F87M2C Brake retrofit on F80 M3C

[scottyb335]

Is there anyone knowledgeable on retrofitting M2C Steel brakes on M3C with steel brakes? I have installed the fronts and performed static bleeding, pressure bleeding and the DSC module bleed. When the car is off the brake pedal feels firm and solid. When the car is running and sitting stationary the pedal is solid and firm. When the vehicle starts moving the gets up to around 20mph the pedal sinks to the floor…I have coded theS2NH to the vehicle order with Protool as well. Is there any other coding required?

[Yuille36]

I have converted my M3 ZCP equipped car over to the M2 S2NH brake setup utilizing the CCB calipers on steel rotors. I have to bleed my brake system multiple times to get solid brake pedal. I didn't have to do any coding.

[N1rve]

Originally Posted by scottyb335

Is there anyone knowledgeable on retrofitting M2C Steel brakes on M3C with steel brakes? I have installed the fronts and performed static bleeding, pressure bleeding and the DSC module bleed. When the car is off the brake pedal feels firm and solid. When the car is running and sitting stationary the pedal is solid and firm. When the vehicle starts moving the gets up to around 20mph the pedal sinks to the floor…I have coded theS2NH to the vehicle order with Protool as well. Is there any other coding required?

I think you have a vacuum leak in the brake booster.

[scottyb335]

Update to the original post, when I reinstall the stock 4 pistons the brakes work as advertised. It seems to be speed related as to when I’m under 10mph the brakes feel right but anything over that, the pedal sinks to the floor and the engine brakes and revs alittle bit

[b_w.]

Can't speak to the M2 brakes specifically but all I have ever done with my alcons is pressure bleed with the motiv bleeder. What do you mean by static bleed?

[scottyb335]

Static bleed - pumping the brakes and holding while opening the bleeder port.

[M3SQRD]

I’ve done static and pressure bleeds only on my Essex/AP front and rear brake kits and I’ve had zero pedal issues. Also, I’ve had to do zero coding. It sounds like you have a vacuum leak potentially in the master cylinder because with an applied vacuum, the pedal drops to the floor. With the car off and a high applied leg force on the firm pedal, do the brakes actually stop/hold the car from moving?

[b_w.]

Originally Posted by scottyb335

Static bleed - pumping the brakes and holding while opening the bleeder port.

Gotcha. I had the exact same issue when I did that in combination with the pressure bleeder. Maybe try just sticking to the pressure bleeder and see if it improves.

[Slow M3]

I swapped from stock to 2NH and have had no issues. However I had to bleed twice, first bleed appeared to do well because there was no bubbles but the pedal was soft.

I did a second bleed by opening the nipple pumping the brake till it was hard then closing off the nipple. I went from outside nipple to inside. Did that on all 4 and it was nice and solid, hasn’t given any issues.

No coding required because the 2NH uses the same brake booster as the blue calipers.

[Yuille36]

I also had to rebleed the brakes twice to get a hard and solid pedal.

[Tommix]

Originally Posted by scottyb335

Is there anyone knowledgeable on retrofitting M2C Steel brakes on M3C with steel brakes? I have installed the fronts and performed static bleeding, pressure bleeding and the DSC module bleed. When the car is off the brake pedal feels firm and solid. When the car is running and sitting stationary the pedal is solid and firm. When the vehicle starts moving the gets up to around 20mph the pedal sinks to the floor…I have coded theS2NH to the vehicle order with Protool as well. Is there any other coding required?

How much new brake fluid did you use when bleeding? And did you bleed both sides of the brake calipers?
When I upgraded my brakes to 2NH brakes (front and rear), I used almost 4 cans of Motul RBF600 Factory Line fluid when filling/pressure bleeding.
I hope you get the problem resolved.

[scottyb335]

Update - I rearmed the front brake install again this past weekend…I removed and replaced the master cylinder and brake booster and ABS module from the M2C. Proceeded to bleed the brakes with the 2 man method, pressure bleed method and performed the DSC bleed with the Autel Ultra. I also bled the brakes with the 2 man method with the engine running and came up with the same results….

These brakes are from a 2020 F87 M2C (silver calipers with steel rotors) and my F80 M3C is a 2018. The car was coded multiple time with each SPBR, SBRE and 2NH and still produced the same result as the pedal sinking to the floor with the car rolling over 10mp…

Both the booster and master cylinder are the same P/Ns to what was in my car as well. As far as I know neither car was a prior CCB set-up.

I hope somebody has seen this issue before I throw these in the trash…

[Slow M3]

You shouldn’t have to do any coding at all, that’s the only outlier I see here.

It’s a super simple swap many people have done. It only gets complicated when you’re swapping from steel to CCB. Maybe take it to a dealer and have them diagnose then you’ll have a better idea of what direction to go.

[Yuille36]

I have recently done the 2NH caliper and rotor swap, I just had to bleed the brakes twice, and it's solid as a rock. My car now stops on a dime, and gives you back change. And I agree with Slow M3, take it to a shop and have them bleed it.