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in-frame gearbox rebuild

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  • in-frame gearbox rebuild

    I had a "groan" when I engaged the clutch end of last year so I installed a new throwout bearing...but that didn't stop the noise. I also have oil leaking from somewhere in the back of the primary drive so now after 1000 miles this spring I decided it was time to fix it. First decision was to see how big a hassle it was going to be to leave the gearbox attached to the motor and left in the frame... it's really not a problem:

    top off.jpg

    At some point the primary chain has been dragging on the case... not good:

    case wear.jpg

    I have some slight motion in the clutch basket as it sits on the main shaft, but I'm not certain if it's enough to worry about? I also discovered the clutch hub nut on the inside was finger tight only... so maybe that's what caused the groan and case wear? At any rate, the bearings will be replaced...they had a little drag on them. I've got a clutch basket bushing coming but if I don't need to put a new one in that will keep me from having to purchase another reamer... which would just be another of those one-time use tools!

    clutch hub bushing.jpg
    Last edited by pisten-bully; 07-11-2021, 12:22 PM.
    Pisten Bulley is Harry Roberts in Vermont.

  • #2
    I dont know how much is slight motion,but you could put the shaft in a vice and see how much back and forth the teeth move.There is only about .020 space on each side of the gen. drive to the inside primary chain link if its centered.
    The last bushing I did was from greer and it fit perfect after a quick pass with a brake cylinder hone for an in house job.
    The disadvantage of doing it place is not being able to heat the case to 250 and easily remove and install the bearings,and watch the cluster shaft
    right side bushing fall out.
    Have fun
    Tom

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    • #3
      Ouch! Major undertaking!! But it looks like you have it well underway. Any problems getting the bearings out cold?
      If bearing install is easier with case pre-heated might be something to consider. I am all about easy over force.

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      • #4
        Originally posted by tfburke3 View Post
        I dont know how much is slight motion,but you could put the shaft in a vice and see how much back and forth the teeth move.There is only about .020 space on each side of the gen. drive to the inside primary chain link if its centered.
        Thanks Tom, I'll do that and see how much it moves. The chain marks on the bottom of the case are old, as I found when I cleaned up the case and found old sealant in them.

        To get the bearings out, the clutch side was a bear, but I'm patient. First with the heat gun on the case, nuthin' moved...but I don't smack it hard. More heat, nuthin'...so I punched out the inner race and balls so I was only dealing with the outer race. I hit the outer race with the welder (even though I've never had that work for me) ...and nuthin'. Hit the race with a Dremel and cut a groove in it, then with a small 3" chisel I was able to crack the race on the groove and it came out. Time spent on clutch side bearing: 1.5 hours+.

        For the sprocket side I used the heat gun for 15+ minutes, and with the first or second hit with the drift it started to move. Few more hits and it was out. Time spent on sprocket side bearing: 20 minutes.

        Pisten Bulley is Harry Roberts in Vermont.

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        • #5
          Thanks for the update. Please let me know how the bearing installation goes.

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          • #6
            Originally posted by pisten-bully View Post

            Thanks Tom, I'll do that and see how much it moves. The chain marks on the bottom of the case are old, as I found when I cleaned up the case and found old sealant in them.

            To get the bearings out, the clutch side was a bear, but I'm patient. First with the heat gun on the case, nuthin' moved...but I don't smack it hard. More heat, nuthin'...so I punched out the inner race and balls so I was only dealing with the outer race. I hit the outer race with the welder (even though I've never had that work for me) ...and nuthin'. Hit the race with a Dremel and cut a groove in it, then with a small 3" chisel I was able to crack the race on the groove and it came out. Time spent on clutch side bearing: 1.5 hours+.

            For the sprocket side I used the heat gun for 15+ minutes, and with the first or second hit with the drift it started to move. Few more hits and it was out. Time spent on sprocket side bearing: 20 minutes.
            not sure why you dont pull the 5 bolts ,support the motor,and just lift out the case,your almost there already.
            Kiwi has a trans rebuild video that you may find helpful.
            He recommends to remove the rt.countershaft bushing even on a nos case and fitting oversize as they are to known to spin and benefit from a tighter fit.
            Often they fall out when heating to install bearings.
            Good time to check the motor and trans flange alignment,along with sprocket alignment.
            Tom

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            • #7
              ...glad I ordered a new clutch hub bushing, the wobble is .012 or so:

              free play.jpg
              I'm just doing it in frame because I wanted to see if it can be done! (Plus....alignment was all good before so I didn't want to take the chance of screwing it up and creating more work... it's riding season and the faster it gets done the sooner I can ride again )
              Pisten Bulley is Harry Roberts in Vermont.

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              • #8
                Pisten
                You mentioned the clutch hub nut was only finger tight. Was the Tab washer bent over? On re-assembly would you consider using Lock-tite with Tab washer?

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                • #9
                  Paul, that's right and partly I suspect because the locking washer was a rather flimsy multi-fingered washer where the fingers didn't do much holding (you can see it in the background of one of the picture showing mainshaft and clutch together). Loctite for sure!
                  Pisten Bulley is Harry Roberts in Vermont.

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                  • #10
                    Howdy sir,

                    The groan you here is most likely hear is the clutch basket slightly aligning itself on clutch take up. The higher the friction coefficient (Qua sintered bronze, anything with carbon fiber or similar) of clutch plates used the more likely noise on engagement.

                    When viewing the basket in cross section, its bushing is offset far inboard into the transmission case leaving the outer compartment containing the heavy clutch plate assembly unsupported. If that bushing is worn, even with the worm/throw out bearing pulling it somewhat into alignment upon disengagement the “wobbling” basket will align itself on clutch take up with the plates slightly offset causing chatter. Some have “remedied” this annoyance by tightening their primary drive which dulls the chatter but is merely a bandaid.

                    Not off topic, but related, some have eliminated first gear engagement clash at rest by tightening their final drive chain. No good, it’s entrapping the trans main shaft with the sprocket driver gear bushing, which only turns at 1:1 in high gear, otherwise wearing out prematurely in 1st and 2nd.
                    Cheerio,
                    Peter
                    #6510
                    1950 Vincent - A Red Rapide Experience

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                    • #11
                      I see that spidery little 'black widow" in your third picture above. "For want of a nail a shoe was lost". Think the flimsy "retaining washer" was start of the issue?

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                      • #12
                        Originally posted by PaulCDF View Post
                        "For want of a nail a shoe was lost"
                        I like that quote! I can only guess the problems are all related, sloppy bushing and clutch basket wobble transferred more thrust to the clutch hub nut and the tab washer wasn't up to the task, then throw in a dragging bearing and who knows! I've never had this gearbox apart until now, there's my 47,000 miles before some noises started last year, plus however many miles the gearbox had on it from before...so that's good!

                        Pisten Bulley is Harry Roberts in Vermont.

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                        • #13
                          If you got 47k and all you need is bearings and a bushing you're doing very good.Did you look at the cluster gear shaft?
                          looks like you will be back on the road soon.
                          Tom

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                          • #14
                            Howdy sir,

                            Very few loyal dusty trail horses of the two wheeled variety will deliver beyond their last gasp like an Indian Chief…I never had to walk home or wrench roadside in the dark with flashlight clinched in teeth. Here’s how wobbly they can get in every respect and still provide a delightful riding experience.

                            https://petergz.smugmug.com/Motorcyc...-Chief/My-346/
                            Cheerio,
                            Peter
                            #6510
                            1950 Vincent - A Red Rapide Experience

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                            • #15
                              Good read PRG Thanks!

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