[TR] Triumphs Digest, Vol 16, Issue 39

[DAVID MASSEY]

 Why are they spinning?  It seems to me that they are trapped between the mainshaft and the synchro hub with has splines which engage the splines on the mainshaft.  Is the synchronizer engaging them in some way?  I guess I'm not seeing something looking at the pictures.
I'm afraid I can be of no more help.  I've reached the limit of my experience.  Good luck
 
Dave 


 
 
-----Original Message-----
From: aribert neumann <aribertn at gmail.com>
To: triumphs at autox.team.net
Sent: Mon, Mar 20, 2023 8:45 pm
Subject: Re: [TR] Triumphs Digest, Vol 16, Issue 39


Dave:   Thank you for your thoughtfull reply!   The groove in the main shaft that locates the split collars is not as bad as it looks - most of the taper turns out to be material worn off of the split collars and welded onto the main shaft.  I have cleaned up the groove, to the same dimesion as the groove on the new main shaft I bought (that has the oversize issues) and that took out all the taper.  
 

The concern I still have is how to prevent the split collars from spinning in the future to prevent this from happening again - either on the old shaft or on a new shaft.   The split collars are not bearings or bushings and if they keep spinning in the future I'll see the same problem.

    


From: DAVID MASSEY <dave1massey at cs.com>
To: "aribertn at gmail.com" <aribertn at gmail.com>, "triumphs at autox.team.net" <triumphs at autox.team.net>
Cc: 
Bcc: 
Date: Mon, 20 Mar 2023 12:39:48 +0000 (UTC)
Subject: Re: [TR] Calling anyone with transmission rebuilding experience - second attempt, part 1
 It has been many years (< 25, I think) but I once rebuilt a TR6 transmission with a used mainshaft that had similar wear on a shoulder like that.  There was a thrust washer that fitted up against shoulder.  A few years later I was rebuilding it again.  The thrust washer had broken into parts.  My solution was to buy a new mainshaft (that is a story in itself) along with some other parts.  25 years later that part is still soldering on.  (I had to rebuild again for layshaft issues but that's unrelated)
I would be very reluctant to reuse that mainshaft.  The raised ridge is not what worries me it is the fact that the edge of the grove is not square and the thrust applied by the helical gears will point load the split collars and they will fail again.  The TR6 transmission si probably different but the basic design is similar and the force loading is also similar.  Helical gears are sued to keep tooth noise down but the fact that they are wound in a helical manner around the axis means the forces applied to the gears is at an angle to that axis.  Part of that force is used to rotate the shaft but the other is applied to the bearings at either end of the transmission meaning the split collars in your case will take up that force as an interface between the shaft and the bearing inner race.  I don't have enough experience to say whether the transmission will last a week, month, year or 10 years with that shaft but I would have much more confidence in a new, quality shaft.
 
Dave 


 
 







---------- Forwarded message ----------
From: DAVID MASSEY <dave1massey at cs.com>
To: "aribertn at gmail.com" <aribertn at gmail.com>, "triumphs at autox.team.net" <triumphs at autox.team.net>
Cc: 
Bcc: 
Date: Mon, 20 Mar 2023 13:30:54 +0000 (UTC)
Subject: Re: [TR] Calling anyone with transmission rebuilding experience - 2nd attempt, part2
 That looks like the heat treated, hardened  surface is starting to break up.  That is what happened to my layshaft.  Another reason to abandon that mainshaft.  If you have an alternate bearing combination that doesn't relay on that surface for the bearing rollers then the hardened surface is no longer critical.  But this is above my pay grade.

BTW, I misinterpreted one of your previous photos.  The split washers transfer the lateral forces from the synchro hub to the mainshaft but the end result is the same, with a compromised groove surface like that the split collars will fail prematurely.   If you open the grove to clean up the shoulder will the split washers stay in place?  If they fall out you have serious problems.  Even if they stay in place will it increase backlash?  Can you get oversized split collars?  Make shims?  All this is above my pay grade.
 
Dave 


 
 





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