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    E21 brakebooster

    Hi,

    I'm Tom from Holland and we are building an E30 for trackdays. At the moment we have gathered most parts for the M50 swap but we're having a problem finding the right brakebooster. There is some sort of lack of them here. I have been reading this forum for a few months but haven't figured this out. Everybody on r3v talks about the E21 320i brakebooster, but how much is this one different from the 323i version?

    I hope someone can help me, thanks in advance.
    E30 Euro-S50B30 Tracktoy
    E30 M20B25 Drifttoy

    #2
    I bet they're the same. We got the 320i, you europeans got the 323i.

    I'd just use the 325ix booster.

    -Addis

    Doing something M50 related? -> http://www.addissimo.com
    On Myspace? ->http://groups.myspace.com/r3vlimited
    BF2142 SN = BillyGoose

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      #3
      Hmm, i have been reading about this offcourse but what I have read the most was about the e21 booster. I had the idea that the IX booster was harder to modify/place.

      (btw, nice site you have, but didn't find this on it :P )
      E30 Euro-S50B30 Tracktoy
      E30 M20B25 Drifttoy

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        #4
        Supposedly the 325ix brake booster fits perfect without any modifications, probably why Addis recommended it.
        253rwhp

        My Vids(OLD)
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          #5
          the booster may fit without modifications but wiht that booster you then have to have a remote res which you can use a oem parts out of v8 e39s?
          https://www.youtube.com/channel/UC-h...wE3UqwjjmaTrXg

          Comment


            #6
            If you have access to brake fluid line and threaded/barbed plumbing fittings, you can make your own remote res. setup.

            I recommend the ix booster because you dont have to modify the booster to make it fit, and it has more power assist. I had trouble locking my brakes up, as did another friend that used the e21 booster.

            The small amount of fabrication required to make the ix booster fit is well worth it imho.

            As soon as I get my fucking transmission from eurospeed (josh) I'll get my engine back in, and my brakes setup, then put it on my website so everybody can see whats up.

            -Addis

            Doing something M50 related? -> http://www.addissimo.com
            On Myspace? ->http://groups.myspace.com/r3vlimited
            BF2142 SN = BillyGoose

            Comment


              #7
              anyone have a diagram or some pics of what they did to modify the brake booster? Just wondering what I'm in for if I do 320i vs 325ix booster.

              I'm leaning toward the 320i booster due to price and availability, thanks in advance for the help

              dave

              Comment


                #8
                Originally posted by Addissimo
                I had trouble locking my brakes up, as did another friend that used the e21 booster.

                -Addis

                Have the same issue with my car. The rear will lock, but not the fronts.


                At the race track.

                Comment


                  #9
                  To compensate you guys should try using harder biting pads in the front and regular pads in the rear. That would help with the brake bias a little. But of course that's really just a band-aid.

                  What would be needed to keep the regular 325i booster? Does the manifold really hit it badly?

                  Comment


                    #10
                    I had to trim down the rearmost ribbing on the plenum for even the e21 booster to work. No way a non ix e30 one will fit.


                    At the race track.

                    Comment


                      #11
                      What do you guys mean by locking the brakes up? Go down the street and then stand on the brakes and count the skid marks? I used the E21 booster and my car stops fine, even when I've had to stomp on it hard the wheels will stop but bark some, no ABS on my car.
                      Eric
                      85 325e M50 and auto to manual transmission conversion...

                      Comment


                        #12
                        86325e,

                        can you walk me through your process of modifying the E21 booster to work. PM if you'd rather not post here, but whatever

                        Comment


                          #13
                          Originally posted by jrez
                          Have the same issue with my car. The rear will lock, but not the fronts.
                          that has nothing to do with the booster. i would check your master cylinder. it might be off bias due to an internal leak. the booster has nothing to do with brake bias....it simply assists pedal effort.

                          get some decent pads. if your running on something like pbr mmasters....dont expect to get abs kicking with any booster.

                          i have never had any trouble with pedal effort (or getting front abs to kick) with the 320 booster. street or track, no complaints.

                          the e21 booster has a longer pedal connecting rod. i have modified the rod successfully in two ways. 1. whack off the threaded end, shorten rod, reweld. stuff damp rags down againts the rod to keep heat from transfering down to the diaphram. 2. grind down the rod (unthreaded portion is thicker) evenly and die the threads. i had a difficult time getting the booster rod out of the diaphram, so throwing it on a lathe was not an option.

                          cheers, jason

                          Comment


                            #14
                            Originally posted by 1990m3
                            86325e,

                            can you walk me through your process of modifying the E21 booster to work. PM if you'd rather not post here, but whatever
                            Sure, this is what I did. I'm sure there are different or better ways of doing this but this is what I did. I take no responsibility if you F your stuff up. With that being said. You need to shorten the clevis fork rod by 75mm and rethread it.

                            Go ahead and make measurements of your E30 brake booster. Write down the length of the rod and the position of where the clevis fork is screwed on it. Then I used tape to mark the corresponding places on the E21 brake booster. I then securely braced the E21 booster without damaging it while I cut the rod down to where it needed to be.

                            Now you've probably already noticed that the rod diameter is a lot thicker than what the diameter of the threads were on the end of the rod. What you need to use is a tap and die set. Choose a diameter that will still safely fit in your clevis fork. This part you want to take it slow and do it right. You want the threads to be straight. Be sure to use some cutting oil. You also are going to have to go buy a nut for the back side of the clevis fork to hold it into place. You might want to write down the sizes of the taps and dies you have and then go find and buy the nut. I cut everything first and then had a hard time for some reason finding that size nut, ended up having to drive over to Arlington for it, but anyway. Boring out the clevis fork to your desired size is easy, just put that in a bench vise, take it slow, and make it straight and even. On the brake booster, I didn't have a vise that would work, so a friend came buy and we used vise gribs to hold the rod as straight as possible and to keep it from spinning as I cut the threads onto the rod.

                            Then clean everything up and all the shavings off. Screw you nut on to your clevis fork rod and then screw on your clevis fork. Look at the E30 brake booster measurements you wrote down and set the modified E21 booster to the same measurements. Once you put the booster in the car you might have to rotate the fork a half turn or so either way to get it perfect. You'll put the booster in after you get the engine in. The way my engine sits in the car its very close to the rear of the intake manifold but it clears. I didn't have to file any of the fins off. Doing this wasn't all that difficult at all, the hardest part making sure that the threads were done as straight as possible

                            Eric
                            Eric
                            85 325e M50 and auto to manual transmission conversion...

                            Comment


                              #15
                              Originally posted by Jason89i
                              that has nothing to do with the booster. i would check your master cylinder. it might be off bias due to an internal leak. the booster has nothing to do with brake bias....it simply assists pedal effort.

                              get some decent pads. if your running on something like pbr mmasters....dont expect to get abs kicking with any booster.

                              i have never had any trouble with pedal effort (or getting front abs to kick) with the 320 booster. street or track, no complaints.

                              the e21 booster has a longer pedal connecting rod. i have modified the rod successfully in two ways. 1. whack off the threaded end, shorten rod, reweld. stuff damp rags down againts the rod to keep heat from transfering down to the diaphram. 2. grind down the rod (unthreaded portion is thicker) evenly and die the threads. i had a difficult time getting the booster rod out of the diaphram, so throwing it on a lathe was not an option.

                              cheers, jason

                              Porterfield pads, SS flex lines, brand new master cyl, all new rotors and calipers.
                              I initially thought I might have too much grip with the "17's, as the rotors take on a blueish tinge, after hard braking.
                              It's not that it does'nt stop well, it's great, but I'd prefer to see the front lock up before the rears.


                              At the race track.

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