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Transmission Input Shaft and bearing- Question

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  • Transmission Input Shaft and bearing- Question

    Hello! Been a long time lurker and have a '91 M3 that i've owned for over 7 years.
    Car has 171k miles, engine has been rebuilt at 91k miles, the transmission as far as i know, is original.
    Back in 2013 i went through the entire car and replaced pretty much everything that needed replacing- all bushings, clutch/pp, rear main seal, input shaft seal, motor/trans mounts, hoses, ac compressor, etc. Cost a small fortune.

    Car has resided in Air Conditioned storage, probably drove it about 1k miles in the last 6 years. i know. Don't kill me.

    Recently took it from Houston to Austin for the Raduno Rally and had a blast with it and have recently been driving a bit more.

    Last week, noticed it left oil in my garage floor. Took it to my mechanic who took the car apart, long story short, the Input shaft seal is leaking.

    We have taken the transmission bell housing apart, and according to the mechanic, there is a groove that has been cut into the shaft from age, as well as the input shaft bearing has some play (prob moves about 2-3mm back and forth).

    Searched online for a new shaft and am coming up empty.
    Searched online for a new shaft brearing and its NLA (there's a seller in Germany with old stock at $500 + shipping).

    Question is-

    Am I better off getting a rebuilt unit from Metric Mechanic, or is it worth taking the transmission apart, sending the shaft to a shop to resurface out that groove and pay the $500+ for a new bearing? Gears are super smooth, never a hiccup (shifter and associated bushings were just recently refreshed). Will this be one of those 'while you are in there' things?

    Pics attached as well.

    Would LOVE to hear your thoughts!

  • #2
    Wow...good pictures....

    I see the groove in the shaft and all that, but are you 100% positive that the leak is coming from the shaft seal? I ask because it is very, VERY, VERY common for the 265 to leak around the joint between the throw-out bearing collar (the steel tube that goes around the input shaft) and the aluminum flange that the collar presses into. And this leak tends to look like the input shaft seal, but I would say it is actually much more commonly the joint I mention. They are dissimilar metals, and after all these years very few of them maintain a good oil seal.

    This problem is so common that before he gave up rebuilding Getrags, Jim Blanton had a modification for the 265 that changed the design of the collar/flange to correct the problem.

    Do you find that the throw-out bearing tube is full of oil when you take things apart?
    Last edited by Ironhead; 01-07-2020, 03:29 PM.

    Comment


    • #3
      Originally posted by Ironhead View Post
      Wow...good pictures....

      I see the groove in the shaft and all that, but are you 100% positive that the leak is coming from the shaft seal? I ask because it is very, VERY, VERY common for the 265 to leak around the joint between the throw-out bearing collar (the steel tube that goes around the input shaft) and the aluminum flange that the collar presses into. And this leak tends to look like the input shaft seal, but I would say it is actually much more commonly the joint I mention. They are dissimilar metals, and after all these years very few of them maintain a good oil seal.

      This problem is so common that before he gave up rebuilding Getrags, Jim Blanton had a modification for the 265 that changed the design of the collar/flange to correct the problem.

      Do you find that the throw-out bearing tube is full of oil when you take things apart?
      Thanks! The wonders of the Iphone 11Pro, the camera really is awesome!

      Interesting regarding the Throw out bearing collar. I actually didn't pay attention to that part of the assembly! I'll swing by in the am and look some more. I'm attaching a few parts diagrams. Would you mind pointing to which part you mention? I 'think' you mean Part #7 on the Bell Housing diagram. Let me know your thoughts?

      Thanks for your help!!

      Comment


      • #4
        In the top diagram, part #3 is the steel collar, that is supposed to be a press fit into part #2, the aluminum front case flange. In most transmissions, over the years, the parts have sort of loosened and lost the press fit and a leak forms from the joint between the dissimilar metals.

        In some 265s it is a major leak, in others just a drop here and there, but very few are bone dry there.

        There is no way I know of to fix it, other than to replace the parts, and sometimes even that doesn't work completely. It's just a bad design.

        Comment


        • #5
          Interesting! I dont remember seeing oil seeping out from that area, but am not 100% sure. I'm definitely checking in the am. Will report back! Sucks that so many of these parts are now NLA too.. Thanks again! I'll get back to you in the am.

          Comment


          • #6
            If the small groove on the input shaft caused by the oil seal is the cause of the oil leak, the fix is similar to the same oil leak at the rear main seal. To stop the leak install a new oil seal just a little less than full into its place so it rides on a different place on the shaft than where the groove is. And put some grease on the ID of the seal before you install it so it doesn't start dry, until some oil gets there by running.

            Comment


            • #7
              Hi,
              When the front cover was bolted up before disassembly did the input shaft have the 2-3mm of end float or is only there when the front cover is off.
              I am wondering if the play is between the inner and outer races ie ball bearings or outer race and case, some bearings are grade 1, 2 or 3 and 3 being the most play from new and from memory I think 3 is what they have from factory.

              Interesting you have roller bearings at the layshaft I read that metric mechanic were doing that.
              I also read they removed all the end float from both shafts instead of the factory end float which in time turned to clatter when hot and idling. I take it there was no gasket in the front cover just sealed on if that was the case assemble it how it was.

              Polish the shaft with 600 grit wet and dry and then reassess to see if it looks okay and like Ron mentioned installing the new seal in different place.

              Measure how far the old one is down the tube for reference prior to removal.

              E30 M3 1987
              Mini Clubman GT
              BMW E36 323 Msport
              Toyota Corona
              KTM 200EXC
              Honda CB50 (1979)

              Comment


              • #8
                Originally posted by nsubre View Post
                If the small groove on the input shaft caused by the oil seal is the cause of the oil leak, the fix is similar to the same oil leak at the rear main seal. To stop the leak install a new oil seal just a little less than full into its place so it rides on a different place on the shaft than where the groove is. And put some grease on the ID of the seal before you install it so it doesn't start dry, until some oil gets there by running.
                Good point. Let me ask the mechanic if this would be a good (and easy!) option.

                Comment


                • #9
                  Originally posted by Dave @nz View Post
                  Hi,
                  When the front cover was bolted up before disassembly did the input shaft have the 2-3mm of end float or is only there when the front cover is off.
                  I am wondering if the play is between the inner and outer races ie ball bearings or outer race and case, some bearings are grade 1, 2 or 3 and 3 being the most play from new and from memory I think 3 is what they have from factory.

                  Interesting you have roller bearings at the layshaft I read that metric mechanic were doing that.
                  I also read they removed all the end float from both shafts instead of the factory end float which in time turned to clatter when hot and idling. I take it there was no gasket in the front cover just sealed on if that was the case assemble it how it was.

                  Polish the shaft with 600 grit wet and dry and then reassess to see if it looks okay and like Ron mentioned installing the new seal in different place.

                  Measure how far the old one is down the tube for reference prior to removal.
                  Play with cover on/off- good question. let me see if we can put that cover back on. i'll also take a video of the actual play and post it here.
                  Correct- no gasket, just some liquid gasket that was used there (clearly someone was in the transmission before?)
                  Polishing- Hmm. the mechanic's thought was to take it to a machine shop, i'd love to avoid taking this thing fully apart, so this could be an option to explore..

                  Comment


                  • #10
                    So here are a few more pics. Ironhead here are pics of the steel collar and assembly (parts #2 and #3). No oil on the, just grease from the throwout bearing.

                    Pic of the seal on the shaft as well...

                    Dave @nz, with the front cover back on, there isn't much play.

                    Here is the link to the video I took of the play
                    https://photos.app.goo.gl/fVDWti1JBPECuSgH8

                    Comment


                    • #11
                      The left and fight play of the shaft is normal in my opinion perfectly serviceable and no need for further action, if the shaft was going in and out 2-3mm that would be a concern.

                      If the shaft was removed a machinist would mount it in the lathe and polish the shaft with wet and dry paper to smooth, what I am suggesting is polish the shaft just as it is now with wet and dry to smooth out the sharpness of the groves probably won’t get the groves out but you will be pleasantly surprised what you can achieve in a few minutes.













                      E30 M3 1987
                      Mini Clubman GT
                      BMW E36 323 Msport
                      Toyota Corona
                      KTM 200EXC
                      Honda CB50 (1979)

                      Comment


                      • #12
                        Originally posted by Dave @nz View Post
                        The left and fight play of the shaft is normal in my opinion perfectly serviceable and no need for further action, if the shaft was going in and out 2-3mm that would be a concern.

                        If the shaft was removed a machinist would mount it in the lathe and polish the shaft with wet and dry paper to smooth, what I am suggesting is polish the shaft just as it is now with wet and dry to smooth out the sharpness of the groves probably won’t get the groves out but you will be pleasantly surprised what you can achieve in a few minutes.
                        Dave, good point. A bit concerned with metal filings/flakes entering the bearings. I'll ask the mechanic about this option tomorrow for sure. will definitely save a lot of hassle of disassembly for sure...

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