Triple gearbox rebuild.

Made and installed the sleeve gear bushes. I didn't use a reamer in the end. I just set it up in the 4-jaw chuck and line bored the bushes a bee's dick at a time until the shaft would just go through, then did the oil scroll and followed up with a bit of fine emery paper wrapped around a 16mm bar. It all worked quite well. Radial clearance finished up around 0.04mm as near as I can measure it (digital caliper).

I'll start reassembling the gearbox tomorrow. Shouldn't take long to get the crankcase halves back together. It's been a while since I took it apart. I hope I don't leave out any important parts like selector forks.  :D

Cam
 
I too am experiencing Garage and Tool Envy - NICE Keith.

I believe most of us here know how to dissemble, clean and reassemble a Breganze Gear Box. My 1st question is: What does it take to replace all the bushings - Missed and grinding shifts?

Fortunately with my first years as a Hell Rider Insanely slap shifting without the clutch I don't believe I hurt it as bushing are tight with no chipped gears and still shifts as good as the day I bought the bike when new.

About the only issue I have, since day one, is that I must deliberately remind myself when up shifting from 4th in 5th is to avoid a False Neutral which I understand is characteristic of the Breganze Gear Box. My 2nd question is: Is there a fix for this?
 
breganzane said:
Cam,
Don't forget the pin that retains the selector fork shaft.
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Thanks Steve. I pulled an old galvanised nail out of my car tyre the other day (probably picked it up from your driveway). I'll use that. It's a bit bent, but I'll straighten it first. No cowboy bodges here ...
 
Gotta love good pics to go with a good yarn - very nice work and very nice pics, Keith.

Probably my ignorance at work here, but if using a fixed 17mm reamer, how do you guarantee a perfect fit to the cleaned-up shaft stub? Means the shaft has to be exactly matched to the finished cut, doesn't it?

Wouldn't an adjustable reamer be better suited? I'm passable at standard machining, but have very little experience with reaming for a perfect fit. I'd most likely take the 'easier' option that Cam the DellortoUomo did and use the boring bar.

QF
 
Piranha Brother 2 said:
Gotta love good pics to go with a good yarn - very nice work and very nice pics, Keith.

Probably my ignorance at work here, but if using a fixed 17mm reamer, how do you guarantee a perfect fit to the cleaned-up shaft stub? Means the shaft has to be exactly matched to the finished cut, doesn't it?

Wouldn't an adjustable reamer be better suited? I'm passable at standard machining, but have very little experience with reaming for a perfect fit. I'd most likely take the 'easier' option that Cam the DellortoUomo did and use the boring bar.

QF
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That is where the experience comes in  ;) Worked fine in this case as there was no wear on the mainshaft so the hole is reamed dead size and I then finish by honeing the running clearance to suit the shaft dimension, if the mainshaft shows wear any ridges must first be stoned off before measuring and manufacturing the bushes to suit and an adjustment in size to accommodate the wear must be calculated, would bore these and again finish with the hone. Adjustable reamers like adjustable everything else's are generally a waste of time, almost impossible to get an acceptable finish due to the straight cutting edges.

  Keith
 
Adjustable reamers like adjustable everything else's are generally a waste of time, almost impossible to get an acceptable finish due to the straight cutting edges.
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have found that to be true - but have used them carefully with emery paper round them to "hone" the odd gnat's cock off a few awkward things before. - Regards - Phil
 
I'm renovating a main and layshaft and I have bought a nice set of new bearings.

With all this here technical talk the bushes have spontaneously become as loose as fcuk , and that means I now am duty bound to strip the lot and measure the shafts and the bushes for wear.

Sometimes, ignorance is pure bliss. :'(

joe
 
jotajoe said:
Sometimes, ignorance is pure bliss. :'(

joe
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Hey Joe ... where ya hoin' with that bush in y hand?  ;)

Ah, never a spoken word was truer (or vicey versey!). If you hadn't read the engineer's almanac of this post you could probably have run your beast for years trouble-free! Take heart that I have broken a mainshaft stub on my v high mileage SF1, and that can only have been due to clearance becoming excessive over time. Do it and make it right.

What's the pro & con word on the SFC and later triple needle roller setup? I converted my clutch drum to needle roller, but not sure it was necessary (old bush was original and had play, so something needed to be done).
qf
 
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