Re: DIY Gearbox Rebuild Questions

[bearbvd@domain.elided (Greg Hermann)]

>1)  As I understand it, to replace a gear bushing, you have to press out the
>old one, press in the new one and then hone the new one to fit.  Should I
>take this to a machine shop or can I do it (or any part of it) myself?

Probably best left to a shop.
>
>If I take it to a shop, what is the correct bearing clearance?

About .003" . SURPRISINGLY loose !! If too tight, they tend to seize.
(Don't ask how I know!!)
BUT--make sure the shop KNOWS !!!  :-)
>
>If I try DIY, then how?  (Maybe if you have to ask, the answer is don't
>try...)  I can probably figure out some way to press it out/in, if I can
>find the right size punch or substitute.

Getting the old one out is pretty easy if you have a good touch with a
caping chisel.

A custom fit drift with a shoulder on it is the only (appropriate) way to
install a new one.

 But I've never honed a bearing.
>Can I use something like a brake cylinder hone and hone it until it fits?

NO!!

>3)  All of the bushings on the main shaft are clearly toast, the mainshaft
>had brass colored bearing material smeared all over it, but it cleaned up
>nicely with a gentle scrubbing with a 3M pad.

Shaft whould be OK as no evidence of overheating (such as strw to blue
coloration).

Surprisingly, the ball
>bearings on the input shaft look fine.  The roller bearings inside of the
>fifth gear don't look so good though.  There is quite a bit of play in them,
>I can *rock* the gear back and forth on the shaft.  Do I replace just the
>roller bearing cage or do I replace the sleave that slides over the shaft
>which functions as the inner race for the bearing?

Both.
>
>Thanks in advance for any help.  If I can successfully pull off a gearbox
>rebuild, I will feel like a true Alfista!
>
HTH !

Greg

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