m20 crank sprocket, on m52 crank need to modify or should slip on?

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  • kickinindian
    R3VLimited
    • Jan 2012
    • 2327

    #1

    m20 crank sprocket, on m52 crank need to modify or should slip on?

    so like the title states should the m20 timing belt sprocket slide onto the m52b28 keyway after the crank spacer or does it need to be modified i kinda held it up to each other today and it looks like the sprocket side is too small
  • digger
    R3V Elite
    • Nov 2005
    • 5926

    #2
    should basically slip on to get it started then go all the way with some effort you can use the bolt to screw it in from memory, no need to modify the gear itslef.

    make sure the mating surfaces are immaculate, no dents etc that will score the surface

    usually use a puller to remove it so its not a sloppy fit that can usually be done by hand
    Last edited by digger; 12-02-2014, 12:15 PM.
    89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

    new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

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    • kickinindian
      R3VLimited
      • Jan 2012
      • 2327

      #3
      thanks digger! and i use the m20b25 crank bolt and conical washer/spacer too?

      so it would be oil seal spacer>sprocket>conical washer>crank bolt. correct?

      Comment

      • redlightpete
        Wrencher
        • Mar 2012
        • 260

        #4
        You'll need to cut the stepped section off the conical washer because the crank snout is a little too long. Also the m20 crank bolt is too long. The m52b28 one is shorter and works.

        Comment

        • kickinindian
          R3VLimited
          • Jan 2012
          • 2327

          #5
          damn it i bought the crank without the bolt could i cut my m20 one down and that would work?

          Comment

          • digger
            R3V Elite
            • Nov 2005
            • 5926

            #6
            a unmolested bolt is about $20 or less from other places if you get stuck

            http://www.pelicanparts.com/catalog/...ENGMAN_pg1.htm

            i thought the m20 one was too short but could be wrong. m20 on LHS one i used for S52 crank on the right

            Last edited by digger; 12-02-2014, 09:51 PM.
            89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

            new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

            Comment

            • redlightpete
              Wrencher
              • Mar 2012
              • 260

              #7
              Maybe I'm remembering the bolt length backwards. Just make sure you have a reasonable amount of thread engagement and that you're not running out of thread depth before you fully clamp the parts together.

              Comment

              • digger
                R3V Elite
                • Nov 2005
                • 5926

                #8
                updated pic to the correct one
                89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

                Comment

                • kickinindian
                  R3VLimited
                  • Jan 2012
                  • 2327

                  #9
                  okay so i will have to get the m52 one then oh well good to know

                  Comment

                  • MR 325
                    Moderator
                    • Oct 2003
                    • 37827

                    #10
                    Yes you will need the 24v crank bolt and you will need to machine the washer down to sit correctly.
                    BimmerHeads
                    Classic BMW Specialists
                    Santa Clarita, CA

                    www.BimmerHeads.com

                    Comment

                    • kickinindian
                      R3VLimited
                      • Jan 2012
                      • 2327

                      #11
                      putting this here for later

                      m52 crank bolt #11211720633

                      Comment

                      • 16vCorey
                        Member
                        • Jan 2013
                        • 96

                        #12
                        Yep, you have to use the M52 bolt. I didn't have to do anything to the washer when I built my M20B28, so I'm not sure what that's about.

                        Comment

                        • MR 325
                          Moderator
                          • Oct 2003
                          • 37827

                          #13
                          Originally posted by 16vCorey
                          Yep, you have to use the M52 bolt. I didn't have to do anything to the washer when I built my M20B28, so I'm not sure what that's about.
                          It will work without modifying the washer but it won't sit currently.

                          What crank spacer did you use?
                          BimmerHeads
                          Classic BMW Specialists
                          Santa Clarita, CA

                          www.BimmerHeads.com

                          Comment

                          • mikerob97
                            Advanced Member
                            • Jul 2010
                            • 140

                            #14
                            I am looking for information on where to buy the proper cranksshaft spacer and properly machined washer - does anyone know where I might find one?

                            Thanks in advance for any help.
                            Mike
                            Cary, NC
                            Current Rides
                            1991 325iC - For Sale
                            2006 M3 Cabriolet
                            Past Rides
                            2000 323i Touring - Daily Driver
                            1994 325is (S50) - Fast Car
                            1998 Z3 - Fun Car
                            1986 325e (i engine conversion)
                            1969 Mustang Mach 1

                            Comment

                            • abit
                              E30 Addict
                              • Jul 2011
                              • 416

                              #15
                              here is info about washer machining down: (as far as I remember, I even took more than 1,25mm off, by using the same crank spacer as he)


                              spacer dimensions:
                              http://instagram.com/mundieriss
                              my 88' m20b30 HERE!

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