Author Topic: Mastif 4 speed transmission  (Read 1397 times)

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Offline Dewey

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Mastif 4 speed transmission
« on: 02 Mar 2014 at 01:55 »
Hi all.

 The Fulton bikes transmission shift rod had obviously been bent and straightened more than once so we've decided to see if there was a way to improve on it, which there was. A full disassembly showed wear in the obvious areas, such as the small gear that drives the sprocket gear, and some deterioration of the sprocket gear bearing surface but other than that it was in decent shape. All but one of the sprocket woodruff keys were intact. The others were either sheared or missing altogether.

For the shift rod repair I got a piece of 304, 1/4" SS rod and put some threads on one end and the other got turned down to .196", and then cut off the old rod from the rack and drilled a hole .196" in diameter 7/16" deep. The SS rod has been silver soldered in place and it all looks quite strong. My question is - how long is this rod normally? Right now it's sticking out about 1" out of the case bushing in 4th gear. That's about twice the distance it was before because I'm fairly sure it was cut off and re-threaded sometime in its past. My other question is in regard to the shift selector drum detent mechanism. The one in it now appears to be made from a new hollow bolt with the spring & detent plunger inside. Spring pressure is rather weak , to the point it barely locates the drum position. I suspect it was changed to lessen the strain on the shift rod to reduce the bending of the rod, but I can see it would be very difficult to know if you're actually in whatever gear you selected when riding the machine. Hopefully, one of you have a pic you could share.