[Mr. 5]

Originally Posted by The HACK

I am the technical director of one of the LARGEST BMW CCA chapters in the country. I am also a driver's coach and a driving instructor for several High Performance driving schools. I work freelance closely as a developer and tester for a respected brake company. My full time job is at a SEMA FOUNDING MEMBER company. I am a fully accredited freelance journalist for the automotive industry covering aftermarket parts. I have personal friends who drive race cars for professional teams such as Turner Motorsports...I can list more if you want.

I have spoken with my high school buddy who worked for BREMBO regarding drilled and slotted rotors. What he told me would back up my bold statement. He had flat-out stated that cross-drilling and slots, FOR STREET APPLICATION, is a pure marketing gimmick. It simply means they get to charge more for the rotor that cost the same, or less, to make.

Go talk to some of the local instructors at BMW CCA events and see what they say or think about "dimpled" rotors and slotted rotors for street or track use.

Now that I've shared my qualifications, might I ask, what do YOU do that makes you an expert on brakes, besides putting a few on your car and driving them up and down the street a few times?

COLOR="White"]p.s.: And if you believe all that b.s. I just listed, I've got a bridge in Brooklyn to sell you too.[/COLOR]

Yah, I don't believe you, but I will admit that the pads could have less life with slotted rotors than without slotted rotors.
As far as the slots not doing anything at all--I completely disagree.
The slots grab the hot gasses and debris from the pad and swipe them away.

[Alpina_B3_Lux]

Originally Posted by stressdoc

Oooh, and while I'm at it, there are maybe 5 different companies offering stainless steel brake line sets. What are the best ones?

I'm not in a position to compare the steel brake lines, but I'm going with Goodridge. They have an excellent reputation here in Europe and are TUV approved in Germany.

Alpina_B3_Lux

[O-cha]

Originally Posted by Mr. 5

I read that and you should read it too.
If you read about the direction of the slots then you will see that the direction of the slots doesn't matter. it's the direction of the cooling vanes in the rotors that matter. The pictures are an example.

As a primary yes, the vanes are what matters, as I stated..., after that for slots it is quite debatable regarding the leading edge of the slot. If you have a choice, it should be the outer diameter edge that is leading If you don't consider getting different rotors because the "engineers" don't know what they are doing. You will see the directional vanes of the two largest brake manufacturers (brembo/stoptech) correspond to this direction of the slots, for reason. I'm sorry that the article I linked did not include that info, but I just clicked the first thing google popped up and assumed. I apologize.

Originally Posted by Mr. 5

As far as the slots not doing anything at all--I completely disagree.
The slots grab the hot gasses and debris from the pad and swipe them away.

No one said at all, he said on the street, as in where you brakes will never get hot enough to outgas on the street, and most compounds don't even have the problem on the track.






Fact is arguing that putting dimples in rotors is nothing more then a gimmick is ignorant. They don't serve any of the function drills and slots do, but still have the same negative side effects (with exception of looking cool in some peoples eyes)

[stressdoc]

Here are the ECS kit ($130), Goodridge kit ($160), and Stoptech ($166). ECS might be the only one with the middle lines [note: Goodridge also has 6 piece kit w/midlines]

[Mr. 5]

Originally Posted by O-cha

As a primary yes, the vanes are what matters, as I stated..., after that for slots it is quite debatable regarding the leading edge of the slot. If you have a choice, it should be the outer diameter edge that is leading If you don't consider getting different rotors because the "engineers" don't know what they are doing. You will see the directional vanes of the two largest brake manufacturers (brembo/stoptech) correspond to this direction of the slots, for reason. I'm sorry that the article I linked did not include that info, but I just clicked the first thing google popped up and assumed. I apologize.

No one said at all, he said on the street, as in where you brakes will never get hot enough to outgas on the street, and most compounds don't even have the problem on the track.

No worries. Before I put the slotted rotors on, I did some research with the way people have them installed, and I'll agree that most vendors and car manufacturers have the slots in the way you describe.
I was also thinking of it as a circular momentum thing as well, where as the heat on the inside surface of the rotor is going to push it's way to the edge of the rotor. If the slot hits the inside part of the rotor first then it will transfer the hot gasses to the edge of the rotor.

I agree that some people concentrate too much with the outer slots instead of worrying about the inner vanes and some engineers reverse the pattern.

[GreenPlease]

I'll just come out and say it: I think drilled/slotted looks cool and I'm willing to pay extra despite the lack of "street" benefits.

[O-cha]

Originally Posted by Mr. 5

No worries. Before I put the slotted rotors on, I did some research with the way people have them installed, and I'll agree that most vendors and car manufacturers have the slots in the way you describe.
I was also thinking of it as a circular momentum thing as well, where as the heat on the inside surface of the rotor is going to push it's way to the edge of the rotor. If the slot hits the inside part of the rotor first then it will transfer the hot gasses to the edge of the rotor.

I agree that some people concentrate too much with the outer slots instead of worrying about the inner vanes and some engineers reverse the pattern.

It's more to do with the way the slot contacts the pad, with the leading edge on the outer edge of the rotor it will scrub the pad more, which is the whole point.

One could make an argument as well that the outer edge is hotter do to higher speeds and more surface contact, but IDK bout that.

[O-cha]

Originally Posted by GreenPlease

I'll just come out and say it: I think drilled/slotted looks cool and I'm willing to pay extra despite the lack of "street" benefits.

Which is fine, half the crap we put on our cars is performance inspired lets just quit trying to argue otherwise.

[The HACK]

Originally Posted by Mr. 5

Yah, I don't believe you...

Right. Asking for "qualifications" on the intarweb is basically an open invitation for an all out LIE. And even if I were to tell the truth and share with you what makes me such a brake expert, it's not likely any one of you will believe me ANYWAY. So why bother questioning my authority on the matter, when you yourself haven't provided YOUR qualifications, and whatever qualifications you CAN provide to prove you're such a brake expert, I won't believe anyway?

Would have been easier to just leave it at "you're righ HACK. You're ALWAYS right HACK."

[The HACK]

Originally Posted by Mr. 5

[/B]

Yah, I don't believe you, but I will admit that the pads could have less life with slotted rotors than without slotted rotors.
As far as the slots not doing anything at all--I completely disagree.
The slots grab the hot gasses and debris from the pad and swipe them away.

Back to the topic on hand. How long a set of pad lasts, has a lot more to do with how well the rotors evacuate heat, than if it's slotted or not. Heat, is the reason why brakes work, and it is also brake system's biggest enemy. If you can put a set of 2 piece rotors that is capable of drawing in more air through the center vanes than the 1 piece that typically comes with most BMWs, that'll go a much longer way to extend the pad and rotor life. Heck, if the 2 piece rotors are slotted, vs. the OEM blanks, the pads on the 2 piece floating rotors will LAST LONGER than the blanks. Bank on it.

Now, back to myth number 2: Modern pads no longer OUT-GAS. They haven't out-gassed like pads in the 60s and 70s for DECADES. The whole excuse "drilled rotors and/or slotted rotors" help with out-gassing is nothing but marketing ploy by companies that make drilled and/or slotted rotors to keep selling rotors that cost the same to make for 2X the margin.

Someone mentioned it earlier about slotted/drilled rotors in the rain. There's some truth to that. In the wet, either slotted or drilled rotors will allow the brake system to evacuate water from the friction area quicker. HOWEVER, the draw-backs to the function of drilled rotors for motorsports or even street application outweigh the minor benefit they offer in the wet, and since ALL BMWs now come with the brake drying feature, it makes the reason for having drilled/dimpled/slotted rotor purely AESTHETIC.

There are benefits to having slotted rotors, but not for out-gassing purposes. Slotted rotors prevent, to a degree, pads from glazing up. And that is pretty much the only benefit...Although there are none of the draw-backs of drilled rotors on a slotted design.

[Alpina_B3_Lux]

Originally Posted by The HACK

Someone mentioned it earlier about slotted/drilled rotors in the rain.

That would be me.

There's some truth to that. In the wet, either slotted or drilled rotors will allow the brake system to evacuate water from the friction area quicker. HOWEVER, the draw-backs to the function of drilled rotors for motorsports or even street application outweigh the minor benefit they offer in the wet,

I disagree. Pursuant to my experience, the benefit is anything but minor. As mentioned earlier on, with blank rotors the reaction time of the brakes was substantially increased, and with slotted rotors they grabbed almost immediately. If you've ever been in a situation where you had to react very fast (and if you've driven any car for more than a trip to the supermarket I would imagine you have), you cannot seriously describe the benefit as minor. And I'm not even talking about the car veering to one direction due to uneven brake forces applying to the front, which at high speeds is quite a horrifying experience.

and since ALL BMWs now come with the brake drying feature, it makes the reason for having drilled/dimpled/slotted rotor purely AESTHETIC.

As mentioned earlier on, a number of owners (in Germany) have complained about the effect I described earlier on, and all of them had cars with the brake drying feature. It would seem it only works when your swipers are engaged, and even then not always ideally. I had that experience as well in hard rain and with swipers engaged, so I would maintain my opinion that slotted rotors (don't know about drilled ones) can be of quite a benefit in these situations. For me that would, without any doubt whatsoever, justify spending some €€ or $$ on slotted rotors.

Alpina_B3_Lux

[Alpina_B3_Lux]

Originally Posted by stressdoc

Here are the ECS kit ($130), Goodridge kit ($160), and Stoptech ($166). ECS might be the only one with the middle lines

No, that is not correct. I just got my set of Goodridge steel lines, and there are 6 of them - so they do provide you with the middle ones as well. I also think that I've seen these at around 140 $ somewhere, but in Germany I paid 140 EUR for them.

Alpina_B3_Lux

[Gen_E92]

I wish someone could make some two piece rotors for OEM calipers

[The HACK]

Originally Posted by Alpina_B3_Lux

That would be me.
I disagree. Pursuant to my experience, the benefit is anything but minor. As mentioned earlier on, with blank rotors the reaction time of the brakes was substantially increased, and with slotted rotors they grabbed almost immediately. If you've ever been in a situation where you had to react very fast (and if you've driven any car for more than a trip to the supermarket I would imagine you have), you cannot seriously describe the benefit as minor. And I'm not even talking about the car veering to one direction due to uneven brake forces applying to the front, which at high speeds is quite a horrifying experience.

As mentioned earlier on, a number of owners (in Germany) have complained about the effect I described earlier on, and all of them had cars with the brake drying feature. It would seem it only works when your swipers are engaged, and even then not always ideally. I had that experience as well in hard rain and with swipers engaged, so I would maintain my opinion that slotted rotors (don't know about drilled ones) can be of quite a benefit in these situations. For me that would, without any doubt whatsoever, justify spending some €€ or $$ on slotted rotors.

Alpina_B3_Lux

Well, since I live in an area where it rains about 3 days out of the year, I will leave the expert commentary about slotted/drilled rotor's effectiveness up to you. However, I did manage to drive my car in one of those 3 days of rain at the track, and have driven the other two days in the rain in a year with AND without slotted brakes...And frankly, the difference is minor (in my opinion). Maybe it's because I've been taught and have continue to teach to look way ahead and react before reaction is required to minimize having to deal with emergency braking situations, or god forbid, if you DO have to deal with emergency situations you're already mentally prepared for it...

[The HACK]

Originally Posted by Gen_E92

I wish someone could make some two piece rotors for OEM calipers

The "respected" brake manufacturer that I do R&D and test for that I mentioned above are looking into it. If I have my say, it will likely happen before the end of the year. If and when that happens I'll let you guys know.

Of course, I could just be bs'ing about "working" for said brake manufacturer...

[stressdoc]

Originally Posted by Gen_E92

I wish someone could make some two piece rotors for OEM calipers

I posted some above from Stillen.

[stressdoc]

Originally Posted by Alpina_B3_Lux

No, that is not correct. I just got my set of Goodridge steel lines, and there are 6 of them - so they do provide you with the middle ones as well. I also think that I've seen these at around 140 $ somewhere, but in Germany I paid 140 EUR for them.

Alpina_B3_Lux

Excellent, it is hard to tell from the limited info on the listings and generic photos. The fittings on the Goodrich set look high quality.

At this point I am looking at Stillen rotors, Goodrich lines, and those CC pads that Craig raves about.

[Alpina_B3_Lux]

Originally Posted by stressdoc

Excellent, it is hard to tell from the limited info on the listings and generic photos. The fittings on the Goodrich set look high quality.

That's true! I dropped them an e-mail to be sure. The lines do look great quality, and they give you an unlimited warranty on them, which says something.

At this point I am looking at Stillen rotors, Goodrich lines, and those CC pads that Craig raves about.

Similar to what I'm doing - EBC rotors, Goodridge lines and also the CC pads. I sure hope the latter don't squeal, but Craig (and others) says they don't, so I'll give them a try. Install will only be at the end of September or beginning of October, though. When do you plan to do it?

Alpina_B3_Lux

[stressdoc]

At this point I might try and delay until spring.

[Pyrat 2]

Seems to be a lot of discussion around the usefullness of the rotors for street use. I tend to believe that there is probably little benefit for street use. However, I track my car and autocross it regularly. Both are actually fairly hard on the brakes and I'd be intrested in peoples views for these applications.

One benefit to slotted rotors that I have read is that they tend to give you more even brake/rotor wear, as measured across the surface of the rotor, than regular rotors. This is something that I would like as I can't help but think that this uneven wear is affecting my performance. You can see the pictures of one of my front rotors and understand why I would like to get more uniform wear.

Then there is the issue of eliminating float from the gassing that occurs at high temps like that seen on the track.

[stressdoc]

Any news on when ATE might release rotors for the 335 (front)?

Some "unnamed" high tech rotors got dissed in the latest Roundel.

[Mr. 5]

Originally Posted by HeelToe

Seems to be a lot of discussion around the usefullness of the rotors for street use. I tend to believe that there is probably little benefit for street use. However, I track my car and autocross it regularly. Both are actually fairly hard on the brakes and I'd be intrested in peoples views for these applications.

One benefit to slotted rotors that I have read is that they tend to give you more even brake/rotor wear, as measured across the surface of the rotor, than regular rotors. This is something that I would like as I can't help but think that this uneven wear is affecting my performance. You can see the pictures of one of my front rotors and understand why I would like to get more uniform wear.

Then there is the issue of eliminating float from the gassing that occurs at high temps like that seen on the track.

Those are some great pictures man!
I should take some pictures of my Cquence rotors now that they are completely broken in.