Brakes

[4play]

Originally Posted by Secret Chimp

Thanks for this. Changing from CCB's to iron via this route feels a bit like a $16k solution to a $17k problem, doesn't it? Those prices you quoted are all OEM via BMW prices, right?

Do you have any more info on how folks are adding cooling to the CCB's? I saw someone with a Porsche air deflecting paddle zip tied to a suspension part. It didn't look like it would be very effective, but looks can be deceiving.

Yes, all OEM parts via the lowest priced vendor(s) I could find in a 2 min Google search.

The car has provisions for front brake cooling in the M4 GTS upper splitter, but they are sealed off with what looks like rubber. If you open those holes up, they will connect with the Revozport kit (https://www.revozport.com/product/m3...e-cooling-kit/) to provide actual brake cooling.

Part of the problem in all of this is the GTS backing plates have no scoops for cooling air and cover basically the entire backside of the rotor, which prevent heat dissipation.

For rear brake cooling, you just need a modified backing plate and to run some tubing down under the rear lower control arm (facing forward to catch air). The rear brakes don't work nearly as hard as the fronts, so just a little bit of cooling air would help greatly.

[h_bakken]

Originally Posted by Secret Chimp

Thanks for this. Changing from CCB's to iron via this route feels a bit like a $16k solution to a $17k problem, doesn't it? Those prices you quoted are all OEM via BMW prices, right?

Do you have any more info on how folks are adding cooling to the CCB's? I saw someone with a Porsche air deflecting paddle zip tied to a suspension part. It didn't look like it would be very effective, but looks can be deceiving.

Random thought what if you remove the huge dust covers behind the discs?

Would probably allow a lot more cooling but at risk of damage to the disc?

I'd also like to know if there is a way to direct cooling air without changing to the expensive GT4 parts (assuming they would add ducting to front brakes)?

[4play]

Originally Posted by h_bakken

Random thought what is you remove the huge dust covers behind the discs? Would probably allow a lot more cooling but at risk of damage to the disc?

I'd also like to know if there is a way to direct cooling air without changing to the expensive GT4 parts (assuming they would add ducting to front brakes)?

My next project after my aftermarket splitter will be getting a front brake cooling kit together that actually works. The brake ducts from Revozport do what the GT4 parts do with regard to the backing plate. There is an intake hole in the backing plate so that air is directed towards the rotor face/center of the rotor, which cools the rotor as it flows to the outside edge and exits.

[FormulaMMM]

Originally Posted by h_bakken

Random thought what if you remove the huge dust covers behind the discs?

Would probably allow a lot more cooling but at risk of damage to the disc?

I'd also like to know if there is a way to direct cooling air without changing to the expensive GT4 parts (assuming they would add ducting to front brakes)?

If I did it all over again, would remove dust shields for cooling.

But without a doubt best move is to just swap out.

edit: Sorry, h_bakken, looking back on the thread remembered context is ccb use for novice. As before, you'll be fine. w/ or w/o cooling, dust shields, etc. The issues occur with increased pace and more brake abuse.

[h_bakken]

Originally Posted by FormulaMMM

If I did it all over again, would remove dust shields for cooling.

But without a doubt best move is to just swap out.

edit: Sorry, h_bakken, looking back on the thread remembered context is ccb use for novice. As before, you'll be fine. w/ or w/o cooling, dust shields, etc. The issues occur with increased pace and more brake abuse.

Thanks, ill be tracking very infrequently.

Actually cancelled my Dec track day due to spike in COVID cases down here, probably not a good time to be sitting in a car all day with an instructor I have never met...

[Gomeler]

I use 997 GT3 brake ducts zip-tied to the leading portion of the lower control arm for brake cooling, with 9668 calipers with no dust shields. I wasn't able to get an accurate temperature reading of my rotors and pads without the ducts, as my temperature paint maxed at 1471F/800C(which my front pad backing plates hit), but I do know with the ducts it dropped into the 1327F-1470F/720C-799C range. I boiled my fluid slightly, Motul RBF600, without the ducts after repeated ~27 minute sessions with 1/2 lap of warmup and then ~24 minutes of flat-out lapping and 1/2 lap of cooldown.

I'm sure a proper bumper ducting + backing plate to force air into the rotor would be ideal, but this isn't a racecar. I'll do racecar things on an actual racecar.

[h_bakken]

Originally Posted by Gomeler

I use 997 GT3 brake ducts zip-tied to the leading portion of the lower control arm for brake cooling, with 9668 calipers with no dust shields. I wasn't able to get an accurate temperature reading of my rotors and pads without the ducts, as my temperature paint maxed at 1471F/800C(which my front pad backing plates hit), but I do know with the ducts it dropped into the 1327F-1470F/720C-799C range. I boiled my fluid slightly, Motul RBF600, without the ducts after repeated ~27 minute sessions with 1/2 lap of warmup and then ~24 minutes of flat-out lapping and 1/2 lap of cooldown.

I'm sure a proper bumper ducting + backing plate to force air into the rotor would be ideal, but this isn't a racecar. I'll do racecar things on an actual racecar.

Good information, thanks.

It still seems strange to me that those little ducts In the front splitter are blocked off in the first place. I just went out and looked at mine. Curious.

[Secret Chimp]

Originally Posted by h_bakken

Good information, thanks.

It still seems strange to me that those little ducts In the front splitter are blocked off in the first place. I just went out and looked at mine. Curious.

I agree. They are only blocked by soft-ish rubber/plastic. I almost cut mine out before reattaching the upper splitter a few weeks ago.

[4play]

Originally Posted by Secret Chimp

I agree. They are only blocked by soft-ish rubber/plastic. I almost cut mine out before reattaching the upper splitter a few weeks ago.

Yep. Keep your eyes peeled, I'll have a thread on it in the next 1-2 weeks once I've offloaded all of my splitters.

Planning on running 1 session with ducts blocked and temperature paint and 1 session with them opened so we can at least be somewhat scientific about their efficacy.

[M3SQRD]

Originally Posted by rcompound

What part number (Carbotech) do you use for the AP application? I have the same set up and use the Ferodo DS1.11. Could also tell me the source? Thanks.

CP7790A 25 mm (need to specify the thickness). However, when I ordered a set of 1521 street pads I was told by Mike that the max thickness they actually manufacturer is 22 mm. I pushed them to make the 25 mm thick pad (and actually helped them improve their pad material shape for the 7790 backing plate) but I do not know if they actually did this. I use PFC race pads so I was fine with a 22 mm thick pad for the street.

Their pad for the rear AP 9449 caliper is CP9449 which is made by taking a 7767 pad and increasing the inner radius.

[h_bakken]

Originally Posted by 4play

Yep. Keep your eyes peeled, I'll have a thread on it in the next 1-2 weeks once I've offloaded all of my splitters.

Planning on running 1 session with ducts blocked and temperature paint and 1 session with them opened so we can at least be somewhat scientific about their efficacy.

Looking forward to hearing about this.

[rcompound]

Originally Posted by M3SQRD

CP7790A 25 mm (need to specify the thickness). However, when I ordered a set of 1521 street pads I was told by Mike that the max thickness they actually manufacturer is 22 mm. I pushed them to make the 25 mm thick pad (and actually helped them improve their pad material shape for the 7790 backing plate) but I do not know if they actually did this. I use PFC race pads so I was fine with a 22 mm thick pad for the street.

Their pad for the rear AP 9449 caliper is CP9449 which is made by taking a 7767 pad and increasing the inner radius.

Thanks for the response. It is a track only car so the 25mm is helpful to reduce time between new pads. I find I need to rotate the pads to achieve even wear.

[M3SQRD]

Originally Posted by rcompound

Thanks for the response. It is a track only car so the 25mm is helpful to reduce time between new pads. I find I need to rotate the pads to achieve even wear.

Contact them to see if they’re making the 25 mm version. If not, try G-Loc which has identical compounds to CT. The family split and some stayed with CT whereas others left and started G-Loc.

You should consider trying PFC 11 compound. I used to use CT XP compounds until I first tried PFC’s 01 compound 20 years ago. Now it’s PFC race compounds only for me.

[RSXDC5]

Throwing in a better option than M2C rotors...

Get the Girodisc 400mm/380mm ‘CCB spec’ iron race rotors & some race pads, just like the Porsche guys do. I believe it’s $1300/axle for the rotors.

[Secret Chimp]

Originally Posted by RSXDC5

Throwing in a better option than M2C rotors...

Get the Girodisc 400mm/380mm ‘CCB spec’ iron race rotors & some race pads, just like the Porsche guys do. I believe it’s $1300/axle for the rotors.

Thanks for this. I wasn't aware that anyone made a direct CCB to iron rotor replacement. I looked at Girodisc's site and they only list front rotors. Do you know if they also sell rears?

[RSXDC5]

Originally Posted by Secret Chimp

Thanks for this. I wasn't aware that anyone made a direct CCB to iron rotor replacement. I looked at Girodisc's site and they only list front rotors. Do you know if they also sell rears?

The 380mm rears have been out since mid/late October, and it looks like Girodisc hasn't updated their site yet. I believe there's a YouTube video of an m2c with them being installed if you want eyes on the product.

Since I originally spec'd my f80 with CCB, I now run the Girodisc rotors for track work. Huge huge huge difference in cooling with the Girodisc rotor vanes, A+ product overall

[JimmyS]

Santa delivered early this year .

[h_bakken]

Originally Posted by JimmyS

Santa delivered early this year .

What did you get?

[ClubsportJunkie]

Originally Posted by h_bakken

What did you get?

Looks like the AP9668/AP9449 setup!!!

Side note how was your first trip to COTA?

[BMWsports6]

Originally Posted by 786

Do you guys think it’s worth it to switch to M2C rotors/pads for a street car? My disc wear indicators look brand new and some people tell me to switch and save the CCBs while others say they’ll last forever on a street car so don’t mess with them.

If you use your car on normal streets (city, etc.) I would really not recommend switching. Your normal brakes are perfectly fine for normal use, it would just be an expensive and unused extra to switch to M2C.

[SYT_Shadow]

Is anyone interested in Girodisc iron conversion for the front brakes of a GTS?

I have a brand new set sitting in my living room