracks with my nail, but enough to feel the bump.

Originally Posted by klammer

They look fine to me and that's why you don't run drilled rotors on the track, they always crack around the holes in a relatively short time and both responses above are correct from what I've heard.

Originally Posted by Estoril Blue

In those pics they appear okay to run. The two rules above both apply. Also no chunks or missing material - or other obvious issues and of course, they need to be within spec (are they?).

*Always* inspect after every session.

Thickness is within specs, cracks are the worrisome bits.

Originally Posted by bigjae1976

I would say no. There's a crack in the 3rd pic that runs to the edge...that would be no good.

Thanks for the input, seems like new rotors coming in, regardless of BBK decision if not on time.

Originally Posted by CanAutM3

Exactly my rule.

In the pics, I see quite a few cracks extending from one hole to another and a few extending to the inner edge. The worst cracks are the ones that extend to the outer edge, which I don't see in the pictures.

Using them one more time would be on borrowed time and taking chances. Examine them closely and if you do find cracks that extend to the outer edge of the disc, I would definitely recommend not using the rotors any further.

On a side note, the disc wear does not look very nice (circumferential ridges and grooves). What pads are you using?

I've been using Carbotechs for a while now, they're supposed to be "easy" on rotors. But heat down here is not exactly easy on anyone, specially during the summer months.

Originally Posted by admranger

You're both right.

Either/Or. Of course, if you don't have drilled rotors you need a rule of thumb and that's the first one. If you have drilled rotors, both apply.

There is a third test, the "float test". Toss these rotors into a body of water. If they float, you can use them.

My two decades of experience on track in HPDE's, instructing, and racing say these rotors are toast. Toss them in the recycle bin.

Oh, you don't need a BBK. Sorry.

Get some PFC direct drive rotors and pair them with PFC pads (Z-rated for street, '08s for HPDE). Extra cooling won't hurt you...

FWIW, I ran my E46M3 at Spring Mountain in a somewhat spirited manner (USC and others can confirm) with DD rotors and PFC '06 pads. 0.001" of wear on each rotor. The track isn't the easiest on rotors (easier than Laguna, but much harder than BW, WS, or Chuckwalla imho). Cool weather helped. No braking drama at all. I have less than 0.050" of wear left on the rotors. No cracks.

Thanks, only thing with the PFC and RB rotors are the price? for a grand more or so, I can get a front BBK, and probably save myself in the long run on PADS. That of course is just a theory, no direct experience.

Thanks for the input.

---------------------

Thanks to all for the feedback, looks like I'll be replacing them one way or another.

[LiM3y]

I replaced mine long before they looked like that...for me, if it is enough to worry about, it is enough to change. I don't want to spoil my fun by worrying about my rotors as I hit my braking point at 125mph on the front straight...

[yandy]

Originally Posted by LiM3y

I replaced mine long before they looked like that...for me, if it is enough to worry about, it is enough to change. I don't want to spoil my fun by worrying about my rotors as I hit my braking point at 125mph on the front straight...

Absolutely, the only reason I brought it up it's difficult to dish out $1k for rotors, if BBK may come after. Hoping I have a decision soon, on either direction, but you're absolutely right. If I even have to ask, then they should be coming out regardless.

[Sebringjetta]

Originally Posted by bigjae1976

I would say no. There's a crack in the 3rd pic that runs to the edge...that would be no good.

thats what the rotors you sold me look like.....just kidding i dont think they look bad but mentally you have kind of screwed your self as next time you track you will in the back of your head be wondering if your brakes are ok so it might be a good idead to change them....you never want to second guess things when your on the track...just my 2 cents

[yandy]

Originally Posted by Sebringjetta

thats what the rotors you sold me look like.....just kidding i dont think they look bad but mentally you have kind of screwed your self as next time you track you will in the back of your head be wondering if your brakes are ok so it might be a good idead to change them....you never want to second guess things when your on the track...just my 2 cents

agreed, if I'm going to be questioning it, then it probably isn't safe for more than physical reasons. I will order a front set to be safe, then worry about the BBK.

[pkimM3r]

was wondering where yandy went!

[yandy]

Originally Posted by pkim1079

was wondering where yandy went!

Yandy was taking care of some personal stuff, home refi things like that. But done with that for now, ready to play

[Sleeper519]

People love to tell other people that they don't need a BBK. So,hey, we really don't NEED an M3 either...

Just get an ST-60 for the front and be done with it. You want it and you're tracking a fair amount on the hot S.Fla. tracks. I wouldn't spend the money on the PFC DDs and then turn around and finally get the BBK.

Just do it, you'll be glad you did.

[yandy]

Originally Posted by Sleeper519

People love to tell other people that they don't need a BBK. So,hey, we really don't NEED an M3 either...

Just get an ST-60 for the front and be done with it. You want it and you're tracking a fair amount on the hot S.Fla. tracks. I wouldn't spend the money on the PFC DDs and then turn around and finally get the BBK.

Just do it, you'll be glad you did.

The BBK is going in sooner or later, just doing the convincing "the boss" thing for now. I won't spend the money on the PFC DD's, just not worth it to me. BBK is higher up-front but will pay off later on.

I just need something between now and when the BBK finally comes in.

Thanks for your feedback.

[dmw16]

I see connecting cracks. That's the point where they are clearly toast. Get new rotors, or rather than spend that money, just get a BBK and call it a day. When you get your BBK get solid (or slotted) rotors. Drilled rotors are (as you see here) not ideal.

[Groundpilot]

Originally Posted by Sleeper519

People love to tell other people that they don't need a BBK. So,hey, we really don't NEED an M3 either...

Just get an ST-60 for the front and be done with it. You want it and you're tracking a fair amount on the hot S.Fla. tracks. I wouldn't spend the money on the PFC DDs and then turn around and finally get the BBK.

Just do it, you'll be glad you did.

Sorry for the off topic question, but doesnt ST-60 front only puts too much front bias with stock rear brakes? I hear that if you install front bbk only, ST-40 is the way to go. I need to reaserch more on this, because i will be installing front bbk, not rear as i think it will be more than enough for HPDE type of driving.

[yandy]

Originally Posted by Groundpilot

Sorry for the off topic question, but doesnt ST-60 front only puts too much front bias with stock rear brakes? I hear that if you install front bbk only, ST-40 is the way to go. I need to reaserch more on this, because i will be installing front bbk, not rear as i think it will be more than enough for HPDE type of driving.

This is something I've been wondering as well, good question.

[bigjae1976]

Originally Posted by Groundpilot

Sorry for the off topic question, but doesnt ST-60 front only puts too much front bias with stock rear brakes? I hear that if you install front bbk only, ST-40 is the way to go. I need to reaserch more on this, because i will be installing front bbk, not rear as i think it will be more than enough for HPDE type of driving.

No, the bias is fine with an ST60. I still wished I got an ST40. More wheel choices (you can run 17s), more pad choices, cheaper pads and thicker pads.

ST60 is just a PIA when it comes to street wheels unless you want to run 19s. I like 18s.