Pandora Car Alarm System
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read

Go Back   BMW M3 and BMW M4 Forum > BMW F80 M3 / F82 M4 Technical Topics > Track / Autocross / Dragstrip / Driving Techniques

Post Reply
 
Thread Tools Search this Thread
      09-15-2019, 03:50 PM   #1
David0ff
Combined Applications Group
David0ff's Avatar
Canada
1055
Rep
680
Posts

Drives: Lada Scrapus Trofeo R
Join Date: Jan 2014
Location: Classified

iTrader: (1)

Hey Guy
This is my first set of rotors, original, car has 15k Kms and around 5000kms on the track
Pads are HP Plus all corners

I took several shots of my front driver rotor but passenger is the same.

I read somewhere that rotors need to be changed if any of 3 conditions are met:
- cracks link 2 holes (not my case)
- cracks exit rotor surface , in/out ( not yet)
- most of the cracks are longer than 13mm (getting there)

What's the status of these rotors?

Thx
Attached Images
       
__________________
/////////
Appreciate 0
      09-15-2019, 06:06 PM   #2
Suds
/M Enthusiast
Suds's Avatar
United_States
1596
Rep
1,617
Posts

Drives: Responsiblish
Join Date: Aug 2010
Location: Lone Star State

iTrader: (1)

I have been told my rotors have two or three track weekends left.
Attached Images
 
__________________
2019 M2 Comp, Alpine White, DCT, track car build, 1/2 cage, AP Racing Brakes & Nitron Coilovers, BM3 Stage 1 93 Oct.
2018 Porsche Cayman GTS, Night Blue Metalic, PDK, COBB tuned 93 Oct.
2004 Audi A4 Avant USP 6mt, RS4 clutch, built motor, Garrett GT3071r "Big Ass Turbo" Motoza Tune
Appreciate 1
David0ff1055.00
      09-15-2019, 08:14 PM   #3
CRRobert
Private First Class
55
Rep
193
Posts

Drives: 18 Avus Blue ZCP M3
Join Date: Dec 2018
Location: Denver, CO

iTrader: (0)

So when either of you replace your rotors, are you going OEM, aftermarket rotors, or BBK? Try to get replaced under warranty? Curious in that I figured I will have to at some point.
Appreciate 0
      09-15-2019, 08:32 PM   #4
Suds
/M Enthusiast
Suds's Avatar
United_States
1596
Rep
1,617
Posts

Drives: Responsiblish
Join Date: Aug 2010
Location: Lone Star State

iTrader: (1)

I will go OEM if I am ready to move on from the M4, otherwise I will go with a non OEM slotted rotor.

I usually track a car for a year or two, then I will move on. Presently I love the way my M4 feels.
__________________
2019 M2 Comp, Alpine White, DCT, track car build, 1/2 cage, AP Racing Brakes & Nitron Coilovers, BM3 Stage 1 93 Oct.
2018 Porsche Cayman GTS, Night Blue Metalic, PDK, COBB tuned 93 Oct.
2004 Audi A4 Avant USP 6mt, RS4 clutch, built motor, Garrett GT3071r "Big Ass Turbo" Motoza Tune
Appreciate 1
David0ff1055.00
      09-15-2019, 09:43 PM   #5
David0ff
Combined Applications Group
David0ff's Avatar
Canada
1055
Rep
680
Posts

Drives: Lada Scrapus Trofeo R
Join Date: Jan 2014
Location: Classified

iTrader: (1)

I will also do either oem or oem equivalent replacement depending on what's available, not looking for BBK right now

Not sure my warranty covers this
2018 M4 lease Canadian Car
__________________
/////////
Appreciate 0
      09-16-2019, 04:11 AM   #6
CanAutM3
General
CanAutM3's Avatar
Canada
21105
Rep
20,741
Posts

Drives: 2021 911 turbo
Join Date: Jan 2012
Location: Montreal

iTrader: (1)

Garage List
These rotors almost look like new . The replacement conditions you specify in your OP are correct as long as you meet the minimum thickness. You are good for way more than 2 more track days .

From the BMW M3 / M4 Brake Systems: Deep Dive and Interview :

Quote:
Why is it that with perforated brake discs in particular, you occasionally see slight cracks?

Cracks form in particular wherever relatively cold discs are suddenly subjected to a large load. The cracks that occur are limited to the surface areas. For instance, if you have been driving your car fully laden on the motorway for an extended period without braking and then you are suddenly called upon to perform an emergency braking manoeuvre, the brake disc will become very hot in a very short space of time – in such a case, the temperature can increase from around 20 degrees to 450 degrees. If the brake disc is required to perform in this manner several times in rapid succession, it is quite possible for surface cracks to form in the cast material of the friction ring – especially in the area around the perforation holes. In sports cars, cracks like these are, more than anything, a sign that they are being subjected to the use for which they were designed, and they have no negative effect on the service life of the brake disc or its braking performance.
__________________
Porsche 911 turbo 2021 992 GT Silver

Previous cars: M4cs 2019 F82 Limerock Grey / M4 2015 F82 Silverstone / M3 2008 E92 Silverstone / M3 2002 E46 Carbon Black

Last edited by CanAutM3; 09-16-2019 at 06:30 AM..
Appreciate 1
David0ff1055.00
      09-16-2019, 04:24 AM   #7
robbo mcs
First Lieutenant
Australia
142
Rep
318
Posts

Drives: F82 M4 and others
Join Date: Apr 2014
Location: Sydney

iTrader: (0)

What is the thickness of the rotors? Have you measured it? If they are under the minimum thickness, they need replacing.

5000kms of track time is a lot! Are you sure it is that much? If that is truly the case, I would be amazed if the original rotors were still ok.
Appreciate 1
      09-16-2019, 07:06 AM   #8
David0ff
Combined Applications Group
David0ff's Avatar
Canada
1055
Rep
680
Posts

Drives: Lada Scrapus Trofeo R
Join Date: Jan 2014
Location: Classified

iTrader: (1)

Quote:
Originally Posted by CanAutM3 View Post
These rotors almost look like new . The replacement conditions you specify in your OP are correct as long as you meet the minimum thickness. You are good for way more than 2 more track days .

From the BMW M3 / M4 Brake Systems: Deep Dive and Interview :

Quote:
Why is it that with perforated brake discs in particular, you occasionally see slight cracks?

Cracks form in particular wherever relatively cold discs are suddenly subjected to a large load. The cracks that occur are limited to the surface areas. For instance, if you have been driving your car fully laden on the motorway for an extended period without braking and then you are suddenly called upon to perform an emergency braking manoeuvre, the brake disc will become very hot in a very short space of time – in such a case, the temperature can increase from around 20 degrees to 450 degrees. If the brake disc is required to perform in this manner several times in rapid succession, it is quite possible for surface cracks to form in the cast material of the friction ring – especially in the area around the perforation holes. In sports cars, cracks like these are, more than anything, a sign that they are being subjected to the use for which they were designed, and they have no negative effect on the service life of the brake disc or its braking performance.
Awesome thank you

When's the next tremblant?
__________________
/////////
Appreciate 0
      09-16-2019, 07:12 AM   #9
David0ff
Combined Applications Group
David0ff's Avatar
Canada
1055
Rep
680
Posts

Drives: Lada Scrapus Trofeo R
Join Date: Jan 2014
Location: Classified

iTrader: (1)

Quote:
Originally Posted by robbo mcs View Post
What is the thickness of the rotors? Have you measured it? If they are under the minimum thickness, they need replacing.

5000kms of track time is a lot! Are you sure it is that much? If that is truly the case, I would be amazed if the original rotors were still ok.
I will measure it but it's well above min,
Also I don't run my pads much below 40% so min thickness is not something I'm concerned about. As I understand it min thickness is something to worry about if you have rotor at min thick and Pads worn to the plate then you risk having your piston fall off.

I think cracks will kill mine before min thickness achievement unlock.

Also the local tracks I go to are not that high speed, max deceleration is 165kmh -> ~80

But I do go a lot haha and do around 100-120 kms a day, I go ~2-3 times a week

I will check min and update
__________________
/////////
Appreciate 0
      09-16-2019, 10:33 AM   #10
OhioRiderAaron
Captain
United_States
368
Rep
697
Posts

Drives: 2016 BMW M3 ZCP
Join Date: Apr 2014
Location: Columbus, OH

iTrader: (0)

You may want to consider DIY brake ducts for the next set of rotors.

When my rotors got to that point I started looking at them after every session just in case. However, I've seen plenty of older Porsche's run them until there's hundreds of cracks across the rotor face.
__________________

ZCP - Daily Driven Trackster ~ Gone but not Forgotten
1LE - Track Rubber & Garage Dust Collector
Appreciate 0
      09-16-2019, 05:45 PM   #11
Ex_Stig
Colonel
Ex_Stig's Avatar
2563
Rep
2,674
Posts

Drives: '24 X7 M60i
Join Date: Jan 2014
Location: Scottsdale, AZ

iTrader: (0)

Garage List
2024 BMW X7 M60  [10.00]
Quote:
Originally Posted by OhioRiderAaron View Post
You may want to consider DIY brake ducts for the next set of rotors.

When my rotors got to that point I started looking at them after every session just in case. However, I've seen plenty of older Porsche's run them until there's hundreds of cracks across the rotor face.
I'd love to put some brake ducts in, but where are people running the hoses? I haven't found a good location.
__________________
Ex Stig

'25 M5 Touring (on the list, first slot)
'24 X7 M60i
'22 M5 CS - (sold)
Appreciate 0
      09-16-2019, 06:15 PM   #12
CanAutM3
General
CanAutM3's Avatar
Canada
21105
Rep
20,741
Posts

Drives: 2021 911 turbo
Join Date: Jan 2012
Location: Montreal

iTrader: (1)

Garage List
Quote:
Originally Posted by David0ff View Post
Awesome thank you

When's the next tremblant?
September 25th. Last day of the season
__________________
Porsche 911 turbo 2021 992 GT Silver

Previous cars: M4cs 2019 F82 Limerock Grey / M4 2015 F82 Silverstone / M3 2008 E92 Silverstone / M3 2002 E46 Carbon Black
Appreciate 1
David0ff1055.00
      09-16-2019, 08:03 PM   #13
MaynardZed
Lieutenant Colonel
MaynardZed's Avatar
United_States
1231
Rep
1,789
Posts

Drives: wife crazy
Join Date: Jul 2014
Location: Phoenix

iTrader: (0)

Garage List
Quote:
Originally Posted by CanAutM3 View Post
September 25th. Last day of the season
Lots of Canadians buying or renting winter homes here in Phoenix Our season is just starting to ramp up.
__________________
Road course laptimes for BMW M4 2015 6MT
WHP East Track: 1:04.880, Arizona Motorsports Park: 1:54.352
Road course laptimes for Porsche 911 991.1 GTS 7MT
WHP East Track: 1:02.770, Arizona Motorsports Park: 1:48.889
Appreciate 1
CanAutM321104.50
      09-16-2019, 08:08 PM   #14
CanAutM3
General
CanAutM3's Avatar
Canada
21105
Rep
20,741
Posts

Drives: 2021 911 turbo
Join Date: Jan 2012
Location: Montreal

iTrader: (1)

Garage List
Quote:
Originally Posted by MaynardZed View Post
Lots of Canadians buying or renting winter homes here in Phoenix Our season is just starting to ramp up.
I can't complain though, I've had a pretty decent season this year with 24 track days
__________________
Porsche 911 turbo 2021 992 GT Silver

Previous cars: M4cs 2019 F82 Limerock Grey / M4 2015 F82 Silverstone / M3 2008 E92 Silverstone / M3 2002 E46 Carbon Black

Last edited by CanAutM3; 09-17-2019 at 08:49 PM..
Appreciate 3
David0ff1055.00
Gomeler500.00
MaynardZed1231.00
      09-17-2019, 05:18 PM   #15
nicknaz
Lieutenant General
nicknaz's Avatar
3183
Rep
10,509
Posts

Drives: C6Z
Join Date: May 2008
Location: NorCal

iTrader: (0)

Quote:
Originally Posted by CanAutM3 View Post
I can't complain though, I've had a pretty decent decent season this year with 24 track days
way to max out the short northeast season.
Appreciate 1
CanAutM321104.50
      09-25-2019, 08:01 PM   #16
Suds
/M Enthusiast
Suds's Avatar
United_States
1596
Rep
1,617
Posts

Drives: Responsiblish
Join Date: Aug 2010
Location: Lone Star State

iTrader: (1)

I added 3 days at COTA last weekend, about 5-1/2 track hours.
These Beaches are still holding on.
This is with PFC08 pads.

46k total miles on the rotors.
Attached Images
 
__________________
2019 M2 Comp, Alpine White, DCT, track car build, 1/2 cage, AP Racing Brakes & Nitron Coilovers, BM3 Stage 1 93 Oct.
2018 Porsche Cayman GTS, Night Blue Metalic, PDK, COBB tuned 93 Oct.
2004 Audi A4 Avant USP 6mt, RS4 clutch, built motor, Garrett GT3071r "Big Ass Turbo" Motoza Tune
Appreciate 1
David0ff1055.00
      09-25-2019, 09:02 PM   #17
David0ff
Combined Applications Group
David0ff's Avatar
Canada
1055
Rep
680
Posts

Drives: Lada Scrapus Trofeo R
Join Date: Jan 2014
Location: Classified

iTrader: (1)

Quote:
Originally Posted by Suds View Post
I added 3 days at COTA last weekend, about 5-1/2 track hours.
These Beaches are still holding on.
This is with PFC08 pads.

46k total miles on the rotors.
Looking good!

So I got around measuring mine when changing pads/fluid this weekend
Both fronts are above 30mm thick so I guess they still have some life left
__________________
/////////
Appreciate 0
      09-25-2019, 09:17 PM   #18
Suds
/M Enthusiast
Suds's Avatar
United_States
1596
Rep
1,617
Posts

Drives: Responsiblish
Join Date: Aug 2010
Location: Lone Star State

iTrader: (1)

We all prefer to stay on the conservative side of oh shit!
We spend good money on track time and we don’t want to go home early with broke stuff.
__________________
2019 M2 Comp, Alpine White, DCT, track car build, 1/2 cage, AP Racing Brakes & Nitron Coilovers, BM3 Stage 1 93 Oct.
2018 Porsche Cayman GTS, Night Blue Metalic, PDK, COBB tuned 93 Oct.
2004 Audi A4 Avant USP 6mt, RS4 clutch, built motor, Garrett GT3071r "Big Ass Turbo" Motoza Tune
Appreciate 1
David0ff1055.00
      09-26-2019, 10:25 PM   #19
MyFragileHalogen
Captain
449
Rep
992
Posts

Drives: '16 M4 6MT
Join Date: May 2013
Location: OR

iTrader: (0)

I heard until a crack around a hole extends all the way to outer or inner edge they are good to use. I learned from experience that it's not a good idea to run it till it gets too thin which caused excessive pad wear due to too much heat.

I've just got these two piece rotors after waiting 3 weeks and blowing up the whole last month of the season.
Attached Images
 
Appreciate 1
David0ff1055.00
      09-26-2019, 11:27 PM   #20
David0ff
Combined Applications Group
David0ff's Avatar
Canada
1055
Rep
680
Posts

Drives: Lada Scrapus Trofeo R
Join Date: Jan 2014
Location: Classified

iTrader: (1)

Quote:
Originally Posted by MyFragileHalogen View Post
I heard until a crack around a hole extends all the way to outer or inner edge they are good to use. I learned from experience that it's not a good idea to run it till it gets too thin which caused excessive pad wear due to too much heat.

I've just got these two piece rotors after waiting 3 weeks and blowing up the whole last month of the season.
What rotors are those?
__________________
/////////
Appreciate 0
      09-27-2019, 12:15 AM   #21
MyFragileHalogen
Captain
449
Rep
992
Posts

Drives: '16 M4 6MT
Join Date: May 2013
Location: OR

iTrader: (0)

Quote:
Originally Posted by David0ff View Post
What rotors are those?
made by a company called racingbrake; they claim that their design has best of both world in slotted + drilled for track use. OEM rotors shipped box was 55lbs which I returned. These were 45lb in the shipped box.
Appreciate 0
      09-27-2019, 07:26 AM   #22
David0ff
Combined Applications Group
David0ff's Avatar
Canada
1055
Rep
680
Posts

Drives: Lada Scrapus Trofeo R
Join Date: Jan 2014
Location: Classified

iTrader: (1)

Quote:
Originally Posted by MyFragileHalogen View Post
Quote:
Originally Posted by David0ff View Post
What rotors are those?
made by a company called racingbrake; they claim that their design has best of both world in slotted + drilled for track use. OEM rotors shipped box was 55lbs which I returned. These were 45lb in the shipped box.
Thx!

Curious to see how they hold up and perform in the heat of battle
__________________
/////////
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 08:24 AM.




f80post
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