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  • I need your opinions

    I have a shaft out of a transmission that has a gear riding on it. The gear has a bronze bushing in it. The shaft is worn where the gear rides on it. The shaft diameter where the gear rides was 1.000". It is worn to .975". How would you repair this? The spline next to the journal is .964"OD. I am reluctant to weld it up and machine it down for fear of changing the temper of the spline or adjacent gear.I thought about making a press fit sleeve. Or I may be able to get a smaller ID bushing and make the shaft fit the bushing. According to my customer these parts are not available separately- the manufacturer wants to sell a complete transmission.In the attached photos the white X identifies the worn journal.
    http://img.photobucket.com/albums/v6...r/IM002497.jpg
    http://img.photobucket.com/albums/v6...r/IM002498.jpg
    http://img.photobucket.com/albums/v6...r/IM002499.jpg

  • #2
    Hard chrome plating?

    Comment


    • #3
      Worn Shaft

      Chances are that the shaft hardening (if any) has been compromised so I'd be reluctant to go any smaller for a working surface. It may have been too soft to start with, hence the failure.

      What are the chances that you can bore the gear and use a bushing with a thicker wall? If my calculations are correct, taking the shaft down to the spline diameter would allow only 0.018" wall on your new sleeve if you bring it back to the 1.000" diameter.

      Say a 0.035" wall sleeve (roughly double the 0.018") and a new thicker wall bushing to accommodate it would give a long life fix. Or if the bronze bush has a thick enough wall, just bore it out to fit what ever shaft diameter you settle on.

      I certainly wouldn't press the sleeve on. I think I'd allow 0.001" to 0.0015" tight fit, heat it up and shrink it on. Allow enough wall thickness to turn it back to whatever final shaft O.D. you decide upon.

      Comment


      • #4
        I assume the bronze bushing is smoked too? Make a new bronze bushing to press fit in the gear at .970 ID and clean up the shaft at whatever the RC4 or RC5 running tolerance of .970 is.
        For RC5
        Shaft would be .970 -.0016/-.0024
        Bushing would be .970 +.0012

        Press the new bushing in before boring it.
        Last edited by Rusty Marlin; 01-30-2008, 07:14 PM.
        Ignorance is curable through education.

        Comment


        • #5
          Its been pretty hot, so the heat treat is probly gone.

          If not then I might grind both surfaces and find a suitable needle bearing.

          I would also check the material and heat treatment to be sure that i wont be damaged by the bearing. I might go as far as to press a race into the gear for the bearing to ride on the OD.

          I would think that if I had a gear box shop (traction products in costa mesa) build them from scratch would be around a grand.

          Bushings suck.
          Last edited by steverice; 01-30-2008, 07:46 PM.
          "the ocean is the ultimate solution"

          Comment


          • #6
            I doubt it was hot enough to lose much hardness. That takes 800 to 900 degrees. That looks like burnt oil stains to me. Clean it up to a smaller diameter and make a bushing to fit. You will find out real quick how hard it is when you try to turn it.
            Free software for calculating bolt circles and similar: Click Here

            Comment


            • #7
              Shaft sleeve

              A "shaft sleeve" may be a viable option.

              They work very well.

              http://www.durasleeve.com/shaftsleeves.html

              http://www.durasleeve.com/oursleeve.html

              http://www.google.com.au/search?hl=e...e+Search&meta=

              I hope it helps.

              Comment


              • #8
                Just another idea for what it's worth- you aren't going to want to reduce the diameter of the shaft very much at all, but if you have to reduce it to less than the diameter of the splines, then you could make a bushing in two halves. You'd probably have to start with two bushings, then cut each one for a slightly larger than half piece. Trim as required to make the pair a fully round bushing again. Press them into the gear. Turn a piece of scrap to the same diameter as the re-worked shaft, then use that to aid in boring the bushing to a fit. Press the bushing halves out of the gear, assemble them over the shaft, then press the gear on again. You may need some temporary shims between the bushing pieces and the gear on the shaft while pressing the other gear on.

                It doesn't appear that there's much room to bore the gear out for a thicker bushing, so hopefully you can get a thin enough one in there without mashing it, in the event that your repaired shaft still has a larger diameter there than the splines.

                One thing I would not do it try to run rollers on the repaired shaft. Needle rollers are nice and all, but won't last long unless that section of shaft is sized very closely, hardened, ground, and polished. If the needle roller bearing is complete with inner and outer races, that's another story, but again I don't think there's room there for that.
                I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                Comment


                • #9
                  The shaft is probably scarry expensive. I would turn the worn area down about .030" on a side, heat the shaft up and weld it and turn it to size. Then send it out to have it rehardened.

                  You would have to test it for hardness before working on it. I would try to weld it with something that can be hardened. It would take some checking to find out what to weld it with.

                  If you weld it while it is turning the stress should be even and it may not warp. It can be straightened.

                  We used to do stuff like that all the time.
                  It's only ink and paper

                  Comment


                  • #10
                    Take to your local machine shop. Get shaft metal sprayed the turn are grind back down to size . Good as new them. Every day occurrence.
                    Every Mans Work Is A Portrait of Him Self
                    http://sites.google.com/site/machinistsite/TWO-BUDDIES
                    http://s178.photobucket.com/user/lan...?sort=3&page=1

                    Comment


                    • #11
                      No brainer solution, send it to John Stevenson.

                      Comment


                      • #12
                        Get shaft metal sprayed...
                        Will someone expand on this a little please?

                        Comment


                        • #13
                          Metal spray(ing)

                          Get shaft metal sprayed...
                          Originally posted by tony ennis
                          Will someone expand on this a little please?
                          Tony.

                          Try these.

                          As Lane says, it works really, really well.

                          You can choose the process/metal and consequently the way you finish it off.

                          http://www.gordonengland.co.uk/cws.htm

                          http://www.metalpowders.com.au/spray...s/plsmhvof.htm

                          http://www.plasdip.com.au/metal.htm

                          http://www.google.com.au/search?hl=e...e+Search&meta=

                          Comment


                          • #14
                            Thanks for the input everyone.I have bushings ordered with the correct OD and smaller ID. I am going to use my toolpost grinder to clean up the journal then bore the bushing to fit the shaft.I'll be sure to post photos when I do the job.

                            Comment


                            • #15
                              Originally posted by jcarter
                              I have a shaft out of a transmission that has a gear riding on it. The gear has a bronze bushing in it. The shaft is worn where the gear rides on it. The shaft diameter where the gear rides was 1.000". It is worn to .975". How would you repair this? The spline next to the journal is .964"OD. I am reluctant to weld it up and machine it down for fear of changing the temper of the spline or adjacent gear.I thought about making a press fit sleeve. Or I may be able to get a smaller ID bushing and make the shaft fit the bushing. According to my customer these parts are not available separately- the manufacturer wants to sell a complete transmission.In the attached photos the white X identifies the worn journal.
                              http://img.photobucket.com/albums/v6...r/IM002497.jpg
                              http://img.photobucket.com/albums/v6...r/IM002498.jpg
                              http://img.photobucket.com/albums/v6...r/IM002499.jpg
                              The only option I can see is to turn if soft enough or grind down the fit and spray weld it then grind to size. regular welding wouldn't be an option if it is a hardened shaft, which it probably is. hope this helps Peter
                              The difficult done right away. the impossible takes a little time.

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