ZPOST
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   ZPOST > BMW Z4 Technical Talk > Suspension and Braking Chat
  TireRack

SUPPORT ZPOST BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER, THANKS!
Post Reply
 
Thread Tools Search this Thread
      06-22-2022, 11:55 PM   #1
Reborn_
Lieutenant
292
Rep
408
Posts

Drives: 2007 BMW Z4MC
Join Date: Dec 2014
Location: SoCal

iTrader: (7)

What's the Deal with the "Grooves" in Z4M Rotors

I had noticed these "grooves" in my rotors before, but never thought too much of it. I'm in the middle of replacing my original brakes with oem bmw rotors/pads and noticed something - the replacement rotors have grooves that span very little of the diameter compared to my original ones (see pics). So does anyone know what the design intent of these grooves are, and why bmw would change the design over time? My car is MY2007. More a curiosity than anything. Thanks in advance!
Attached Images
  
Appreciate 0
      06-23-2022, 12:20 AM   #2
XMetal
Colonel
XMetal's Avatar
United_States
1097
Rep
2,846
Posts

Drives: Anything
Join Date: Apr 2010
Location: SoCal

iTrader: (0)

Garage List
2008 Z4M Coupe  [10.00]
2018 Audi S3  [0.00]
2004 X5  [8.50]
If you're referring to the "grooves" in the center venting vanes, I believed it's for balancing the rotor. It's a method for them to remove materials in order to properly balance it. Each rotor should be slightly different, if you look closely.
__________________

Last edited by XMetal; 06-23-2022 at 12:36 AM..
Appreciate 3
wdb4673.00
Reborn_292.00
Coi287.50
      06-23-2022, 12:28 AM   #3
Reborn_
Lieutenant
292
Rep
408
Posts

Drives: 2007 BMW Z4MC
Join Date: Dec 2014
Location: SoCal

iTrader: (7)

Ah, interesting. Yes, in the center venting area. The new ones have material removed too, just for roughly 10 degrees of the diameter. My originals are like 120 degrees. It’s a bad pic - should have snapped one of the other side that’s not on the car yet.
Appreciate 0
      06-23-2022, 12:39 AM   #4
XMetal
Colonel
XMetal's Avatar
United_States
1097
Rep
2,846
Posts

Drives: Anything
Join Date: Apr 2010
Location: SoCal

iTrader: (0)

Garage List
2008 Z4M Coupe  [10.00]
2018 Audi S3  [0.00]
2004 X5  [8.50]
Our Audi's rotors have similar grooves, but runs shorter (only about 3 to 4 inches long) compared to what's currently on the Z4. I'm currently running Zimmermann front rotors on the Z4 and it has similar groove as the OE rotors that it replaced...similar to your old rotor pictured in the original post.
__________________
Appreciate 1
Reborn_292.00
      06-23-2022, 07:57 AM   #5
wdb
dances with roads
wdb's Avatar
4673
Rep
4,090
Posts

Drives: '07 E86, '02 996, '95 Seven
Join Date: Jul 2015
Location: the perimeter

iTrader: (4)

Quote:
Originally Posted by XMetal View Post
If you're referring to the "grooves" in the center venting vanes, I believed it's for balancing the rotor. It's a method for them to remove materials in order to properly balance it. Each rotor should be slightly different, if you look closely.
Makes sense.

Appreciate 3
Reborn_292.00
XMetal1096.50
racerbruce3848.50
      06-23-2022, 08:18 AM   #6
Reborn_
Lieutenant
292
Rep
408
Posts

Drives: 2007 BMW Z4MC
Join Date: Dec 2014
Location: SoCal

iTrader: (7)

This is great, thanks guys. Since I’ve got 8 rotors, I’ll pay attention and post up how much they all differ if anyone is curious. Will take me a bit more time though - not sure when I’ll finish the job.
Appreciate 0
      06-30-2022, 09:39 AM   #7
Reborn_
Lieutenant
292
Rep
408
Posts

Drives: 2007 BMW Z4MC
Join Date: Dec 2014
Location: SoCal

iTrader: (7)

Ok so wrapped the job up. Basically all 4 fronts had about a 40 degree cutout. The old rears had about a 120 degree cut out and the new ones had a 10 degree cutout. It’s probably the case that each manufacturing lot will have similar cutouts.
Appreciate 1
XMetal1096.50
      07-08-2022, 01:04 PM   #8
Rian_3385
Banned
-3
Rep
17
Posts

Drives: M8
Join Date: Jul 2022
Location: California

iTrader: (0)

40 fronts with 40 degree each
Appreciate 0
      07-08-2022, 01:06 PM   #9
Rian_3385
Banned
-3
Rep
17
Posts

Drives: M8
Join Date: Jul 2022
Location: California

iTrader: (0)

40 fronts for 40 degrees each
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off



All times are GMT -5. The time now is 09:29 PM.




zpost
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST