128i with 135i front brakes

racer_951 · 11-26-2022, 12:11 AM

I just noticed the brake is more effective but the pedal seems to go down further before the brakes start to bite. I’m running stock 128i master cylinder. I read from this forum that when switching to larger brakes (6 piston caliper in this case), I should also upgrade the master cylinder to a 135i MC. I think it makes sense but I just want to confirm that. I also read on the forum some of you use M3 master cylinder. I couldn’t find the post. Overall the brake works very well in the last 3 track days. No trouble with heel toe. But I prefer firmer brake pedal feel.

racer_951 · 11-26-2022, 12:17 AM

I also want to add: I used Motive Brake bleeder to bleed the brake. I also plan to try the 2 person method when I replace the front rotors (they got warped from the last track day)

Olgeezer1 · 01-22-2023, 04:37 PM

There should be no need to replace your master cylinder. I have the factory upgrade brakes which use the Brembo 6 piston fronts , exactly the same as 135 brakes and there was no need to upgrade the master cylinder. Pedal is firm , no issues. Sounds more like air in the system or spongy brakes hoses.

tsk94 · 01-23-2023, 10:56 AM

Did you do the BMW Performance brake coding? I believe that would make a difference.
I think you need to take it to a dealer, and it's no cheap, but I'd suggest doing that before going down the route of MC swap.

Olgeezer1 · 01-29-2023, 07:16 PM

There is coding for the Performance brakes but don't know if you'd feel any difference. I didn't. I believe that particular coding affects the interaction with the Traction control system. There are however several items in the DTC system that interfere with performance braking, cut engine power, and interfere with brake feel. Multiple hard brake applications (track) trigger this interference . This stuff can be easily coded out with the tool of your choice. I used Bimmergeeks Protool to remove all those interferences as well as turn off the E-diff. ( due to LSD install ). Don't know if this helps but it can't hurt.

alindquist · 02-01-2023, 07:27 AM

To be honest, the 6-pot calipers from 135i are crap for tracking. They're just "good looking" calipers with bad performance. You won't get that firm pedal feel with them, swap them for something better. I've been it the same position as you. Changing for stainless pistons will help, but it won't solve the problem completely..

I went for Stoptech calipers and a M3 master cylinder, and now it works.

amg6975 · 02-01-2023, 09:26 AM

What he said ^ 135 brakes are not actually good brakes. The E9x 335i brakes are far superior in every way except looks.

Also, coding will not change brake feel, that is just for DSC/ABS intervention algorithms. If you're not in ABS or DSC (or BFD, ELSD, etc) the connection from the pedal to the caliper is purely mechanical.

11-26-2022, 12:11 AM	#1
racer_951 Private First Class 55 Rep 162 Posts Drives: e92 M3, Cayman S, 128i MS, SPB Join Date: Sep 2012 Location: San Jose iTrader: (0)	128i with 135i front brakes - master cylinder suggestions I just noticed the brake is more effective but the pedal seems to go down further before the brakes start to bite. I’m running stock 128i master cylinder. I read from this forum that when switching to larger brakes (6 piston caliper in this case), I should also upgrade the master cylinder to a 135i MC. I think it makes sense but I just want to confirm that. I also read on the forum some of you use M3 master cylinder. I couldn’t find the post. Overall the brake works very well in the last 3 track days. No trouble with heel toe. But I prefer firmer brake pedal feel.
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11-26-2022, 12:17 AM	#2
racer_951 Private First Class 55 Rep 162 Posts Drives: e92 M3, Cayman S, 128i MS, SPB Join Date: Sep 2012 Location: San Jose iTrader: (0)	I also want to add: I used Motive Brake bleeder to bleed the brake. I also plan to try the 2 person method when I replace the front rotors (they got warped from the last track day)
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01-22-2023, 04:37 PM	#3
Olgeezer1 Lieutenant 183 Rep 505 Posts Drives: 2010 128i 6MT Sport Pkg. 18" Join Date: Jul 2013 Location: Ottawa, Canada iTrader: (0) Garage List 2010 E82 128i N52 [0.00]	There should be no need to replace your master cylinder. I have the factory upgrade brakes which use the Brembo 6 piston fronts , exactly the same as 135 brakes and there was no need to upgrade the master cylinder. Pedal is firm , no issues. Sounds more like air in the system or spongy brakes hoses.
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01-23-2023, 10:56 AM	#4
tsk94 Lieutenant Colonel 1522 Rep 1,591 Posts Drives: E92 M3, E82 128i, F82 M4, E36 Join Date: May 2017 Location: Calgary iTrader: (2)	Did you do the BMW Performance brake coding? I believe that would make a difference. I think you need to take it to a dealer, and it's no cheap, but I'd suggest doing that before going down the route of MC swap.
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01-29-2023, 07:16 PM	#5
Olgeezer1 Lieutenant 183 Rep 505 Posts Drives: 2010 128i 6MT Sport Pkg. 18" Join Date: Jul 2013 Location: Ottawa, Canada iTrader: (0) Garage List 2010 E82 128i N52 [0.00]	There is coding for the Performance brakes but don't know if you'd feel any difference. I didn't. I believe that particular coding affects the interaction with the Traction control system. There are however several items in the DTC system that interfere with performance braking, cut engine power, and interfere with brake feel. Multiple hard brake applications (track) trigger this interference . This stuff can be easily coded out with the tool of your choice. I used Bimmergeeks Protool to remove all those interferences as well as turn off the E-diff. ( due to LSD install ). Don't know if this helps but it can't hurt.
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02-01-2023, 07:27 AM	#6
alindquist Enlisted Member 148 Rep 47 Posts Drives: BMW 135I Join Date: Jan 2020 Location: Sweden iTrader: (0)	To be honest, the 6-pot calipers from 135i are crap for tracking. They're just "good looking" calipers with bad performance. You won't get that firm pedal feel with them, swap them for something better. I've been it the same position as you. Changing for stainless pistons will help, but it won't solve the problem completely.. I went for Stoptech calipers and a M3 master cylinder, and now it works.
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02-01-2023, 09:26 AM	#7
amg6975 Captain 496 Rep 643 Posts Drives: '12 M1.5, '05 ZHP, '98 M3/4/5 Join Date: May 2017 Location: Rochester NY iTrader: (0)	What he said ^ 135 brakes are not actually good brakes. The E9x 335i brakes are far superior in every way except looks. Also, coding will not change brake feel, that is just for DSC/ABS intervention algorithms. If you're not in ABS or DSC (or BFD, ELSD, etc) the connection from the pedal to the caliper is purely mechanical.
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