4 wheel drive upgrade

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    • June 4, 2018 at 3:40 pm #47918
      dogdoc
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        I found a drive shaft shop interested in helping me mod the 4 wheel system to some type of universal joint connection. I must bring him the shaft from the rear drive/transmission (where the aft section of the drive shaft attaches) to modify. I have removed the cover which holds the seal and can pull the shaft about a half inch forward but the bearing/shaft seems to stop at the front of the housing. Before I go further and cause problems thought I would ask for advice.
        thanks

      • June 4, 2018 at 4:52 pm #47919
        Bob Rooks
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          This is where a parts manual would really come in handy, and so would a picture. What make/model tractor are we talking about?

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        • June 4, 2018 at 5:16 pm #47920
          dogdoc
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            jinma 254 I will try to post pics

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          • June 4, 2018 at 5:18 pm #47922
            dogdoc
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              part is labeled 24 in pic above, moves about 1/2 inch forward, are the gears beveled? if so maybe they only can be pushed to the rear

            • June 4, 2018 at 7:10 pm #47923
              Bob Rooks
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                It looks like you will have to push the shaft through the rear far enough to remove the rear bearing, allowing the shaft to drop, and then remove the shaft through the front. The driver gear appears to be an interference. Do you know if both of those bearings are the same size?

                Is your shop going to weld on a sliding spline with a yoke and cross? That would be cool.

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              • June 5, 2018 at 3:21 pm #47927
                dogdoc
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                  pulled off rear cover and a tap with my hand pushed the shaft and rear bearing out the back. took the part to the shop doing the work and the guy who will actually do the job looked at it and was a little less optimistic than the fellow I saw yesterday. one concern was that whatever is done to the transfer case shaft still has to allow the cover and seal to slide over it for a seal. I was thinking maybe to fill the groves up by welding and then machining the shaft to a square or hex that would allow a standard universal coupler to slide on and pin in place with a roll pin. the front end should be easier as the shaft exposed from the front gear box is splined. would a square or hex in the rear be able to handle the required torque. also everything must fit inside the weldment cover or some kind of cover.
                  any thoughts would be appreciated
                  thanks

                • June 6, 2018 at 9:08 am #47930
                  Bob Rooks
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                    The only way I see that working is to replace a section of the #24 shaft with a splined shaft, and then use a clamped universal joint yoke like those used on PTO shafts. Which brings up a question; Why can’t you just adapt a category lll PTO drive line as a replacement?

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                  • June 7, 2018 at 7:30 am #47934
                    dogdoc
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                      bad news yesterday the guy at the shop gave me his big suggestion, a round bore universal with a keyway utilizing one of the grooves in shaft 24 for the key. it goes without saying I did not take his advice thanked him and brought all the stuff home. back to square one.

                    • June 7, 2018 at 12:58 pm #47935
                      Bob Rooks
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                        That might work ok too, but I don’t know the size of the #24 shaft or the HP of the tractor. A single keyway doesn’t have the efficiency of a spline.

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                      • June 7, 2018 at 5:26 pm #47937
                        dogdoc
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                          jinma 254/25hp, shaft is 24.75mm/.970 in

                          .70 in from groove to groove

                        • June 7, 2018 at 7:37 pm #47938
                          Bob Rooks
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                            dogdoc wrote:

                            jinma 254/25hp, shaft is 24.75mm/.970 in .70 in from groove to groove

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                            So, shaft itself is slightly less than 1″ diameter, and slightly less than 3/4″ diameter for the ball slots, and then subtract for a 5/16″ keyway. That doesn’t leave much meat.  According to my calculations, a shaft size of 1-3/8″ (34.9 mm) is required to transmit 20-30HP @ 1,800 r/m. I think you made the right call.

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