E46 BMW Social Directory E46 FAQ 3-Series Discussion Forums BMW Photo Gallery BMW 3-Series Technical Information E46 Fanatics - The Ultimate BMW Resource BMW Vendors General E46 Forum The Tire Rack's Tire Wheel Forum Forced Induction Forum The Off-Topic The E46 BMW Showroom For Sale, For Trade or Wanting to Buy

Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   E46Fanatics > Tuning & Tech > Suspension & Braking

Suspension & Braking
Have some questions about suspension or brake setups for your E46 BMW? Get all your answers here!

Reply
 
Thread Tools Search this Thread Rating: Thread Rating: 2 votes, 5.00 average. Display Modes
Old 03-01-2007, 04:54 AM   #1
freshprince2421
Registered User
 
Join Date: Jun 2004
Location: San Diego
Posts: 1,399
My Ride: 325ci
I need ROTORS: Slotted vs. Drilled vs. OEM ?????

Ok so it is time to get new rotors/pads and I have been researching what to purchase. I have read through quite a number of threads here but have yet to come to a conclusion. What exactly are the benefits of slotted or drilled rotors compared to OEM? Here are a couple tidbits of info I came across while searching:

Directly off of UUC's website...
"Slotting: there are many reasons to slot rotors. Primarily, slotting aids in removal of water and debris on the rotor surface, evacuation of hot pad "off gassing" vapor, and provides a visual wear indicator.

Details: These slots do not extend all the way to the edge of the rotor for a very specific reason; this maintains the structural integrity of the rotor. Other brands with slots all the way to the end have created "stress risers" where cracking may develop. No such problem exists with this design. Additionally, directional slotting enhances effectiveness.

NO DRILLING! Drilled holes in rotors often used for "show" are prone to cracking and catastrophic failure. The holes create stress risers which will lead to this sort of failure. Additionally, drilled holes do not improve cooling, rotary-vane rotors lose efficiency when drilled because cooling air does not not pass through the rotor circumferentially but is instead prematurely evacuated by the holes.. "


Hmmm if cross drilled rotors do no improve cooling and are prone to failure then why would any BBK use them?


Also here is more info found when scanning ebay (link below)...
"Brembo OE "blank" rotors offer better performance than Cross-drilled rotors. Cross-drilled rotors might look "cool", but what are they really doing for performance? Brake rotors were first "drilled" in the 40's and 50's because early brake pad materials gave off gasses when heated to racing temperatures, which is called "gassing out". These gasses then formed a thin layer between the brake pad face and the rotor, effectively lowering the coefficient of friction. The "cross drilled" holes were implemented to give the gasses a place to escape. Today's brake pad materials do not exhibit the same gassing out problems as these early (old) pads. Also, there are many companies that sell "cheap" cross-drilled and slotted rotors. They do this by purchasing Brembo blanks and having them cheaply altered by a third party. Doing this sacrifices the rotors structural integrity, and can be a huge safety risk. If you contact Brembo, they will not recognize these discs after they have been altered. These rotors are known to crack and warp very quickly. If you want the actual Brembo cross drilled and slotted rotors you will be paying much more. That's why these blanks are perfect; they perform better, do not tear through pads, are priced much lower, and are much safer."
http://cgi.ebay.com/ebaymotors/Bremb...87492957QQrdZ1

So right now I am deciding between the following rotors:

1. Stoptech Cross Drilled Rotors

2. Stoptech Slotted Rotors

3. Cross Drilled Brembos (stated above are most likely punched by a 3rd party)

4. UUC Slotted Rotors

5. OEM Rotors



I really like the look of the cross drilled rotors but do not want to purchase them at the risk of performance and safety. Hopefully someone can enlighten me. Rob maybe? Thanks in advance
__________________

Last edited by freshprince2421; 03-01-2007 at 05:48 AM.
freshprince2421 is offline   Reply With Quote
Ads by Google

Guests, get your FREE E46Fanatics.com membership to remove this ad.
Old 03-01-2007, 08:22 AM   #2
thesunfell
Registered User
 
Join Date: Feb 2007
Location: Florida
Posts: 746
My Ride: 330ci
nothing beats the guarantee of an oem part but after doing alot of research lately it seems like you should go with the uuc for an aftermarket part...i love thier "overkill" philosophy....
thesunfell is offline   Reply With Quote
Old 03-01-2007, 08:55 AM   #3
brosher
Registered User
 
Join Date: Jan 2007
Location: Albany, NY
Posts: 201
My Ride: 04 325XI
Unless you are on the track get regular rotors. I got some from napa for $25/each. I think the brand was trustop.
brosher is offline   Reply With Quote
Old 03-01-2007, 09:13 AM   #4
Nigma
Registered User
 
Join Date: Jan 2007
Location: Atlanta
Posts: 25
My Ride: 2000 323i
If you have to go with something "fancy" then go slotted, the general idea behind them is sound, while the driled are really just for show. They will wear your pad faster (think of a cheese grater). Personally im just a daily street driver so Iwent with the standard OEM rotors and have been happy. But it all comes down to what makes you happy, if you want to have a nice set of good looking rotors then get the drilled or slotted (slotted being my choice of the two).


Nigma
Nigma is offline   Reply With Quote
Old 03-01-2007, 09:36 AM   #5
Rob Levinson * UUC Motorwerks
UUC Motorwerks, *******
 
Rob Levinson * UUC Motorwerks's Avatar
 
Join Date: Dec 1969
Location: GA
Posts: 3,940
My Ride: 7s, M5s, M3s, others
Quote:
Originally Posted by freshprince2421 View Post

NO DRILLING! Drilled holes in rotors often used for "show" are prone to cracking and catastrophic failure. The holes create stress risers which will lead to this sort of failure. Additionally, drilled holes do not improve cooling, rotary-vane rotors lose efficiency when drilled because cooling air does not not pass through the rotor circumferentially but is instead prematurely evacuated by the holes.. "[/COLOR]

Hmmm if cross drilled rotors do no improve cooling and are prone to failure then why would any BBK use them?
Excellent question!

The rotors we use in the big brake kit are genuine BMW Motorsport rotors, which are apparently cast-perforated, not actually drilled.

The difference is that the holes are cast into the rotor, so the metallic grain structure (and therefore the strength) is not compromised as with conventional drilling.

Please note that we are in the process of updating our website pricing on brake rotors.

I think that you will find our new Gen2 black rotor regular pricing is better than "group buy" pricing for other brands.


New package options include SS lines, pads, fluid, at pricing below regular single-item pricing.

Please see: http://www.uucmotorwerks.com/rotors/ and click on your application for options. Please note - not all applications updated yet, if your listing does not show all options, please call us for pricing!

- Rob
__________________
- Rob Levinson * UUC Motorwerks * 678-679-5360 * uucmotorwerks.com

BIG BRAKE KIT HEADQUARTERS!

ALL CURRENT UUC SPECIALS:
-[ CLICK HERE ]
Rob Levinson * UUC Motorwerks is offline   Reply With Quote
Old 03-01-2007, 10:00 AM   #6
drcollie
Registered User
 
Join Date: Nov 2006
Location: Fairfax VA
Posts: 120
My Ride: E90, E46, 1200GS, X5
Remember too, that when you see all those race cars sporting drilled rotors, its because they consider it a good track weekend if they last FRI, SAT, SUN. Rotors and brake pads are disposable items to a race team and they include that in their track weekend budget.

The typical street driver wants longevity from their rotors, a long-lasting pad that is quiet and doesn't eat the rotors up quickly, and brakes that don't squeal or rattle. This is what BMW gives you in OEM products.

Rob@UUC and I go wayyyyyyy back, over 10 years playing with BMW's, don't we buddy? The only 'holed' rotors that we'd run on our cars are the ones that are cast in the formation process (such as what comes standard from Porsche AG).

If you want the look of a more 'racy' rotor, then go slotted from UUC.

Personally, I run OEM on all three of my BMW's.
drcollie is offline   Reply With Quote
Old 03-01-2007, 10:06 AM   #7
Rob Levinson * UUC Motorwerks
UUC Motorwerks, *******
 
Rob Levinson * UUC Motorwerks's Avatar
 
Join Date: Dec 1969
Location: GA
Posts: 3,940
My Ride: 7s, M5s, M3s, others
Quote:
Originally Posted by drcollie View Post
Rob@UUC and I go wayyyyyyy back, over 10 years playing with BMW's, don't we buddy?
The only time in my entire life that I actually got nauseous in a car was with you in your then-new '95 M3 at a NCC auto-x. You NCC boys know how to play!

- Rob
Rob Levinson * UUC Motorwerks is offline   Reply With Quote
Old 03-01-2007, 10:22 AM   #8
drcollie
Registered User
 
Join Date: Nov 2006
Location: Fairfax VA
Posts: 120
My Ride: E90, E46, 1200GS, X5
Quote:
Originally Posted by Rob Levinson * UUC Motorwerks View Post
The only time in my entire life that I actually got nauseous in a car was with you in your then-new '95 M3 at a NCC auto-x. You NCC boys know how to play!

- Rob
But you didn't barf, so it was all good....

I miss that car!
drcollie is offline   Reply With Quote
Old 03-01-2007, 10:29 AM   #9
imetis
Registered User
 
Join Date: Oct 2006
Location: Lansing, MI
Posts: 90
My Ride: 2003 325i
Drilled or slotted rotors will chew through pads faster, and any performance improvement is sketchy at best. My opinion is that the best performance is found with blank rotors and high performance pads.

That said, I have run the cheap drilled rotors with Axxis Ultimate pads before, and had great braking performance and no warping or cracking issues. As said above though, pads wore out much faster, and the rotors cannot be turned once they are grooved. It looked nice, but I'll stick with OEM rotors from here.
imetis is offline   Reply With Quote
Old 03-01-2007, 10:40 AM   #10
GunMoto
Registered User
 
Join Date: Dec 1969
Location: OC/SD, CA
Posts: 3,529
My Ride: EG8 | E46 | W211
Send a message via AIM to GunMoto
You should have no issues with Brembo blanks if your car is a street driven daily driver.
__________________
GunMoto is offline   Reply With Quote
Old 03-01-2007, 10:48 AM   #11
Stevo759
Registered User
 
Join Date: May 2004
Location: Irvine, CA
Posts: 526
My Ride: M5
Send a message via AIM to Stevo759
i found a huge difference when I got slotted rotors. I got "Frozen Rotors" with ceramic pads and not only did I notice a performance difference, but with the ceramic pads brake dust is almost obsolete
__________________
2001 Carbon Black BMW///M5 ............................2001 Turbo Honda S2000
Stevo759 is offline   Reply With Quote
Old 03-01-2007, 10:52 AM   #12
CroBmw
Registered User
 
Join Date: Aug 2004
Location: home
Posts: 2,072
My Ride: skates
If Drilled rotors are not good why would Mercedes have them on almost every car?
CroBmw is offline   Reply With Quote
Old 03-01-2007, 10:54 AM   #13
Rob Levinson * UUC Motorwerks
UUC Motorwerks, *******
 
Rob Levinson * UUC Motorwerks's Avatar
 
Join Date: Dec 1969
Location: GA
Posts: 3,940
My Ride: 7s, M5s, M3s, others
Quote:
Originally Posted by imetis View Post
Drilled or slotted rotors will chew through pads faster, and any performance improvement is sketchy at best. My opinion is that the best performance is found with blank rotors and high performance pads.
Not quite. "Performance" is more than just 60-0.

In real-world use, slotted rotors provide additional benefits in water (rain) evacuation from the surface, and pad freshening to reduce glazing/squealing.

Additionally, they serve as a useful visual wear indicator... when the slots are gone, time to replace rotors!

Quote:
That said, I have run the cheap drilled rotors with Axxis Ultimate pads before, and had great braking performance and no warping or cracking issues.
Then you're not using them hard.

Axxis pads, despite the marketing, are not "enthusiast" pads. They are very hard pads, and we've seen many instances of premature wear and surface cracking.

We test as many pads as possible so that we can offer our customers the best choices for their needs. I wish we found Axxis suitable, great profit margin!

- Rob
Rob Levinson * UUC Motorwerks is offline   Reply With Quote
Old 03-01-2007, 10:54 AM   #14
hummer
Registered User
 
Join Date: Apr 2003
Location: Haverhill, MA
Posts: 3,321
My Ride: 2001 330CI
My motto is don't buy more than you need. So, for the street it's plain rotors and good pads like Axxis metal masters. Fashion fads are another thing altogether. Just don't confuse fashion with function! I do have ATE slotted disks on my wifes Audi because she's a lite braker and the slots help even out the wear. Which brings up an interesting point on wheel size. Anything over 18" and less that 45 aspect ratio is the same thing=fashion fad. If the fashion fad is race car like drilled rotors why isn't the fashion fad Forlmula 1 like small wheels and big tires? There's no predicting those fashion fads!
hummer is offline   Reply With Quote
Old 03-01-2007, 11:06 AM   #15
Rob Levinson * UUC Motorwerks
UUC Motorwerks, *******
 
Rob Levinson * UUC Motorwerks's Avatar
 
Join Date: Dec 1969
Location: GA
Posts: 3,940
My Ride: 7s, M5s, M3s, others
Quote:
Originally Posted by CroBmw View Post
If Drilled rotors are not good why would Mercedes have them on almost every car?
Mercedes had a service campaign (silent recall) on their drilled rotors for cracking soon after they came out.

Newest ones are made differently, similar cast-perforated (not drilled) as I described above.

They use them because that's what customers ask for. No performance gain. Customers ask for purple paint, too, and any auto maker is happy to oblige to make a sale.

- Rob
Rob Levinson * UUC Motorwerks is offline   Reply With Quote
Old 03-01-2007, 11:20 AM   #16
FTLAUDM3
Registered User
 
Join Date: Jan 2006
Location: Ft. Lauderdale
Posts: 1,491
My Ride: M3, Z4
I believe all the hype about drilled rotors...but I went with a cross drilled/slotted combo from IRotors.com anyways and completely satisfied so far.

After 8 months they are still in great condition. Can barely even tell that they have worn at all. I would have went with a Brembo rotor, but unfortunately they don't make em for the E46 M3.

I still find it hard to believe that the drilled are dangerous. Mercedes, Audi, Porsche, BMW, and any sports car use em. After reading this thread I guess they are all done the proper way though. Every BBK (Brembo, Stoptech, Wilwood, Rotora, etc) all use em. The question is how are they made....
__________________
FTLAUDM3 is online now   Reply With Quote
Old 03-01-2007, 11:30 AM   #17
Rob Levinson * UUC Motorwerks
UUC Motorwerks, *******
 
Rob Levinson * UUC Motorwerks's Avatar
 
Join Date: Dec 1969
Location: GA
Posts: 3,940
My Ride: 7s, M5s, M3s, others
Quote:
Originally Posted by FTLAUDM3 View Post
I still find it hard to believe that the drilled are dangerous. Mercedes, Audi, Porsche, BMW, and any sports car use em. After reading this thread I guess they are all done the proper way though. Every BBK (Brembo, Stoptech, Wilwood, Rotora, etc) all use em. The question is how are they made....
Marketing is amazing in what it says and what it does not say so clearly...

Stoptech very specifically does not recommend their drilled rotors for track or race use.

Please read what I wrote about about cast-perforated versus drilled rotors. An aftermarket drilled rotor is definitely not the same as the OE rotors.

- Rob
Rob Levinson * UUC Motorwerks is offline   Reply With Quote
Old 03-01-2007, 11:48 AM   #18
jpr
Registered User
 
Join Date: Aug 2005
Location: San Diego, CA
Posts: 3,005
My Ride: '99 323i
What exactly does "cast-perforated" mean?
Are the holes cast clear through entire, as a pilot, as a dimple, or something else?
What, if any, machining takes place on the holes after casting?
jpr is offline   Reply With Quote
Old 03-01-2007, 11:55 AM   #19
Rob Levinson * UUC Motorwerks
UUC Motorwerks, *******
 
Rob Levinson * UUC Motorwerks's Avatar
 
Join Date: Dec 1969
Location: GA
Posts: 3,940
My Ride: 7s, M5s, M3s, others
Quote:
Originally Posted by jpr View Post
What exactly does "cast-perforated" mean?
Are the holes cast clear through entire, as a pilot, as a dimple, or something else?
What, if any, machining takes place on the holes after casting?
...

Quote:
Originally Posted by Rob Levinson * UUC Motorwerks View Post
The rotors we use in the big brake kit are genuine BMW Motorsport rotors, which are apparently cast-perforated, not actually drilled.

The difference is that the holes are cast into the rotor, so the metallic grain structure (and therefore the strength) is not compromised as with conventional drilling.
Holes are holes - all the way through. Not dimples.

Normal post-casting cleanup maching takes place, no different than any other rotor... the rotor face, edges, inner and outer hub faces, and casting flash within the holes. When you look at a rotor, every surface that is not rough has been machined.

- Rob
Rob Levinson * UUC Motorwerks is offline   Reply With Quote
Old 03-01-2007, 12:08 PM   #20
colombacho
Registered User
 
Join Date: Jul 2006
Location: denver
Posts: 426
My Ride: 325i
Well, if you want the rotors just for looks, and not performace go for it. Dont think you will be cracking them, unless you drive your car hard. I got the brembo sloted/drilled, have not given me any trouble. But for performace or auto X i would go with just slotted.
colombacho is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Censor is ON





All times are GMT -5. The time now is 02:19 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
(c) 1999 - 2011 performanceIX Inc - privacy policy - terms of use