# 18" Wheels on a ZCP



## Ajax (Feb 1, 2002)

There's a little devil on my right shoulder saying "Just call them, what could it hurt to go look?"

There's a little angel on my left shoulder saying "Eighteen inch track wheels won't fit over the bigger brakes."

Which should I smack?


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## Nick325xiT 5spd (Dec 24, 2001)

17" track wheels cover the current brakes.

Of course, the bigger brakes are a DOWNGRADE for track use if you drive hard. Those drilled rotors will not withstand heat cycles very well.


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## elbert (Mar 28, 2002)

It might depend on which wheel. Stock 18's might need a spacer, SSR Comps probably won't. It's all a guess at this point. 

re: Nick's point...it's ironic that the brakes in "competition" package is probably less track worthy than non-ZCP's. Short of upgrading to a BBK, don't know how easy it will be for ZCP'ers to find non-x-drilled rotors.


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## e36M3r (Oct 19, 2004)

Yes of course the CSL brakes are a "downgrade" thanks for the info, :snooze: 


Nick325xiT 5spd said:


> 17" track wheels cover the current brakes.
> 
> Of course, the bigger brakes are a DOWNGRADE for track use if you drive hard. Those drilled rotors will not withstand heat cycles very well.


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## Ajax (Feb 1, 2002)

So, I guess we know that the brakes are pretty much just a cosmetic upgrade, and we don't know if stocker 18"s will fit over them.

Sum it up?


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## Nick325xiT 5spd (Dec 24, 2001)

e36M3r said:
 

> Yes of course the CSL brakes are a "downgrade" thanks for the info, :snooze:


 Yes. Believe it or not, performance cars don't necessarily have things done for purely performance reasons. The CSL rotors may work better... But they won't last nearly as long. And having seen cross drilled rotor failure before, I have ABSOLUTELY NO INTEREST in tracking a car with drilled rotors.

Ever hear about that $8,000 ceramic brake upgrade that Porsche offers on the GT3? Those rotors will last a few days of hard track use and then they crack. And then you're **** out of luck. Here's a hint: Don't speak if you have no idea what you're talking about. It looks bad for you.


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## Nick325xiT 5spd (Dec 24, 2001)

AJAX said:


> So, I guess we know that the brakes are pretty much just a cosmetic upgrade, and we don't know if stocker 18"s will fit over them.
> 
> Sum it up?


 Given that the current brakes are less than an inch smaller, and people can clear larger rotors on BBKs with 18s, I'd say the odds are extremely low you'll have trouble with 18s.


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## Technic (Jun 24, 2002)

Nick325xiT 5spd said:


> 17" track wheels cover the current brakes.
> 
> *Of course, the bigger brakes are a DOWNGRADE for track use if you drive hard. Those drilled rotors will not withstand heat cycles very well.*


I have read your comments about drilled rotors being cracked by the heat in track use in many of your posts about M3 brakes, does this heat craking applies to the _floating and drilled_ rotors or just to drilled?


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## e36M3r (Oct 19, 2004)

Yes, I can see you are basing your fear on the time you saw a cross-drilled rotor fail... I think you are being a bit extreem when you keep trying to push the notion that it is a "downgrade". There seems to be another motive in your strenuous pushing of that word.

Why must you denigrate a package that is superior in performance to the one you happened to purchase? You could mention that the performance may be enhanced but the longevity decreased... instead you choose to play the "downgrade" which is total bull shiite!

The green monster appears to be lurking within you mate. 

I hope you take your own advice. Enough said :beerchug:



Nick325xiT 5spd said:


> It looks bad for you.


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## Nick325xiT 5spd (Dec 24, 2001)

e36M3r said:


> Yes, I can see you are basing your fear on the time you saw a cross-drilled rotor fail... I think you are being a bit extreem when you keep trying to push the notion that it is a "downgrade". There seems to be another motive in your strenuous pushing of that word.
> 
> Why must you denigrate a package that is superior in performance to the one you happened to purchase? You could mention that the performance may be enhanced but the longevity decreased... instead you choose to play the "downgrade" which is total bull shiite!
> 
> ...


 I'm basing this on the collective experience of everyone who's used the brakes on the track who says that they are inadequate. M3 CSL owners who track hard report that their brakes fall apart.

Have you ever heard of the notion of reality? Facts are facts, and the drilled rotors are a DOWNGRADE for those of us who drive our cars HARD. If they weren't, I'd retrofit them in an instant. M3 brakes are pretty crappy at high speeds as a general matter. There have been many reports of the BMW drilled rotors failing, and I've seen some pretty ugly cracking on a set of them with my own eyes. If you can't cope with reality, that's fine, but get over this notion that something MUST be better just because it's on the CSL.

The one thing I want from the ZCP package is the steering rack. And you know what? I may very well install it. Let me repeat: Do not confuse facts with reality. Anyone who's talking about tracking a ZCP with real brake pads MUST know that they need to pay VERY careful attention to the condition of their rotors. Have you ever seen what happens when a rotor suffers catastrophic failure in motion? It instantaneously LOCKS up the wheel, and not even releasing the brakes will unlock it generally. And that's if you're lucky and it doesn't start throwing chunks of metal into other components.

Maybe it's just me, but I value my safety. Drilled rotors are only good for the track when you're willing to replace them VERY frequently.

If I haven't said it before, I'll mention it here. This is NOT specific to BMW rotors. I've seen Brembo BBK rotors with nice cracks in them too.


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## Nick325xiT 5spd (Dec 24, 2001)

Technic said:


> I have read your comments about drilled rotors being cracked by the heat in track use in many of your posts about M3 brakes, does this heat craking applies to the _floating and drilled_ rotors or just to drilled?


 Anything drilled. Floating rotors aren't immune.


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## elbert (Mar 28, 2002)

Technic said:


> I have read your comments about drilled rotors being cracked by the heat in track use in many of your posts about M3 brakes, does this heat craking applies to the _floating and drilled_ rotors or just to drilled?


It applies to all drilled rotors, not because of the floating design. (edit: as Nick just said)

The scientific explanation is the holes themselves are stress risers, more so if the holes are drilled than cast. The drilling process can cause additional problems--microscopic flaws are introduced in the material, and with the repeated cycling between high temperatures and cooling (which is severe even in normal driving, but more so under track usage), these flaws propagate and become much larger cracks.

The same applies to slotted and dimpled rotors--the machining introduces flaws. However, the problem isn't as severe since the machining doesn't go through the rotor as in cross-drilled rotors.

You will note most professional race cars that still use iron rotors don't use x-drilled rotors. Maybe slotted, but not cross drilled.


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## Jim in Oregon (Dec 23, 2001)

When I bought my 2002 M3 SMG 2 years ago I "upgraded" to the cross-drilled floating Euro rotors and pads. It cost me I think somewhere in the neighborhood of $900+. After 2 track days and 1500 miles, the front rotors warped. The dealer told me they wouldn't cover them under warranty as they were a "performance" item. I switched back to the stock rotors and I haven't had a problem since. While the cross-drilled rotors look cool, they really act like cheese graters and totally fill the holes with brake dust. I was constantly using a small screwdriver to clean out the little holes. The rotors didn't crack but of course I only had 1500 miles. They were warped so badly that by just spinning the rotors slowly you could see how bad they were.....never again.

Now slotted rotors....



e36M3r said:


> Yes, I can see you are basing your fear on the time you saw a cross-drilled rotor fail... I think you are being a bit extreem when you keep trying to push the notion that it is a "downgrade". There seems to be another motive in your strenuous pushing of that word.
> 
> Why must you denigrate a package that is superior in performance to the one you happened to purchase? You could mention that the performance may be enhanced but the longevity decreased... instead you choose to play the "downgrade" which is total bull shiite!
> 
> ...


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## bren (Jul 1, 2002)

Technic said:


> I have read your comments about drilled rotors being cracked by the heat in track use in many of your posts about M3 brakes, does this heat craking applies to the _floating and drilled_ rotors or just to drilled?


I think you probably mean 2 piece rotors as "floating" defines the caliper and its relationship with the disk. The benefit of 2 piece rotors is in keeping heat from the disk away from the wheel bearing.

FWIW, I cracked a set of drilled rotors on my Grand Cherokee after little more than a year of regular use....no way would I trust them on a track car.


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## Ajax (Feb 1, 2002)

All in all, good advice on rotors. Thanks guys.


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## stylinexpat (May 23, 2004)

BMW will replace them under warranty. So one can drive them hard and then get them changed under warranty as they are stock brakes..


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## Nick325xiT 5spd (Dec 24, 2001)

stylinexpat said:


> BMW will replace them under warranty. So one can drive them hard and then get them changed under warranty as they are stock brakes..


 If that doesn't help you if they fall apart while you're at the track...

And BMW would most likely have something to say if you came in for new brakes once a month. We're not talking about using these with stock pads. We're talking about serious track pads.


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## Moderato (Nov 24, 2003)

So the cross-drilled rotors on the ZCP will perform better then the standard M3 rotors, but will have to be replaced much more often?


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## Jim in Oregon (Dec 23, 2001)

stylinexpat said:


> BMW will replace them under warranty. So one can drive them hard and then get them changed under warranty as they are stock brakes..


Kiss off warranty on the brakes....BMW will take one look at the blue burned rotors and say "No way". $1K for new rotors.


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## elbert (Mar 28, 2002)

Moderato said:


> So the cross-drilled rotors on the ZCP will perform better then the standard M3 rotors, but will have to be replaced much more often?


In the short term, the ZCP rotors might perform marginally better. They are a larger size, and can exert more torque. And if true floating rotors are used, the brake pads will have slightly better contact than a floating caliper setup.

However, not only do the drilled rotors have problems with cracking, but warpage as well. With the reduction in mass comes a lowered resistance to warpage. No free lunches.

All in all, it's probably a disservice to have the ZCP rotors if the car will be tracked. They won't be covered under warranty or maintenance plans. And if the owner had an unlimited budget to replace these rotors, he/she probably would get a BBK anyway.


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