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General Minitrail Talk
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'72 CT70 winter restore project
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<blockquote data-quote="69ST" data-source="post: 184800" data-attributes="member: 5"><p>As a mental backstop... as long as the transmission isn't rusty most of the lower end should be usable. Worn shift forks are common, with everything. Worn gears, otoh, are rare. If the primary drive gears & shift linkage are rust-free, you've got a viable lower end that only needs a few parts to bring back to as-new mechanical condition. This is my basic approach, beginning from the worst-case scenario. It can be a bit optimistic but usually isn't. These engines are remarkably rebuildable, no matter what the issue(s). The ones that turn out to be true paperweights are the rare exceptions.</p><p></p><p>Breaker point cams can be polished, successfully. The removable 4-speeds are far easier to work with. But, 3-speeds can be done...slowly, by hand. I'm reluctant to media-blast a flywheel and wouldn't recommend this to anyone who is inexperienced. Chemical immersion isn't a great idea, either; there's no way to be sure that no residue is left between the hub & the aluminum body. For the novice DIYer, Scotchbrite pads + mineral spirits are much safer. You can use coarse to clean the magnets...and to begin cleaning the point cam, if it's significantly rusted. If you just have a heavy "haze" of surface rust, better to start with a fine Scotchbrite and penetrating oil/PB Blaster, or similar. That'll help remove rust and leave a finer finish. If you get a uniformly clean, shiny, surface, you're home free. If deep pits remain, it might be better to source another flywheel. That's not likely...and...3-speed/6v flywheels are not in high demand, IOW easy to find & cheap, if you need one.</p><p></p><p>I'd recommend splitting the cases. There's a lot of scrubbing to be done, inside. I can almost guarantee that the shift forks have the old, dreaded, "smiley faces" and need to be replaced. You also want to be sure that the crankshaft assembly is within wear limits, i.e. no more than 0.018" side clearance, no detectable radial play...and the wrist pin fits snugly in the small end. New tranny bearings are cheap insurace, too.</p><p></p><p>As for the stator, the business ends of the coil armatures can be sanded clean. There are also stator rebuild kits available...new coils/points/condenser.</p></blockquote><p></p>
[QUOTE="69ST, post: 184800, member: 5"] As a mental backstop... as long as the transmission isn't rusty most of the lower end should be usable. Worn shift forks are common, with everything. Worn gears, otoh, are rare. If the primary drive gears & shift linkage are rust-free, you've got a viable lower end that only needs a few parts to bring back to as-new mechanical condition. This is my basic approach, beginning from the worst-case scenario. It can be a bit optimistic but usually isn't. These engines are remarkably rebuildable, no matter what the issue(s). The ones that turn out to be true paperweights are the rare exceptions. Breaker point cams can be polished, successfully. The removable 4-speeds are far easier to work with. But, 3-speeds can be done...slowly, by hand. I'm reluctant to media-blast a flywheel and wouldn't recommend this to anyone who is inexperienced. Chemical immersion isn't a great idea, either; there's no way to be sure that no residue is left between the hub & the aluminum body. For the novice DIYer, Scotchbrite pads + mineral spirits are much safer. You can use coarse to clean the magnets...and to begin cleaning the point cam, if it's significantly rusted. If you just have a heavy "haze" of surface rust, better to start with a fine Scotchbrite and penetrating oil/PB Blaster, or similar. That'll help remove rust and leave a finer finish. If you get a uniformly clean, shiny, surface, you're home free. If deep pits remain, it might be better to source another flywheel. That's not likely...and...3-speed/6v flywheels are not in high demand, IOW easy to find & cheap, if you need one. I'd recommend splitting the cases. There's a lot of scrubbing to be done, inside. I can almost guarantee that the shift forks have the old, dreaded, "smiley faces" and need to be replaced. You also want to be sure that the crankshaft assembly is within wear limits, i.e. no more than 0.018" side clearance, no detectable radial play...and the wrist pin fits snugly in the small end. New tranny bearings are cheap insurace, too. As for the stator, the business ends of the coil armatures can be sanded clean. There are also stator rebuild kits available...new coils/points/condenser. [/QUOTE]
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