2 piece aftermarket rotors - better cooling

[m4forum]

I am fighting brake overheating on M4 at Watkins Glen and Grattan. After 15min start to lose confidence on brakes. My rotor temps are 1400F. Crazy !!!!
Cooling ducts on front and rear but it doesn't resolve the issue.
I know some people go with BBK but I am not planning to send 10k. It doesn't make sense if should have a more affordable solution.
I am looking into Girodisc and they seem to have good design, 2 piece, much more vents (could not count). Just wonder if somebody has some experience with girodisc or even StopTech rotors and their thermal performance in comparison with OE rotors.

[biofluke]

Try titanium brake shims, they will help reduce heat transfer from the Rotor to the caliper. They go on the back of the brake pads. There are some other threads about it, I've seen them for sale on eBay for the F8X platform, but there may be other better sources.

[m4forum]

tks for the reply. The brake thermal efficiency needs to be view from the sourcing and dissipation. The source is consequence of vehicle mass, speed and tire grip. There isn't to do there as cannot reduce weight substantially or speed or grip. The focus must be on dissipation : the heat generated on fiction between pad and rotor goes to rotors, pads and brake fluid. On brake fluid the titanium shims help mitigation heat propagation from pad. On rotor heat the cooling helps dissipating some of the heat through the air. Adding cooling ducts helps here for sure.
On my case I have already tried shims and brake cooling ... they help but I need more as my rotors are still getting 1400F ....crazy hot.
There isn't much I can do w/o focus on rotor-pad heat there is where some my question on better brake disc with better cooling performance which could improve the overall thermal efficiency of the system by dissipating more heat through the air and lower overall stress on brakes.
In general BBK can withstand higher heat stress but not necessarily lower overall temperature.

[F80Speed77]

Any two piece rotor design with an aluminum hat is going to make a world of difference on rotor temperature. I made the switch to Girodisc on a previous platform and it was night/day.

[swagon]

Originally Posted by F80Speed77

Any two piece rotor design with an aluminum hat is going to make a world of difference on rotor temperature. I made the switch to Girodisc on a previous platform and it was night/day.

Aren't the stock rotor hats aluminium too?

[m4forum]

I believe they are. Does anybody has experience with Girodisc 2 piece rotor regarding temperature? Soon I will need to replace my rotors and wonder if worth the additional costs.

[F80Speed77]

Interesting had to go read up on it but yeah it sounds like they are so maybe there won't be as big of a change as on my previous car (2016 STI).

Racing Brake also makes a two-piece rotor that is 2mm wider than stock. I was going to give them a go hopefully before my event at Road America (Sept) but if not then definitely for next year.

[hC1001]

How are you ducting air? You have hoses going to backing plates? Where did you mount the inlets?

[M3SQRD]

Originally Posted by F80Speed77

Interesting had to go read up on it but yeah it sounds like they are so maybe there won't be as big of a change as on my previous car (2016 STI).

Racing Brake also makes a two-piece rotor that is 2mm wider than stock. I was going to give them a go hopefully before my event at Road America (Sept) but if not then definitely for next year.

The OEM cast Al hat with steel pins creates a flow restriction to the iron brake rotor vanes. The F8x design is an improvement over the e9x design but still more restrictive than a free-floating face-mount Al hat (AP, PFC, Alcon, etc).

[m4forum]

I have front and rear cooling but still not enough.





I talked to Racing Brakes to better understand their solution but unfortunately their support was really weak ... could not get any information about the potential gains ... I believe there is some but not sure how much. it is just amazing how those products are released w/o much data to share ... or the data is not that good to convince customers. Looks like it comes back to us to prove it out.

[RSXDC5]

Girodisc 2-piece rotors, remove your rotor shields on the inside, brake ducting if u can manage, Raybestos ST43 pads or better, Castrol SRF brake fluid or similar.

Always do a cool down lap after your session.

I recently chatted with Girodisc at length, their rotors have a huge number of vanes to facilitate cooling, and their rotor material blend/mix makes for a very durable rotor. Give them a call! You won’t regret it!

[m4forum]

Originally Posted by RSXDC5

Girodisc 2-piece rotors, remove your rotor shields on the inside, brake ducting if u can manage, Raybestos ST43 pads or better, Castrol SRF brake fluid or similar.

Always do a cool down lap after your session.

I recently chatted with Girodisc at length, their rotors have a huge number of vanes to facilitate cooling, and their rotor material blend/mix makes for a very durable rotor. Give them a call! You won’t regret it!

I talked to Girodisc but them dont have any data to show how much better it will get. Their rotor has more vanes what should improve cooling but how much? I am switching to a different pad but in theory it wont change as speed and weight are the same.

[RSXDC5]

Sometimes you don’t need data up front when it’s an established product design that works on many other cars/track cars, and used with great results!

We only have a couple options for 2-piece aftermarket rotors for OEM calipers, and Girodisc seems to be the best option. The only other ways you have to manage heat are with a caliper change or to improve your ducting or Ti shims...but u specified no BBK, right?

If u want a BBK, AP/Essex is where it’s at

[m4forum]

Appreciate the feedback. I believe an aftermarket 2 piece rotor will help (Girodisc) but is that enough? I want to believe an aftermarket caliper is not required to drive this car to the limit.

[Geez3]

If you look at the stock Iron rotors you can see there is not much attaching the hat to the actually rotor. There are "Pins" as the connection point, so I would guess that not much heat is transferred between the hat and rotor.

Weight wise, here are my findings:
Alcon front = 25.6lb / +1.2lbs
Stoptech Aerorotor = 23.8lb / (-0.6)lb
Girodisc = 22.65lb / (-1.75)lb
Platz1 = ?

With as much weight on the front of the F80 I think the the most economical solution is removing the dust shield entirely and fabricate brake ducting from the nose of the car. The GT4 pulls from the splitter and bumper.

I have been thinking of 3D printing or finding some ducting that will fit on my MPP front splitter at the same area of the GT4 duct.

[BuLoOoSki]

EBC have also recently released 2-piece rotors for the stock calipers. However, just fronts, rears are expected to be released in Q4.

https://ebcbrakes.com/ebc-news/ebc-b...-m2-m3-m4-f8x/

[m4forum]

Originally Posted by Geez3

If you look at the stock Iron rotors you can see there is not much attaching the hat to the actually rotor. There are "Pins" as the connection point, so I would guess that not much heat is transferred between the hat and rotor.

Weight wise, here are my findings:
Alcon front = 25.6lb / +1.2lbs
Stoptech Aerorotor = 23.8lb / (-0.6)lb
Girodisc = 22.65lb / (-1.75)lb
Platz1 = ?

With as much weight on the front of the F80 I think the the most economical solution is removing the dust shield entirely and fabricate brake ducting from the nose of the car. The GT4 pulls from the splitter and bumper.

I have been thinking of 3D printing or finding some ducting that will fit on my MPP front splitter at the same area of the GT4 duct.

The concern I have regarding removal of heat shield is the proximity with the ball joints with rotor temps higher than 1000F it could damage the rubber. There is a test I found online about somebody that removed it ... the gains are not that huge. regarding the ducts see what I got .... very happy with it 3D printing.

[wigaster]

What fluid, pads, and tires/size are you running where you are encountering these overheating issues? Also just to confirm are you using any electronic aids (MDM etc)? I have the girodisc rotors on my f80 FYI

[m4forum]

Originally Posted by wigaster

What fluid, pads, and tires/size are you running where you are encountering these overheating issues? Also just to confirm are you using any electronic aids (MDM etc)? I have the girodisc rotors on my f80 FYI

I am using Motul 600, PFC 08 pads, NT01 tires 275/305. MDM off and cooling brakes ducts as can find on picture. My next event is one week from now at Mid Ohio. I plan to run Ferodo 3.12 as test point but in theory pad material should not impact the amount of heat is generated as heat = speed^2 vs mass. Mid Ohio offers low mechanical grip so potentially it can help ... hopefully in Sep I can come back to Grattan for a comparison.

Anyway my last chance is to replace the rotors reason I am asking the question.
Did you notice any difference with Girodisc?

[wigaster]

Originally Posted by m4forum

I am using Motul 600, PFC 08 pads, NT01 tires 275/305. MDM off and cooling brakes ducts as can find on picture. My next event is one week from now at Mid Ohio. I plan to run Ferodo 3.12 as test point but in theory pad material should not impact the amount of heat is generated as heat = speed^2 vs mass. Mid Ohio offers low mechanical grip so potentially it can help ... hopefully in Sep I can come back to Grattan for a comparison.

Anyway my last chance is to replace the rotors reason I am asking the question.
Did you notice any difference with Girodisc?

I honestly haven't noticed a huge difference but haven't had a ton of track time on them this year. Only times I've had brake issues were when I didn't have fresh fluid. I'm running 2:08 flat at VIR so the brakes are getting a workout. The lads can make a difference with heat generated as your quoted equation doesn't take into account friction. Grippier pads are going to generate more heat. I've not had this issue with the pagid rs29

[m4forum]

I was able to track the can at Mid Ohio. Good news is that no brake issues but also the track is different and less demanding than Watkins Glen. I noticed the Ferodo 3.12 wears much faster than PFC08 which could be reason my breaks were working extremely hard to stop the car (longer braking time). Need more testing. See EBC rotors are the most affordable solution $1050 pair. Somebody with experience on them.
One more piece of data : my calipers turned green as known on this community but just the outside portion of the caliper the inside is still blue -> great indication the EO 2 piece is not floating want can cause cracks a lot of people shared on this forum.

[fanatic1]

Originally Posted by m4forum

I was able to track the can at Mid Ohio. Good news is that no brake issues but also the track is different and less demanding than Watkins Glen. I noticed the Ferodo 3.12 wears much faster than PFC08 which could be reason my breaks were working extremely hard to stop the car (longer braking time). Need more testing. See EBC rotors are the most affordable solution $1050 pair. Somebody with experience on them.
One more piece of data : my calipers turned green as known on this community but just the outside portion of the caliper the inside is still blue -> great indication the EO 2 piece is not floating want can cause cracks a lot of people shared on this forum.

Grattan, used to be home track - love that track.

Girodisc, no personal experience, but fellow track rat swears by them. I am running BBK but have had similar experience with DS3.12, great heat tolerance and bite, but they do wear rather quickly under heavy use (what pad doesn’t). Pads are indeed a trade off, pad life vs disc life.


“I always tell people that brake pads are like ice cream, there are a million flavors and everyone likes something different. They can each have a very unique feel and performance. Some people like the feel of one, but not the other.“
Jim Ritter