M3 Master Cylinder upgrade for E90 E92 335i

[doublespaces]

I bought one of these brake master cylinders a while ago to go along with the F30 brakes.



Before I dive into this, any input on how to best go about it? It doesn't seem to difficult but I'd like to avoid any ABS headaches.


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Okay, so I got this installed, here are some photos and info bits.

Prep: Drain the fluid out of the reservoir. This is probably obvious but if you're an idiot like me and think you can be slick, you'll end up spilling brake fluid everywhere and end up spending 3x the time trying to clean it up so you paint doesn't get corroded. Bleed the brakes or do whatever you need to ensure there is no fluid in the reservoir, then pull the tank off as it opens up the necessary working room. You can pull it off as a unit but you end up spilling fluid down the body and it comes out down behind the fender liner, some areas are not reachable with a cloth.

The stock master cylinder/reservoir


Remove the pin holding the tank to the master cylinder(easier to see when removed):


User a screw driver to rock the tank out of the rubber seals(Make sure you've got something to soak up any extra fluid, chances are there will be some.



Remove the two nuts holding the master cylinder:


Grab one of the plugs from the new master cylinder if you have them, unscrew one of the lines from the side and plug the master cylinder hole so fluid doesn't pour out:


Repeat with the other line and the master cylinder should come out. Its a tight fit but it will come out, you may need to make some room with the metal lines in that area. I also used the plugs from my calipers to cap the lines so nothing else would drip out:


Make sure you've cleaned up any fluid that may have dripped down as this is your last chance to fit your hand down in there and put the new master cylinder on:


Put the lines back into the new master cylinder and tighten the two nuts back on:


Push the reservoir back onto the seals and replace the pin:


Fill the reservoir back up and use a power bleeder to push all the air out and then use INPA to evacuate any remaining air from the system using this guide:

INPA DSC Brake Bleed

This is a supplemental process to bleeding your brakes the normal way with a pressure or vacuum bleeder. You'll need to make sure you have plenty of brake fluid, because each procedure tends to drain the fluid reservoir almost completely. Make sure you have an OBD cable connected to the car and...

bmw.spoolstreet.com

 

[E92 420]

You should be fine as long as you have INPA or a foxwell scanner so you can activate the abs module and cycle it to bleed the air out of it. INPA is better, it does a much more thorough job. air can be a real pain to get out of the module without the above.

 

[fmorelli]

So I was looking at doing this with my Z4, but of course ... built by interns ... the Z4 MC is not the same as the other e8x/e9x cars. At a minimum the lines come out the other side; and not that I can't bend new lines but ...

A friend of mine is running 380mm all around with a stock MC and says it works great, great pedal feel, etc.

I understand that, in doing the brake upgrade, one wants to do some coding around the DSC (regardless of MC change or not).

All that said, I'm in on this thread to see what goes on ...

Filippo

 

[Illsic_Design]

So I was looking at doing this with my Z4, but of course ... built by interns ... the Z4 MC is not the same as the other e8x/e9x cars. At a minimum the lines come out the other side; and not that I can't bend new lines but ...

A friend of mine is running 380mm all around with a stock MC and says it works great, great pedal feel, etc.

I understand that, in doing the brake upgrade, one wants to do some coding around the DSC (regardless of MC change or not).

All that said, I'm in on this thread to see what goes on ...

Filippo

Most(E9x guys) say that after the 370 calipers front/ 345 calipers rear that the pedal is a little soft. Putting in the M3 master cylinder with the bigger bore fixes the issue. There is no coding necessary after installing the M3 master cylinder from anything I've read on the swap.

I've heard the master can be a pain to get out, especially on coupes, as there is a bunch of stuff all around it. Everyone says to make sure to use INPA or similar to bleed the ABS module and shouldn't have any issues.

I'm still waiting to do the swap, need to buy some rear rotors and then I'll be ready.

 

[doublespaces]

Most(E9x guys) say that after the 370 calipers front/ 345 calipers rear that the pedal is a little soft. Putting in the M3 master cylinder with the bigger bore fixes the issue. There is no coding necessary after installing the M3 master cylinder from anything I've read on the swap.

I've heard the master can be a pain to get out, especially on coupes, as there is a bunch of stuff all around it. Everyone says to make sure to use INPA or similar to bleed the ABS module and shouldn't have any issues.

I'm still waiting to do the swap, need to buy some rear rotors and then I'll be ready.

Did you get the offset bushings or going another route?

I intend to update the first post with photos as a mini guide.

 

[Illsic_Design]

I will be using offset bushings and 535i E60 rotors

 

[fmorelli]

@Seb335i - if you have a moment, can you please share the information on what should be coded when the 370/345 brakes are installed on the E90?

Filippo

 

[Illsic_Design]

@Seb335i - if you have a moment, can you please share the information on what should be coded when the 370/345 brakes are installed on the E90?

Filippo

you only need to code if you have a 330/328/325 and you code in the performance brake VO. If you have a 335 this is not necessary.

 

[Torgus]

So I was looking at doing this with my Z4, but of course ... built by interns ... the Z4 MC is not the same as the other e8x/e9x cars. At a minimum the lines come out the other side; and not that I can't bend new lines but

Hah of course it is not. Amazing the cost BMW spent to make everything different for a low volume production car. I feel for you man. The z4 is bad ass but man they man an enthusiast pay for it.

Most(E9x guys) say that after the 370 calipers front/ 345 calipers rear that the pedal is a little soft. Putting in the M3 master cylinder with the bigger bore fixes the issue. There is no coding necessary after installing the M3 master cylinder from anything I've read on the swap.

I've heard the master can be a pain to get out, especially on coupes, as there is a bunch of stuff all around it. Everyone says to make sure to use INPA or similar to bleed the ABS module and shouldn't have any issues.

I'm still waiting to do the swap, need to buy some rear rotors and then I'll be ready.

FWIW my stoptech BBK feels just fine with the stock MC. That being said it is designed for the chassis/car. People putting a mish mash of calipers front and rear from other cars/bmw that are not designed for the car I can see the M3 MC potentially helping. When you add a bunch of extra pistons of larger/various sizes I don't think the stock MC & ABS system likes it much, this is just conjecture mind you, no experience on this specific platform.

To go on, if you NEED a BBK. I would buy one designed for the car, they are half priced used usually for $3500 give or take. If you just want larger calipers for looks go for it. But the chance of throwing on rando calipers front and rear and expecting the brake bias and ABS to function correctly is NOT going to happen(unless you are very lucky or actually do the math).

 

[Seb335i]

you only need to code if you have a 330/328/325 and you code in the performance brake VO. If you have a 335 this is not necessary.

I don’t agree with you on my former 335d e90 I retrofited the 135i Brembo 6 pods callipers and there is a huge difference in pedal feel with and without coding.

You have to add +SPBR to your FA then code code your DSC

 

[Asbjorn]

So I was looking at doing this with my Z4, but of course ... built by interns ... the Z4 MC is not the same as the other e8x/e9x cars. At a minimum the lines come out the other side; and not that I can't bend new lines but ...

A friend of mine is running 380mm all around with a stock MC and says it works great, great pedal feel, etc.

I understand that, in doing the brake upgrade, one wants to do some coding around the DSC (regardless of MC change or not).

All that said, I'm in on this thread to see what goes on ...

Filippo

And I can testify that the E9x M master cylinder doesn't fit the Z4 either. Buy an M4 and this problem is solved... that car comes with two different brake master cylinders from factory (the ceramic versions is bigger). Much happier modding life right there.

Good news though... If you keep the caliper piston area the same or smaller than oem, the brake pedal travel won't increase at all. Lots of people make the mistake of not checking this before upgrading. You can get 6 piston calipers that are smaller than OEM and four piston calipers that are actually bigger. It depends on the caliper design, and you "just" have to pick the right size for your car. As an example, my rear 6 pot caliper is actually slighlty smaller than the oem rear caliper in terms of total piston size.

For 35is/EU 35i the front area is 2x2552mm2 and rear is 2x1386 per side. And while disc diameter impacts brake torque and heat capacity, it won't significantly change how long you need to press the brake pedal to move the pistons. Of much greater importance here is the friction coefficient of the brake pads. And running square 380mm rotors won't necessary be right for brake bias either.

An easy way to get brakes that bite harder is to simply install pads with higher friction coefficient. OEM is on the low side. EBC yellows are somewhere in the middle in terms of bite. OK but nothing special. Semi-metallic brake pads with high friction coefficient and aggressive bite can be quite addicting and fun to drive, but also come with lots of dust, wear etc.

I think most people underrate the importance of brake pads, while overrating the importance of calipers and stuff like brake lines.

 

[Torgus]

And I can testify that the E9x M master cylinder doesn't fit the Z4 either. Buy an M4 and this problem is solved... that car comes with two different brake master cylinders from factory (the ceramic versions is bigger). Much happier modding life right there.

Good news though... If you keep the caliper piston area the same or smaller than oem, the brake pedal travel won't increase at all. Lots of people make the mistake of not checking this before upgrading. You can get 6 piston calipers that are smaller than OEM and four piston calipers that are actually bigger. It depends on the caliper design, and you "just" have to pick the right size for your car. As an example, my rear 6 pot caliper is actually slighlty smaller than the oem rear caliper in terms of total piston size.

For 35is/EU 35i the front area is 2x2552mm2 and rear is 2x1386 per side. And while disc diameter impacts brake torque and heat capacity, it won't significantly change how long you need to press the brake pedal to move the pistons. Of much greater importance here is the friction coefficient of the brake pads. And running square 380mm rotors won't necessary be right for brake bias either.

An easy way to get brakes that bite harder is to simply install pads with higher friction coefficient. OEM is on the low side. EBC yellows are somewhere in the middle in terms of bite. OK but nothing special. Semi-metallic brake pads with high friction coefficient and aggressive bite can be quite addicting and fun to drive, but also come with lots of dust, wear etc.

I think most people underrate the importance of brake pads, while overrating the importance of calipers and stuff like brake lines.

This guy gets it.

I think most people underrate the importance of brake pads, while overrating the importance of calipers and stuff like brake lines.

This. A 1000 times this.


OEM calipers work just fine. Good fluid, the right pads for your application, and a decent friction surface will suffice for 99% of people.

 

[Bnks334]

I don’t agree with on my former 335d e90 I retrofited the 135i Brembo 6 pods callipers and there a huge difference in pedal feel with and without coding.

You have to add +SPBR to your FA then code code your DSC

Can you upload the trace file here after doing this? I'd like to compare line by line to a stock DSC trace file.

Also gotta agree that pad material will make massively more difference than a BBK with the generic pads they usually come with. Get a good pad like a hawk DTC-70 or carbotech XP12 or something. Run brake ducts to keep them cool. Stock calipers and rotors and plenty enough. BBK is nice bling but damn think of all the other things these cars need and $3,500 goes a long way. Brakes aren't holding these cars back any... at least not with some basic brake mods like mentioned above.

 

[KClemente]

@doublespaces How does your brake pedal feel with your F30 Brembos and the M3 master? I've been putting off installing an M3 master on my car for years now and would like to know if it'll get rid of the spongy feel

 

[fmorelli]

@doublespaces How does your brake pedal feel with your F30 Brembos and the M3 master? I've been putting off installing an M3 master on my car for years now and would like to know if it'll get rid of the spongy feel

I have some of the same, and that's with going through the BMW ISTA brake bleed, and doing manual bleeds. Unfortunately the E89 brake booster/MC is .... yep ... not like the E9x ... so a booster swap is non trivial. I've not seen anyone else work out a swap and I don't have the cycles to sort it out.

 

[doublespaces]

To be honest with you, my F30 brakes have felt hard. Putting in the m3 master cylinder did nothing to change that as far as I can tell. I wouldn't have described my brakes as spongey even before the m3 cylinder either. They feel hard and borderline unresponsive, like I have to mash on them for the car to stop. Not sure if that's normal or a problem with my installation, aftermarket rear rotors or something else. But when I do press on them hard the car comes to a halt quickly. There is no comparing the initial bite to factory brakes though, I think I have ceramics on there now which adds to this feeling. Iirc, they are hawks pads, but they felt this way when I had the oem pads as well, not sure what those were made of.

Also, I did the stainless steel brake line kit simultaneously with the brakes so I'm not sure what's contributing to the feel more, the brakes, pad type or lines.

But it's worth pointing out that I didn't follow the typical upgrade path for the rear brakes. My calipers are machined for the f30 rotors but I used the E60 rotor with the eccentric bushing (and spacers to recompensate for missing caliper material)

 

[KClemente]

To be honest with you, my F30 brakes have felt hard. Putting in the m3 master cylinder did nothing to change that as far as I can tell. I wouldn't have described my brakes as spongey even before the m3 cylinder either. They feel hard and borderline unresponsive, like I have to mash on them for the car to stop. Not sure if that's normal or a problem with my installation, aftermarket rear rotors or something else. But when I do press on them hard the car comes to a halt quickly. There is no comparing the initial bite to factory brakes though, I think I have ceramics on there now which adds to this feeling. Iirc, they are hawks pads, but they felt this way when I had the oem pads as well, not sure what those were made of.

Also, I did the stainless steel brake line kit simultaneously with the brakes so I'm not sure what's contributing to the feel more, the brakes, pad type or lines.

But it's worth pointing out that I didn't follow the typical upgrade path for the rear brakes. My calipers are machined for the f30 rotors but I used the E60 rotor with the eccentric bushing (and spacers to recompensate for missing caliper material)

Interesting take on the hard brake pedal. We're completely opposite on that but if I do mash on my brake pedal, it still has enough bite to easily hit ABS going highway speeds.

Now I'm not trying to start an argument here but I do believe that the SS brake lines = firm pedal is a myth. Maybe. At least on a modern car like ours where DOT testing is actually pretty intensive for brake lines.

Do you by any chance have a booster leak? That may contribute to a hard brake pedal as you have less assist than normal

Now I finally secured a set of master and booster from an M3 and noticed that the booster is in fact "different" than non-M boosters. M3 Brake Booster 1M's and E9x M3's all share this specific booster and there's got to be a reason for that.

 

[doublespaces]

Interesting take on the hard brake pedal. We're completely opposite on that but if I do mash on my brake pedal, it still has enough bite to easily hit ABS going highway speeds.

Now I'm not trying to start an argument here but I do believe that the SS brake lines = firm pedal is a myth. Maybe. At least on a modern car like ours where DOT testing is actually pretty intensive for brake lines.

Do you by any chance have a booster leak? That may contribute to a hard brake pedal as you have less assist than normal

Now I finally secured a set of master and booster from an M3 and noticed that the booster is in fact "different" than non-M boosters. M3 Brake Booster 1M's and E9x M3's all share this specific booster and there's got to be a reason for that.

I don't believe I have a vaccum leak, I just run a single hose from the pump directly over to the booster, removed the boost solenoid barbs fitting because I am single turbo. A lack of assist is kinda what it reminds me of, so maybe I'll double check the line.

The brakes have stopping power, but you have to lean into them a little more than it seems I'd need to at first. Once I am pressing them, while hard (I know I said unresponsive) I could describe the pedal as fairly linear.