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Metric Mechanic M52-M20 crank spacer loose?

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    Metric Mechanic M52-M20 crank spacer loose?

    Just got an M52 crank back from the machine shop. I asked for the MM spacer to be installed, which they did.

    Issue is, the spacer is loose. I can turn/move it with my fingers. If the woodruff keys weren't installed, I imagine I could slip it right off.

    Is this normal? I'd expected it to be firmly in place with zero movement once installed.

    I can understand how, when bolted up behind 325# of torque, it would be sandwiched in place...but this doesn't seem right, right?

    #2
    Removed the woodruff keys.

    The spacer slides easily up/down the crank nose until about a spacer-width from the end, where it becomes tight and cannot easily be removed (without using a puller or similar).

    Is the M52 crank nose usually tapered?

    Comment


      #3
      thats normnal its a clearance fit, when you tighten the f*** out of the M18 bolt its held by friction from the preload just like the gear itself

      its not tapered normally
      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


        #4
        So if the nose isn't supposed to be tapered, the only thing I can think is that the machine shop linished it, and somehow managed to fuck that up...resulting in a tapered nose.

        Bottom line, is this crank now trash or will the 325# keep the spacer in place for the lifetime of the engine? It's gonna sit on/behind the seal and be swimming in oil from day one.

        I get that, once installed, the spacer will have very low resistance/friction acting on it - just the lip of the oil seal and plenty of lube/engine oil so...it might be ok???

        I don't recall the M52 crank that's in the current engine having a similarly loose spacer, but that was a kit from IE, so they most likely used their own spacer.

        Originally posted by digger View Post
        just like the gear itself
        But the gears are also supported by the 2 woodruff keys + keying on the inner timing gear...?
        Last edited by Lugnuts; 02-05-2020, 03:28 AM.

        Comment


          #5
          Does it slide all the way back to the shoulder by hand? When we make spacers we cut the ID to +/- 0.000" and they have to be heated slightly to get on.
          john@m20guru.com
          Links:
          Transaction feedback: Here, here and here. Thanks :D

          Comment


            #6
            Originally posted by ForcedFirebird View Post
            Does it slide all the way back to the shoulder by hand? When we make spacers we cut the ID to +/- 0.000" and they have to be heated slightly to get on.
            I hope you guys modified your spacers. Remember I reached out to you with the issue: the inside chamfered edge was too small and there was a gap between the spacer and the crank shoulder. It was a bitch to remove again due to the press fit. Gap was tiny, almost unnoticeable but the feeler gauge confirmed it. If not flush against the crank, all that bolt torque would be concentrated on the spacer chamfer edge/crank inside corner ...if that makes any sense.I think you should go MM style. Will also let you finish the seal surface properly from the get go. It was very rough and I had to finish it as not to rip up the seal lip.

            Sent from my iPhone using Tapatalk
            Last edited by zaq123; 02-05-2020, 08:04 AM.

            Comment


              #7
              Originally posted by Lugnuts View Post



              But the gears are also supported by the 2 woodruff keys + keying on the inner timing gear...?
              woodruff key is working with all that torque from the crank bolt....that's what is keeping the gear in place, the combination of the two. Seal spacer has no large amount of rotational force on it, whatever the seal lip can produce (almost nothing). Crank Bolt torque will sandwich the spacer between the crank and the timing gear...more than enough to keep it firmly in place

              Comment


                #8
                Yours was the only one. Not sure what happened, we now make them with an oversized chamfer The key is unnecessary, it's only there to align timing - and that's why I have had to repair 3 or 4 cranks over the years when people don't tighten the crank bolt enough. The washer also needs to be modified for a 24v crank, or it bottoms out on the crank snout before holding the timing belt gear in place, then the key wiggles back/forth and hogs out the key way. I came up with e repair in the car using a standard square key. When e30 Motorworks were around, they would use a thin washer to take up the slack, but I have seen one of those slip. Best to shave the raised portion on the bottom/back of the washer.
                john@m20guru.com
                Links:
                Transaction feedback: Here, here and here. Thanks :D

                Comment


                  #9
                  Originally posted by Lugnuts View Post
                  So if the nose isn't supposed to be tapered, the only thing I can think is that the machine shop linished it, and somehow managed to fuck that up...resulting in a tapered nose.

                  Bottom line, is this crank now trash or will the 325# keep the spacer in place for the lifetime of the engine? It's gonna sit on/behind the seal and be swimming in oil from day one.

                  I get that, once installed, the spacer will have very low resistance/friction acting on it - just the lip of the oil seal and plenty of lube/engine oil so...it might be ok???

                  I don't recall the M52 crank that's in the current engine having a similarly loose spacer, but that was a kit from IE, so they most likely used their own spacer.



                  But the gears are also supported by the 2 woodruff keys + keying on the inner timing gear...?
                  The MM is a quality piece, as long as its concentric and sits flat against the crank you'll be sweet the lip seal will work and function fine. you can always mic the snout its probably not far out if you have 0.005 mm clearance then its going to be tight in spots as the snout is probably more variable than that. ive seen them bulged at the very end and that is fixable. i usually put a bit of sealant goop in the chamfer / radius to stop the oil leaking behind and through the snout/collar gap even though it probably wouldn't as the metal to metal flat face is a decent seal already
                  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


                    #10
                    Originally posted by ForcedFirebird View Post
                    Does it slide all the way back to the shoulder by hand? When we make spacers we cut the ID to +/- 0.000" and they have to be heated slightly to get on.
                    At the shoulder end, I can turn the spacer by finger. It will also slide up flush to the end of the nose, where it becomes tight and won't come off w/o using a puller.

                    I spoke with Jim @ MM this morning and he suggested using one or two light coats of paint either on the crank nose, or the inside of the spacer just to centre it. He also reassured that with 325# of torque holding it in place, it ain't going anywhere - it wouldn't go anywhere with a lot less torque applied.

                    The amount of radial play in the spacer when up against the shoulder (where it would live once installed) is really really really small - I don't think I can feel any rocking/sideways movement. The paint may not even be necessary.

                    Thanks for the responses everyone - false alarm, my bad.

                    Edit: I bought the spacer kit from MM, so I have the longer bolt + machined washer with the shallower step on the back.
                    Last edited by Lugnuts; 02-05-2020, 06:06 PM.

                    Comment


                      #11
                      paint is not necessary, the radial runout tolerance is a fair bit for the oil seals. if its tight at the end then its the bolt that has swedged it a smidge and fairly common, just get some fine wet and try and smooth burrs etc
                      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


                        #12
                        Originally posted by digger View Post
                        the radial runout tolerance is a fair bit for the oil seals
                        I was focused on the centering being done to avoid introducing vibrations, but now that I take a minute to think about it - I see your point. Having an off-center spacer pushing on the seal lip, causing a leak is the more likely/annoying scenario. Thanks for explaining that!

                        Comment


                          #13
                          yeah the out of balance will be negligible, the permissible shaft runout tolerance i saw were something like 0.10 mm for a high rpm shaft where as the two (2) MM sleeves I've used would be at most 0.02 mm clearance.
                          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

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