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M20b25 flywheel/Transmission problem

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    M20b25 flywheel/Transmission problem

    Alright so my motor is out the car and i have the m20b25 from a 89 325i with new "i" clutch kit with the original resurfaced flywheel mounted to a late ETA 87 transmission with the reference sensors and large output flange. Before i put it in the car, will the clutch engage with the 325i TOB since im using the eta trans on a 325i clutch setup with single mass flywheel? since my original motor had a dual mass flywheel will the single mass fw work? Or am i going to have to use a different TOB? I searched everywhere and couldnt find a clear answer because some people are saying i will need a 323i TOB, some others are saying the 325i will work. Also i measured off the bellhousing from the slave and its 6.5 inches. Which is the same on the 325i g260. Im confused. How could they be the same if the original trans i have from the eta had a dual flywheel setup and the 325i trans has a single. they are obviously different in thickness. I just dont want to install the motor in the car then later realize that the clutch wont engage. and then ill have to tear it all apart.
    Last edited by danielpak_ek9; 03-24-2017, 04:13 PM.

    #2
    to the top

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      #3
      Why not make a 2.7L stroker? If you have the e bottom and the I head and intake?

      Not sure on the trans though.
      1987 325is 2.8L Stroker Turbo "Little Pickle aka The Green Turbo Sled"

      Comment


        #4
        hmm you gotta be careful when mixing and matching.

        Have a read in this thread about my woes. Someone comments after me with some good info.



        if your 325e does have the much thicker dual mass flywheel, I reckon if you use your m20b25 with its single mass flywheel, your clutch throw out bearing wont move foward enough to completely disengage the clutch. I think there is a solution around that involves a different throw out bearing that has a spacer built in, or you can weld a bit on the end of your clutch slave push rod.

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          #5
          I think you should be able to swap everything as a unit. By that I mean the 325i flywheel and matching clutch kit. On most eta cars, the crank/flywheel sensor is located on the transmission bell housing, which gets a reading off the eta specific flywheel. If you were keeping the Eta engine/electronics, but used the "i" flywheel, you would need to swap the reference slug over.

          Since you're converting to an m20b25 (with the engine harness?), then the crank sensor sits up front, so the engine doesn't care what transmission & flywheel setup you're using because it doesn't need a reading off the flywheel. It's a good idea to plug the hole to keep debris out on the Eta trans.

          Here's a helpful link to explain some of the differences:

          http://www.bimmerforums.com/forum/showthread.php?1658129-ETA-flywheel-to-I-Flywheel-conversion
          Last edited by mtech325; 02-09-2017, 11:13 AM.

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            #6
            There are different depth transmissions, and I THOUGHT that all M20's had the same
            block/crank flange dimensions.

            So you keep the flywheel/clutch/pp/throwout with the trans, and,
            for example if you want to ditch the dual mass, you have to make changes
            to the clutch/flywheel stack to get the throwout bearing in the right place.

            But I've only worked on a sample of 2, in depth...

            t
            now, sometimes I just mess with people. It's more entertaining that way. george graves

            Comment


              #7
              Originally posted by Chris Spiegl View Post
              Why not make a 2.7L stroker? If you have the e bottom and the I head and intake?

              Not sure on the trans though.
              not really sure on the condition of the bottom end and didnt want to deal with it

              Comment


                #8
                We just got done doing this after running into some issues.
                We were running a mid year trans with "I" FW and clutch setup. Apparently our trans had the deeper bell so the TOB would t engage the clutch. Had to pull the trans out and replace with the 320i TOB.
                If I understand your question correctly, your just swapping the motor so everything should bolt up fine. AFAIK the block flange and mounting is all the same. Ours was also a 87 but motor was from a 89 and trans is unknown.

                Comment


                  #9
                  I put an eta 5spd on my cabrio and used a stock "I" clutch kit and replacement lightweight I flywheel. We just clipped the sensor wires and left the sensors to plug the holes
                  Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

                  https://www.r3vlimited.com/board/sho...86#post4944786
                  Alice the Time Capsule
                  http://www.r3vlimited.com/board/showthread.php?t=360504
                  87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

                  Comment


                    #10
                    Originally posted by jeffnhiscars View Post
                    I put an eta 5spd on my cabrio and used a stock "I" clutch kit and replacement lightweight I flywheel. We just clipped the sensor wires and left the sensors to plug the holes

                    Thanks! just what i needed to know. What throw out bearing was used? ETA? or I

                    Comment


                      #11
                      Full stock "I" clutch kit
                      Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

                      https://www.r3vlimited.com/board/sho...86#post4944786
                      Alice the Time Capsule
                      http://www.r3vlimited.com/board/showthread.php?t=360504
                      87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

                      Comment


                        #12
                        Originally posted by Supratreo View Post
                        We just got done doing this after running into some issues.
                        We were running a mid year trans with "I" FW and clutch setup. Apparently our trans had the deeper bell so the TOB would t engage the clutch. Had to pull the trans out and replace with the 320i TOB.
                        If I understand your question correctly, your just swapping the motor so everything should bolt up fine. AFAIK the block flange and mounting is all the same. Ours was also a 87 but motor was from a 89 and trans is unknown.
                        Yup i wasnt exactly sure if my 325i parts car ran and no way to start it without transmission so i decided to just put the 325e transmission on with the 325i clutch and flywheel. I also used the eta TOB and i had that same issue you had.. the xlutch didnt engage. the TOB has to be from the I not the 325e. But i got the motor running which was my main motive and will be getting the 325i clutch kit with bearing. All my questions are answered. Thanks to you all for your help and responses!

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                          #13
                          New question! to the top.

                          Comment


                            #14
                            bump bump still searching.

                            Comment


                              #15
                              ...for what?

                              t
                              now, sometimes I just mess with people. It's more entertaining that way. george graves

                              Comment

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