Cross drilled Rotors?

I would bet the cracking is from cheap-o's..... Or crazy heat on the track.

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OP,

You won't get your answer in this thread...you need to read many, many threads to know what the truth is.

I'll give you a hint. OE is in my opinion the best for the range of conditions your car will experience. It's not only the safe choice, but it's the safest choice.

You don't care about brake dust unless you're bothered more about appearance than stopping, and it's exactly the same with rotors. They're not on the car as a decoration, they're fn brakes...for, you know, stopping.

Brakes...for stopping. We don't care about dust or looking cool, we wants our bmws! OE. Face Munich, apologize for your thoughts...make roundel on forehead with brake anti-squel...you'll be fine!

Originally Posted by dmax

OP,

You won't get your answer in this thread...you need to read many, many threads to know what the truth is.

I'll give you a hint. OE is in my opinion the best for the range of conditions your car will experience. It's not only the safe choice, but it's the safest choice.

You don't care about brake dust unless you're bothered more about appearance than stopping, and it's exactly the same with rotors. They're not on the car as a decoration, they're fn brakes...for, you know, stopping.

Brakes...for stopping. We don't care about dust or looking cool, we wants our bmws! OE. Face Munich, apologize for your thoughts...make roundel on forehead with brake anti-squel...you'll be fine!

Do you do track time?

If answered no: Then you need not worry about cracked rotors due to heat. I'm sorry, but on the street there is no difference between the highest quality blank and the highest quality drilled rotors

If answered yes: You should be vary concerned with your brake fluid, pads and rotors. If you're out there for a long time going hard you will begin to see extremely hot temperatures. Brake fade due to temperatures and boiling fluid due to crappy brake fluid are not things you want to experience. High quality rotors will give high quality performance - they will have a low rate of failure.

OEM parts are not always best for track - please don't try to tell me otherwise. One can "get away with" lower quality blanks than with drilled. The the rate of failure will be much lower for cheap blanks than for cheap drilled.

I don't see anyone recommending he buy the cheapest drilled rotors he can - that would be stupid. Obviously only run drilled if you know that they are of sufficient quality for your needs, can spot problems before they hurt anybody, and accept the risks involved

I agree for the track, track pads are better, but they're worse on the street where most spend 99.9% of their miles, even if they track.

If you track a few times a year, then you'll be prepping your car anyway, wouldn't it make sense to put a track pad on it for that, and remove them to get the best pads for the street?

Oh, btw, did I hear the occasional street race? I'm sure you do it very safely, and haven't hit any of our children yet, so when you do street race, just make sure there aren't any people or cars around. You know this is real life, not a movie, right, OP?

Me and three of my friends have aggressive STREET pads and we have track pads that we switch in and out before and after each event. Even my friends M3 track car, he still switches to safe pads.

We're not discussing pads here, we're discussing rotors.

When was it suggested that anyone would be "street racing". Nobody runs in 25mph neighborhoods anyway

Originally Posted by Andy2108

Me and three of my friends have aggressive STREET pads and we have track pads that we switch in and out before and after each event. Even my friends M3 track car, he still switches to safe pads.

We're not discussing pads here, we're discussing rotors.

When was it suggested that anyone would be "street racing". Nobody runs in 25mph neighborhoods anyway

OP said he was street racing...no suggestion of it!

Sorry, yea, I went off on pads, but I will say that if OP is looking at rotors, then he'll be looking at pads too.

blanks are the best, slotted eat up pads, drilled crack though you get the best cooling.

Originally Posted by ///M=Power

blanks are the best, slotted eat up pads, drilled crack though you get the best cooling.

no they dont crack ive had my drileld zimemrmans for 8 months with very very aggressive street driving canyons runs twice a week and a few track days and they are still in great condition zero cracks

They look cool, but that's about it in terms of a street car. There are no downsides unless they are holes drilled in an already low quality rotor, or the holes are drilled too large and too close together by some idiot. Going with the bigger OEM names like Brembo, Balo, Ate, and Zimmerman is a pretty safe bet if you just want some nice looking rotors.

Originally Posted by El Polo

^those are cast perforated rotors if I'm not mistaken. They don't have the weakness of cross drilled ones by design.

Originally Posted by Andy2108

the OEM performance ones are cast perforated?

Originally Posted by El Polo

Zimmermann products seems to be cast perforated (even if vendors advertise them as cross-drilled... marketing...)

There is no such thing as rotors with "cast holes". It's a cost prohibitive idea with no benefits, as any hole, regardless of drilling or casting, is going to be a stress riser. If anybody actually finds any proof showing otherwise, I'd love to see it.

No problems here after 20k miles

Originally Posted by OrientBlau

There's blank (standard), drilled and slotted.

Blanks work the best. Period.

I think a 2-piece floating drilled design (like the 330 performance rotors and the rotors found on newer M-cars) would probably be better than single-piece blanks. The floating design allows for lesser weights and for lower overall brake temperatures. Both factors lead to better brake performance. While a blank floating rotor might be even better, they're not exactly common. I don't think any BMW has come with blank floating rotors since the E39 M5.

I don't think cracks will be a significant concern on a well-designed rotors. You don't really hear about the newer M cars cracking their rotors all the time.

Originally Posted by TerraPhantm

I think a 2-piece floating drilled design (like the 330 performance rotors and the rotors found on newer M-cars) would probably be better than single-piece blanks. The floating design allows for lesser weights and for lower overall brake temperatures. Both factors lead to better brake performance. While a blank floating rotor might be even better, they're not exactly common. I don't think any BMW has come with blank floating rotors since the E39 M5.

I don't think cracks will be a significant concern on a well-designed rotors. You don't really hear about the newer M cars cracking their rotors all the time.

Exactly. For all those about OE..well floating cross drilled rotors are factory equipment on the M3 ZCP and CSL. So where's your logic now. Not only as stated will they run cooler from being a floating hat design, weigh less for performance, directionally vented vanes, they also keep the heat away from the bearings compared to solid blanks.

Don't generalize here people. rusted poorly designed and made blanks can be much worse than a fairly good cross drilled(and vice versa). A good perforated floating hat design rotor is much better than a blank.

Originally Posted by TerraPhantm

I think a 2-piece floating drilled design (like the 330 performance rotors and the rotors found on newer M-cars) would probably be better than single-piece blanks. The floating design allows for lesser weights and for lower overall brake temperatures. Both factors lead to better brake performance. While a blank floating rotor might be even better, they're not exactly common. I don't think any BMW has come with blank floating rotors since the E39 M5.

I don't think cracks will be a significant concern on a well-designed rotors. You don't really hear about the newer M cars cracking their rotors all the time.

I agree with everything you say other than two things:

-Lower overall brake temperatures, no. What does a floating rotor have anything to do with the cooling of the rotor? If anything, overall temperatures might be higher since rotor heat can't travel to the top hat any more.

-Floating rotors are quite common when there is the money and the car ends up on the track. BMW used them stock on the E46 M3 CSL/ZCP and E92 M3. Look at any of the good brake kits for race use and they are almost always floating. Most factory race cars these days come with them from the factory.

Originally Posted by mkodama

I agree with everything you say other than two things:

-Lower overall brake temperatures, no. What does a floating rotor have anything to do with the cooling of the rotor? If anything, overall temperatures might be higher since rotor heat can't travel to the top hat any more.

-Floating rotors are quite common when there is the money and the car ends up on the track. BMW used them stock on the E46 M3 CSL/ZCP and E92 M3. Look at any of the good brake kits for race use and they are almost always floating. Most factory race cars these days come with them from the factory.

Well I was thinking lower temperatures for two reasons: A) aluminum is better at dissipating heat than iron. And B) Generally floating rotors also have directional cooling vanes - I don't think I've ever seen a set that didn't have them. I've yet to see a 1-piece rotor with directional vanes sold for the E46

For the second point - read my post more carefully. I said blank floating rotors, like the ones on the euro E36 M3 and euro E39 M5, aren't too common these days. The drilled ones like the ones found on the euro e46 m3, CSL/ZCP, and all recent M-cars are obviously fairly common.

Originally Posted by TerraPhantm

Well I was thinking lower temperatures for two reasons: A) aluminum is better at dissipating heat than iron. And B) Generally floating rotors also have directional cooling vanes - I don't think I've ever seen a set that didn't have them. I've yet to see a 1-piece rotor with directional vanes sold for the E46

For the second point - read my post more carefully. I said blank floating rotors, like the ones on the euro E36 M3 and euro E39 M5, aren't too common these days. The drilled ones like the ones found on the euro e46 m3, CSL/ZCP, and all recent M-cars are obviously fairly common.

Well, that separation and small contact area between the floating rotor surface and center hat brings heat transfer way down to negligible levels. The directional cooling vanes aren't a floating rotor specific thing either.

And yes, I did misread the "blank" floating rotor part. In response, I will post a picture of Performance Friction's really cool floating and dimpled rotors that they use on the Formula 1 C63 safety cars. Directionally vented, dimples with a nice radius, a special mounting setup that puts the top at bolts in double shear, and then there is the fact that they are like huge 15" rotors.

Originally Posted by mkodama

Well, that separation and small contact area between the floating rotor surface and center hat brings heat transfer way down to negligible levels. The directional cooling vanes aren't a floating rotor specific thing either.

And yes, I did misread the "blank" floating rotor part. In response, I will post a picture of Performance Friction's really cool floating and dimpled rotors that they use on the Formula 1 C63 safety cars. Directionally vented, dimples with a nice radius, a special mounting setup that puts the top at bolts in double shear, and then there is the fact that they are like huge 15" rotors.

Yea I should've been more specific. I think we're generally in agreement though

And those brakes are beautiful Makes the CSL brakes I'll be mounting next week look tiny

Originally Posted by theOSUbob

I don't think having cross-drilled (or perforated) rotors fail is a COMMON problem. I mean, let's be honest, just about every single high-performance car comes with them standard.

Ehh... I think its more for looks and in theory they are said to have higher performance...


I think it is pretty much proven that a blank is the choice for performance....



EX- Take f-1... Cost is not a factor at all and these cars are built for the best performance possible.... If drilled/ slotted performed better they would have them.




MOST true race cars are blanks...

Those are carbon-ceramic rotors on F1 cars. They operate differently than street car cast iron rotors. But even carbon ceramic brakes comes with drilled holes sometimes:

Originally Posted by mkodama

Those are carbon-ceramic rotors on F1 cars. They operate differently than street car cast iron rotors. But even carbon ceramic brakes comes with drilled holes sometimes:

lol at how much brake jobs costed on the porsches that had carbon ceramic brakes when I worked at the dealer.
If i'm not mistaken (its been a few years) I believe the rotors were around $800-$1000 each.