M2C 2NH rear only on F82

[m4forum]

I know that 2NH is a direct plug-n-play on F82 and there is a lot of information already on this site. Conding isn't required.

Just wonder if can replace only the rear as I have AP Racing on the front. The major advantage I see is that stock F82 M4 has on rear 370x24 but the M2C is 380x28 which adds substantial more thermal capacity what is a must for this car as you all know the rear brakes really work hard on M4.

Trying any alternative to avoid BBK on rear.

[Encanto]

Originally Posted by m4forum

I know that 2NH is a direct plug-n-play on F82 and there is a lot of information already on this site. Conding isn't required.

Just wonder if can replace only the rear as I have AP Racing on the front. The major advantage I see is that stock F82 M4 has on rear 370x24 but the M2C is 380x28 which adds substantial more thermal capacity what is a must for this car as you all know the rear brakes really work hard on M4.

Trying any alternative to avoid BBK on rear.

Yes, you can.

[m4forum]

tks for the feedback. I did some calculation considering piston area, disc size and effective disc diameter. I found out on M2C there is 4-5% bias shift to the front what I dont believe is negligible but in reality not sure how much it will impact overall brake performance. One alternative is to use a more aggressive pad on the rear to offset that. I estimated 10-15% higher Mu can make the trick.
Interested if somebody took this path and your experience with brake performance and rear caliper temperatures.
If you look on AP Racing site the rear BBK for M4 and M2C are different to offset the difference in piston area between them.

[Encanto]

Originally Posted by m4forum

tks for the feedback. I did some calculation considering piston area, disc size and effective disc diameter. I found out on M2C there is 4-5% bias shift to the front what I dont believe is negligible but in reality not sure how much it will impact overall brake performance. One alternative is to use a more aggressive pad on the rear to offset that. I estimated 10-15% higher Mu can make the trick.
Interested if somebody took this path and your experience with brake performance and rear caliper temperatures.
If you look on AP Racing site the rear BBK for M4 and M2C are different to offset the difference in piston area between them.

The difference in piston area between the M4 and the M2C is because of the larger rotor and 4 piston caliper on the M2C.

When you look at the front and rear piston area bias of the 6-piston/400mm rotors/front and 4-piston/380mm rotors/rear of the M2C then that piston area bias proportion is similar to the 4-piston/380mm rotor/front and 2-piston/370mm rotor/rear of the M4 (no CCB). This calculation was made in the thread of replacing the M3/M4 4/2-piston brakes with the M2C 6/4-piston combo.

If your AP racing front BBK approximates the bias of the M2C front bias then the M2C rear bias will match.

[m4forum]

I believe you are referring to the calculation below. On my calculation the rear piston diameter is 44mm instead of 40mm used below. Based on my research online 44m is the right number but I will get my car back from shop this weekend and will measure to confirm.

If 44mm is confirmed there is a bias difference as I pointed out if 40mm is confirmed is a plug-n-play.


CCB (gold) brake calipers:
Front 6 pistons: 30/34/36mm = 52.7 cm^2 (68%)
Rear 4 pistons: 28/28mm = 24.6 cm^2 (32%)
Total: 77.4 cm^2
Iron (blue) brake calipers:
Front 4 pistons: 40/40mm = 50.3 cm^2 (67%)
Rear 2 pisotns: 40mm cm = 25.1 cm^2 (33%)
Total: 75.4 cm^2

[m4forum]

I had the chance to measure rear caliper piston diameter and confirm it has 44mm. So it means there is a bias shift to front around 4-5%.

M4 iron
Front 4 pistons : 40/40mm = 50.26 cm^2 (62%)
Rear 2 pistons : 44mm = 30.40 cm^2 (38%)
Total : 80.67 cm^2

M2C
Front 6 pistons : 30/34/36mm = 52.65 cm^2 (68%)
Rear 4 pistons : 28/28mm = 24.63 cm^2 (32%)
Total : 77.28 cm^2

As you can see the shift in piston area is around 6% but as this is slightly offset due difference in rotor diameter but still not enough to match M4 bias.

To summarize : if you shift to M2C your brake bias will change 4-5% to the front.