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      01-17-2020, 09:00 AM   #1
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Aftermarket rotors

My drilled front rotors are starting to crack and wanted to replace them with slotted rotors when they go. Does anyone make slotted rotors to work with OEM non competition calipers?
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      01-17-2020, 10:12 AM   #2
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Here's one source:

https://f87.bimmerpost.com/forums/sh....php?t=1363714
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      01-17-2020, 10:36 AM   #3
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OE is the most affordable. HPA shop stocks Alcon and stop tech but you’re looking at $1k/axle
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      01-17-2020, 10:40 AM   #4
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Heres 2 more

Alcon

https://f80.bimmerpost.com/forums/sh....php?t=1474110

Girodisc + others in this thread

https://f87.bimmerpost.com/forums/sh...php?p=23104206
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      01-17-2020, 10:42 AM   #5
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2k for the giro set - jesus - id just get a BBK at that point
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      01-17-2020, 03:09 PM   #6
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I have been using Stoptech front rotors, they are 2 piece, lighter, push more air, last longer and are about the same price as OEM. One strange benefit is that when I leave on my PFC08 pads they make a lot less noise than factory rotors.
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      01-17-2020, 03:39 PM   #7
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Thanks guys. I think I will be leaning Stoptech
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      01-17-2020, 05:08 PM   #8
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Quote:
Originally Posted by Twt View Post
I have been using Stoptech front rotors, they are 2 piece, lighter, push more air, last longer and are about the same price as OEM. One strange benefit is that when I leave on my PFC08 pads they make a lot less noise than factory rotors.
Where are you getting that price? OE is around $500-$600/axle. The stop techs are $600 each
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      01-17-2020, 06:38 PM   #9
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Have you considered a warranty claim? Cracking is not 'wear and tear'...
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      01-17-2020, 07:32 PM   #10
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Quote:
Originally Posted by M Fifty View Post
Have you considered a warranty claim? Cracking is not 'wear and tear'...
It is if you track and are getting a lot of heat into the rotor. They are hairline cracks and a common issue with drilled rotors. Slotted rotors are not prone to the same issues as drilled and are preferred for track use. Manufacturers just use drilled because they look cool.
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      01-17-2020, 07:49 PM   #11
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And at the track the holes fill up with pad material so the holes are completely useless anyway
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      01-18-2020, 06:39 AM   #12
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Quote:
Originally Posted by BeastieBombRacing View Post
Where are you getting that price? OE is around $500-$600/axle. The stop techs are $600 each
I should have clarified :Once you buy the Stoptech ( about $525 each) you only replace the rings versus OEM....so after the initial purchase it’s the same. I also got my Stoptech during a vendor sale. Finally, I found my Stoptech lasted 50% longer ( with heavy track use) so they may actually be cheaper overall. I have gone through 2 sets of factory rotors and on my second set of Stoptech.

Last edited by Twt; 01-18-2020 at 06:44 AM..
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      01-18-2020, 08:09 AM   #13
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Quote:
Originally Posted by Twt View Post
I should have clarified :Once you buy the Stoptech ( about $525 each) you only replace the rings versus OEM....so after the initial purchase it’s the same. I also got my Stoptech during a vendor sale. Finally, I found my Stoptech lasted 50% longer ( with heavy track use) so they may actually be cheaper overall. I have gone through 2 sets of factory rotors and on my second set of Stoptech.
Gotcha - thanks!
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      01-18-2020, 08:51 AM   #14
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Quote:
Originally Posted by M Fifty View Post
Have you considered a warranty claim? Cracking is not 'wear and tear'...
Rotors were covered for 2016's, not 2017 and beyond. As others have said the cracking that is happening is most certainly wear and tear.
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      07-24-2020, 01:39 PM   #15
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Bumping this thread. I see that Girodisc has the following items for the OG:

Fronts: https://www.girodisc.com/Girodisc-Fr...M4_p_6816.html

Rears: https://www.girodisc.com/Girodisc-Re...M4_p_6846.html

However, I can't find their replacement rings anywhere, despite the description saying:
"Once the Girodisc system is in place, simply replace the cast iron rotor when needed."

Does anyone know if there are F8X-specific replacement rings available?
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      08-04-2020, 02:56 PM   #16
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Quote:
Originally Posted by dcgolfdr View Post
My drilled front rotors are starting to crack and wanted to replace them with slotted rotors when they go. Does anyone make slotted rotors to work with OEM non competition calipers?
These come slotted or drilled. Zinc coating optional:


https://www.hpashop.com/Stoptech-Aer...?categoryId=-1
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      08-10-2020, 07:10 PM   #17
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Quote:
Originally Posted by gphung View Post
Bumping this thread. I see that Girodisc has the following items for the OG:

Fronts: https://www.girodisc.com/Girodisc-Fr...M4_p_6816.html

Rears: https://www.girodisc.com/Girodisc-Re...M4_p_6846.html

However, I can't find their replacement rings anywhere, despite the description saying:
"Once the Girodisc system is in place, simply replace the cast iron rotor when needed."

Does anyone know if there are F8X-specific replacement rings available?
$1200...that's absolutely mental. OG rotors are less than half that.
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      08-10-2020, 08:15 PM   #18
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Quote:
Originally Posted by BeastieBombRacing View Post
$1200...that's absolutely mental. OG rotors are less than half that.
I don’t see a listing for the M2 rings specifically, but it looks like replacement run around $600/pr, so just a few bucks more than OE rotors. So once you’re bought in, the hats are reused and new rings are bolted to them, with cost being similar.

What isn’t clear to me is whether the Girodisc or Stoptech rotors actually cool better and/or last longer than OE. Either or both could make the initial upfront cost worth it for me.

Quieter is a nice side benefit, but a bit hard to justify the added cost on noise alone.

On OE rotors, I was able to get 4 sets of RSL29s worth of use out of the front and rear rotors before the heat checking (front only) and wear were too bad for continued use.

Anyone have enough time on either of these aftermarket two piece rotors to compare on wear?
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      08-11-2020, 09:39 AM   #19
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Quote:
Originally Posted by bentom2 View Post
I don’t see a listing for the M2 rings specifically, but it looks like replacement run around $600/pr, so just a few bucks more than OE rotors. So once you’re bought in, the hats are reused and new rings are bolted to them, with cost being similar.

What isn’t clear to me is whether the Girodisc or Stoptech rotors actually cool better and/or last longer than OE. Either or both could make the initial upfront cost worth it for me.

Quieter is a nice side benefit, but a bit hard to justify the added cost on noise alone.

On OE rotors, I was able to get 4 sets of RSL29s worth of use out of the front and rear rotors before the heat checking (front only) and wear were too bad for continued use.

Anyone have enough time on either of these aftermarket two piece rotors to compare on wear?
Edit: Misread.

The only thing I can think of is that people who are spending big $ on M2 brakes are doing BBKs, and that explains the scarcity and ridiculous cost of aftermarket rotors.
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      08-11-2020, 10:35 AM   #20
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That is probably the case, the standard brakes on the M2 are very capable once pads are swapped and fluid is changed. I am definitely able to brake later and harder than many other cars when I'm out on track and I don't think experience/skill is the main difference. The 4 + 2 piston calipers and 2-piece rotors are decent, the only issue really is poor cooling.
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      08-11-2020, 10:46 AM   #21
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I'd like to have the Brembo Type 3's, but I don't think they are made for the M2, sadly.
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      08-12-2020, 06:10 PM   #22
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