Gearboxes - A couple of pointers

Voyager

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This is just a quick 'heads up' on a couple of things I found in a recent gearbox re-build.

The box was from 'Vincent's' 1991 R65GS - a Monolever bike.

The inside of the box wasn't bad but there was some water in it and some gravel / rust deposits between the output shaft rear bearing and the oil seal.

The output shaft rear bearing was shot whilst the others were mostly OK (output shaft front was a bit worn).

It looks as though water had been getting in down the speedo drive as the drive gear was quite rusty. I cleaned it up on a wire wheel and the rust pitting can be seen here:


DSCN0411.jpg



The rubber boot on the speedometer cable didn't look too bad, but it will need to be properly sealed when it goes back together.

The water has been in there for a while as its the first time I've seen a rust hole in a gearbox shim :D :D


DSCN0413.jpg



I changed both output shaft bearings plus the input shaft rear bearing. Fortunately the roller bearing at the front of the input shaft was good - though I did replace the sleeve it runs on as a precaution.


DSCN0368.jpg



That combination was a lot tighter than the new roller bearing I got from Motorworks :confused:.


Also, Vincent uses the kickstart a lot. The spring looked fine but I thought I'd change it just to be sure.

It just goes to show what happens to a spring that has been under tension for 21 years . . . Old spring on the left :augie


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Its actually relaxed by about 90 degrees :eek:.

So if you think your kickstart is getting a bit floppy - you're probably right :D.


The box had to come out as the Small Pawl Return Spring had broken meaning that the bike was stuck in the last gear selected:


DSCN0245.jpg



The spring costs £1.43 - but the box has to be stripped to replace it.

I replaced all three selector springs while I was in there.


Before opening the box, I turned it upside down and tried to select the gears and with a bit of fiddling it worked :bounce1. So - if you are stuck out in the wilds and the pawl spring breaks it really should be possible to select a suitable 'all round' gear such as third by turning the bike on its back. That should get you home (slowly) :D.

Urban Myth its not :augie.


So, to conclude, If your bike lies out in all weathers make sure that the speedometer cable is properly sealed as water in the box does cause damage :thumb :thumb.

Bob.
 
I can't thank Voyager enough for generously offering to do the job on my gearbox, nothing that I could have done myself. Never met the man, and I realised that he helped me in the past when my bike was vandalised a few years ago and sent me an wiring loom fix it, top man:thumb2. The gear box is back on the bike and has never run as smooth. I have now sealed the rubber boot on the speedo cable with sealant gel to prevent the corosion mentioned above. So glad to have my great little machine back on the road:clap
 
Just changed the rubber boot on my speedo drive today as it had those little cracks on it. No sign of any water inside or rust, used the funnell method of spreading the boot to fit back on and sealing it up to the cable with silicone and cable tie which might be a bit OTT but its a good one now.
 


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