No announcement yet.

do i need bigger master with bbk?

  • Filter
  • Time
  • Show
Clear All
new posts

    do i need bigger master with bbk?

    hey i have 5lug sleeves that use e46 m3 fronts and e39 rears.
    So that's 60mm front and i think either 40/42mm rears.

    my brakes kinda have an initial long soft travel until the brakes
    actually bite and when they bite they bite pretty hard so it's kinda easy to lock up if not careful.

    i would have to pump the pedal and then the brakes would feel normal.
    firm and predictable.

    the m3 uses the bigger 25mm master so i'm assuming that's the problem but idk. or does this sound like something else. i don't see other people posting about needing the bigger master with the swap so that's why i'm like

    Bigbois by jet jones, on Flickr

    I have the same on my other car. Started out with driving it on stock master, everything worked good. But after the upgrade to e32 one, I don't want to go back to the stock e30.
    You might as well do it now to avoid having to bleed the brakes again.


      Yes. I suggest a bigger 25,4mm MC (1"). Most likely commonly found on the e32 750iL. You may want to remove the OEM fixed bias valve too in order to maximize rear braking.
      Brake harder. Go faster. No shit.



        ITEM 5 ? got a p/n for something to replace it with?
        89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

        new build thread


          i didn't even know that was there.

          ya the front would feel like it did 99% of the braking. Fronts where covered in dust in a day the rears where clean.
          redoing my exhaust today then i'll test the brakes with the e32 mc.

          crazy nobody has complained about it. fkn terrible.
          i would of rather stayed stock with some race pads.


            Roughly, front brakes do 2/3 of the braking and rear brakes do 1/3. Perhaps even a bit more front biased than that for street cars with a softish suspension (more weight transfer on the front wheels under hard braking and rear wheels unloading).

            Stock e30 masters are 22/19mm if I remember properly. The rear channel is 19mm and therefore gives 35% more pressure than the front. Which is why there's a fixed pressure bias valve. Front and rear channel progress linearly until 25bar is reached (around 380psi) at which point, the rear channel progresses at a slower pace than the front, resulting in less rear pressure. Just fine with stock MC as it tames the rear brakes. But if fitting same size pistons, then it fucks up the balance.

            So, what to replace the fixed bias valve with? I suggest fitting an adjustable one. Perhaps set to zero reduction to start with, and then to tune it according to needs.

            Brake harder. Go faster. No shit.




              Originally posted by LowR3V'in View Post
              crazy nobody has complained about it. fkn terrible.
              ah, ah, ah. I've been telling you guys for close to 15 years ;-) Nobody listened, except perhaps for Lance. ;-)
              Brake harder. Go faster. No shit.




                Lots of racers ditch that valve, and tune rearwith pad compound
                Originally posted by codyep3
                I hope to Christ you have looks going for you, because you sure as fuck don't have any intelligence.
                2001 silver/Blk 325 cabby. SOLD
                1988 Blk/Blk e30 factory wide body kit car SOLD
                1992 DS/BLK 325 m-tech II apperance pack cabby SOLD!
                2002 325xit Sil/blk. SOLD
                2012 328i xdrive touring. Wht/blk. SOLD
                2009 135 cabby. monacoblue/blk leather SOLD
                2007 Z4m coupe. Silver grey/black/ aluminum. 1of50
                2010 F650gs twin
                2016 M235i cabby. Mineral grey/Red leather


                  thanks lee u tha man.

                  ya i'll get one of those valves if my car still wants to nose dive like it did with the stock master.

                  what master do u use with your all around kit?

                  also, what i notice one of the mc, i think it's the e32 one, has like 3mm of a longer throw so looks
                  like the stock rod is alittle short for this mc. Is that a problem?
                  E30ve32 by jet jones, on Flickr
                  Last edited by LowR3V'in; 04-16-2019, 01:31 PM.


                    MC size doesn't depend on rotors size specifically but on if you run a front-only or a front and rear set-up. Because caliper piston sizes change depending on configs.

                    W/ front and rear kits. I suggest a 25,4mm MC if running a booster. Without booster, start at 19mm and see how it feels. Front caliper pistons shall be 1.625" or 1.75" while rear will be 1.125" or 1.25"

                    Front-only will work with stock MC because in most cases caliper pistons will be 1.25" for a stock bias (or 1.375" if a heavier engine is swapped)

                    Brake harder. Go faster. No shit.




                      ok after some days of driving the e32 master has done the job.
                      feels good.
                      modulation is stock like. it doesn't nose dive anymore.

                      braking hard coming in hot on a long turn just sorta kinda by a butt hair locks up the inside rear.

                      Fronts will lock up if needed and even on a hard panic stop they will lock up
                      but the thing is driver front locks up before passenger side so it's super controllable

                      rears have much more dust on them now

                      So ya, it did the job might need just a slice more of rear bias. oh so little bit more.
                      i've tried to over heat them like the stockers
                      no way its doing that anymore.

                      going to get the rear valve for sure.
                      thanks for the help lee. u a gem.
                      Last edited by LowR3V'in; 04-28-2019, 07:36 PM.


                        Glad it is working for you.
                        Brake harder. Go faster. No shit.