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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > EBC dimpled & slotted rotors review????



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      08-13-2009, 05:40 PM   #1
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EBC dimpled & slotted rotors review????

has anyone had any experience with the EBC dimpled & slotted rotors on their car?

these rotors right here:


i'm looking to get these for the car to replace the oem rotors. they'll be paired with some ebc red stuff pads!

thanks in advance!
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      08-13-2009, 06:20 PM   #2
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Gimmick.
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      08-13-2009, 06:41 PM   #3
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care to elaborate......?
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      08-15-2009, 02:15 AM   #4
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anyone? no....?
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      08-18-2009, 02:27 PM   #5
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I'm curious 2.
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      08-21-2009, 04:58 PM   #6
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"Dimples" or slots does nothing for a street application. All those dimples will do is act like cheese graters on your brake pads, reduce overall sweep area, and introduce noise while braking.

Absolute marketing junk. You're better off buying factory blanks.
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      08-21-2009, 05:50 PM   #7
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Quote:
Originally Posted by The HACK View Post
"Dimples" or slots does nothing for a street application. All those dimples will do is act like cheese graters on your brake pads, reduce overall sweep area, and introduce noise while braking.

Absolute marketing junk. You're better off buying factory blanks.
LOL ..... ^^^^^ No noise, brake pads have no more signs of usage at this point than my OEM pads at time of replacement. The "sweep area" loss is so minimal that it makes no difference.

Dimpled, slotted or drilled rotors simply allow the rotor more effective cooling. The indentations on the rotor surface allow more air to flow between the rotor & brake pad surface. This also allows for less chance of brake fade with the proper brake pads in place.

I also have a set of rotors (different brand) that are slotted/dimpled in use with a set of the Cool Carbon brake pads. The rotors were installed before the pads and the stopping performance with the rotors in place was noticably better than OEM.

With the Cool Carbon pads installed the stopping performance between this setup & OEM is night and day.
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      08-21-2009, 09:44 PM   #8
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Quote:
Originally Posted by The HACK View Post
"Dimples" or slots does nothing for a street application. All those dimples will do is act like cheese graters on your brake pads, reduce overall sweep area, and introduce noise while braking.

Absolute marketing junk. You're better off buying factory blanks.
Will you give us your background so we can determine whether to take this comment and prove you wrong or either just completely ignore what you said?
I just did a review on my cheese graders.
http://www.e90post.com/forums/showthread.php?t=292297
I must have lots of mozzarella in my wheel wells.
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      08-22-2009, 01:24 AM   #9
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Quote:
Originally Posted by Mr. 5 View Post
Will you give us your background so we can determine whether to take this comment and prove you wrong or either just completely ignore what you said?
I just did a review on my cheese graders.
http://www.e90post.com/forums/showthread.php?t=292297
I must have lots of mozzarella in my wheel wells.


Quote:
Originally Posted by The HACK View Post
"Dimples" or slots does nothing for a street application. All those dimples will do is act like cheese graters on your brake pads, reduce overall sweep area, and introduce noise while braking.

Absolute marketing junk. You're better off buying factory blanks.
if all dimpled rotors do was give u cheese, then all those manufacturers making dimpled and cross drilled rotors have been making cheese since forever!!!
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      08-22-2009, 11:26 AM   #10
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      08-23-2009, 01:38 PM   #11
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I would avoid cross drilled holes because they introduce more areas that residual stresses and material flaws can result in fractures. Done right dimples and slots theoretically improve gas release at cost of slight reduction in surface area. Braking is huge for race cars. Some use complex rotor machining, some don't.

The aesthetic appeal is the link to high tech expensive caché. Sales of Brembos et al would be drastically lower if they did not have this distinctive high tech big $ look to them. Same reason Brembo offers their calipers in bright colors. M3s, Porsches, Ferraris, etc. have the 'look', so that can be worth emulating. I think they can look great if done right. In real world street driving I doubt I would notice much difference with slots or dimples. But I think they look cool and probably add a few $ to resale.
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      09-04-2009, 09:55 AM   #12
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Quote:
Originally Posted by stressdoc View Post
I would avoid cross drilled holes because they introduce more areas that residual stresses and material flaws can result in fractures. Done right dimples and slots theoretically improve gas release at cost of slight reduction in surface area. Braking is huge for race cars. Some use complex rotor machining, some don't.

The aesthetic appeal is the link to high tech expensive caché. Sales of Brembos et al would be drastically lower if they did not have this distinctive high tech big $ look to them. Same reason Brembo offers their calipers in bright colors. M3s, Porsches, Ferraris, etc. have the 'look', so that can be worth emulating. I think they can look great if done right. In real world street driving I doubt I would notice much difference with slots or dimples. But I think they look cool and probably add a few $ to resale.
It should not be omitted that slotted rotors also provide for better braking under rainy conditions, as the water film that tends to accumulate on the rotors flows off more efficiently than on the blank OEM rotors. People have complained very frequently about the braking behaviour of the previous 3 series (in particular E46 330i), and I also encountered the same problem (i.e. brakes only started to work almost one second after having touched the pedal, car started to veer in one direction while braking) with my previous Alpina B3. I can't begin to tell you how frightening it is when you step on the brakes at 200 km/h and nothing happens...for almost a second! It got very noticeably better after the installation of after market slotted rotors (I used ATE PowerDisc but which are not presently available for the E9x 335i).

I have not yet had the same problem with the 335i, at least not to the same degree, also due to the fact that it has this fancy automatic dry braking function (which apparently only works if the swipers are activated). However, some weeks ago when driving under heavy rain I also noticed a slight delay in braking response and a veer to one side when braking; in Germany a number of people have already reported the same problem with the same car, independently of the swipers (= dry braking) being activated or not.

I would therefore venture the guess that slotted rotors would also improve the braking behaviour of the car under wet conditions. As I'll be installing the EBC rotors in some weeks myself, I can report on this from my own experience then.

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      09-04-2009, 10:15 AM   #13
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Quote:
Originally Posted by The HACK View Post
"Dimples" or slots does nothing for a street application. All those dimples will do is act like cheese graters on your brake pads, reduce overall sweep area, and introduce noise while braking.

Absolute marketing junk. You're better off buying factory blanks.
Quote:
Originally Posted by ToadHollow View Post
LOL ..... ^^^^^ No noise, brake pads have no more signs of usage at this point than my OEM pads at time of replacement. The "sweep area" loss is so minimal that it makes no difference.

Dimpled, slotted or drilled rotors simply allow the rotor more effective cooling. The indentations on the rotor surface allow more air to flow between the rotor & brake pad surface. This also allows for less chance of brake fade with the proper brake pads in place.

I also have a set of rotors (different brand) that are slotted/dimpled in use with a set of the Cool Carbon brake pads. The rotors were installed before the pads and the stopping performance with the rotors in place was noticably better than OEM.

With the Cool Carbon pads installed the stopping performance between this setup & OEM is night and day.
Quote:
Originally Posted by Mr. 5 View Post
Will you give us your background so we can determine whether to take this comment and prove you wrong or either just completely ignore what you said?
I just did a review on my cheese graders.
http://www.e90post.com/forums/showthread.php?t=292297
I must have lots of mozzarella in my wheel wells.

I don't like the hack, he annoys me, which should lend more unbias to the fact I'm about to agree with him (at least on the dimples) The point of slotted and drilled rotors is to let escaping gases escape from the area between the rotor and pad itself. A dimple is not going to do this, or at the very least not as effectively. A slot or a hole will. And he is also correct that for most street applications they are almost 100% useless as you wont have any out gassing at those temps. However, some people make repeated stops from 150+ mph on the street, and they will play a role there.

None of the aforementioned designs are for cooling, at all, the only effect on cooling is the vanes themselves the airflow they receive from the center of the rotor and how effective their internal structure is, they receive no additional cooling from drills or slots, which actually only serve to decrease the maximum heat capacity of the rotor.

Slots do in fact increase brake wear over a flat rotor as well.

Also I can't tell if those rotors have straight vanes or curved vanes, but as far as I can tell your rotors are on backwards MR 5, the slots are supposed to contact the pad at the outer most radius FIRST and move in, not the other way around like yours are installed (assuming correct design). But before that you are supposed to install them by vane design (if curved) so that the vanes are curving toward the back of the car. Both these things are counter intuitive so tons of people put them on wrong (and even "engineers" design them wrong).
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      09-04-2009, 10:20 AM   #14
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Found something for you Mr. 5 that explains with pictures how to properly install rotors.

http://www.zeckhausen.com/how_to_pro...all_rotors.htm
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      09-04-2009, 11:04 AM   #15
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Quote:
Originally Posted by Mr. 5 View Post
Will you give us your background so we can determine whether to take this comment and prove you wrong or either just completely ignore what you said?
I just did a review on my cheese graders.
http://www.e90post.com/forums/showthread.php?t=292297
I must have lots of mozzarella in my wheel wells.
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?

p.s.: And if you believe all that b.s. I just listed, I've got a bridge in Brooklyn to sell you too.
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      09-04-2009, 11:09 AM   #16
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Quote:
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I don't like the hack, he annoys me...
Don't hate me because I am RIGHT. Hate me because I'm beautiful.
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      09-04-2009, 11:30 AM   #17
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Opinions / advice regarding these two-piece rotors by Stillen:
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      09-04-2009, 11:35 AM   #18
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opinion ( and I know it's not what you're after) : they look like ass.

And according to the rest of the thread, you'll only see any gain from them with high speed use. useless for normal street driving
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      09-04-2009, 11:39 AM   #19
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Quote:
Originally Posted by O-cha View Post
I don't like the hack, he annoys me, which should lend more unbias to the fact I'm about to agree with him (at least on the dimples) The point of slotted and drilled rotors is to let escaping gases escape from the area between the rotor and pad itself. A dimple is not going to do this, or at the very least not as effectively. A slot or a hole will. And he is also correct that for most street applications they are almost 100% useless as you wont have any out gassing at those temps. However, some people make repeated stops from 150+ mph on the street, and they will play a role there.

None of the aforementioned designs are for cooling, at all, the only effect on cooling is the vanes themselves the airflow they receive from the center of the rotor and how effective their internal structure is, they receive no additional cooling from drills or slots, which actually only serve to decrease the maximum heat capacity of the rotor.

Slots do in fact increase brake wear over a flat rotor as well.

Also I can't tell if those rotors have straight vanes or curved vanes, but as far as I can tell your rotors are on backwards MR 5, the slots are supposed to contact the pad at the outer most radius FIRST and move in, not the other way around like yours are installed (assuming correct design). But before that you are supposed to install them by vane design (if curved) so that the vanes are curving toward the back of the car. Both these things are counter intuitive so tons of people put them on wrong (and even "engineers" design them wrong).
Quote:
Originally Posted by O-cha View Post
Found something for you Mr. 5 that explains with pictures how to properly install rotors.

http://www.zeckhausen.com/how_to_pro...all_rotors.htm
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.
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      09-04-2009, 12:13 PM   #20
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Quote:
Originally Posted by 200Duece View Post
opinion ( and I know it's not what you're after) : they look like ass.

And according to the rest of the thread, you'll only see any gain from them with high speed use. useless for normal street driving
fwiw, the ones they (Stillen) have for 335 are black, not gold. Not that I really care much about looks. The hats are 6061 T6 aluminum, the discs have a pillar vane design. I would not pay the extra to get drilled rotors. Probably the biggest advantage of these rotors is they are about 3 lbs. lighter than OEM. In addition to the benefits from reduced unsprung weight, they also stay cooler.

Street use? What does any mod really do for street use. Not much. Not like they're going to save my life by reducing stopping distance, or the tiny improvement in handling response will help me avoid an accident. I have come face-to-face with this habit we call modding, and I recognize it for the pointless money trap that it is.

My strategy is to wait to mod until I am replacing parts that are worn out. 32k miles and I'm in the market for new brakes. I justify upgrades with more expensive parts by saving $ via DIY, but of course it boils down to emotion: it's my Bimmer we are talking about here!

But I would still love to hear what the Hack, Mr.5 and other knowledgeable sorts have to contribute.

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

Working our way towards a brake parts sticky here...
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      09-04-2009, 12:19 PM   #21
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Originally Posted by The HACK View Post

p.s.: And if you believe all that b.s. I just listed, I've got a bridge in Brooklyn to sell you too.
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      09-04-2009, 12:32 PM   #22
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