Gearbox Post Mortem

Stirlingmoz

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I can’t progress the green laner project until the carb bodies come back from vapour blasting and saw this gearbox on eBay.

I thought it was worth a punt at £40 for the parts alone.

Sellers description

IMG_5214.jpeg
 
Got it open and on first inspection, the rear bearing on the output shaft has collapsed.

Not sure how the outer bearing is still with the inner ! Everything inside has a silvery sheen and the magnetic drain plug is a Christmas tree of shavings..

IMG_5239.jpeg

It’s going to need new bearings all round at the very least but I’m hopeful it’s saveable.

More strippage, cleaning and assessment of what’s left to follow..
 
Stirlingmoz said:
Got it open and on first inspection, the rear bearing on the output shaft has collapsed.

Not sure how the outer bearing is still with the inner ! Everything inside has a silvery sheen and the magnetic drain plug is a Christmas tree of shavings..

View attachment 543054

It’s going to need new bearings all round at the very least but I’m hopeful it’s saveable.

More strippage, cleaning and assessment of what’s left to follow..
Click to expand...
LUCKY BUGGER LOL

#WinnerWinnerChickenDinner
 
Been giving this gearbox repair some more thought.

I find the clutch pull on this /5 engine (heavy flywheel) with /6 gearbox quite heavy these days, especially on longer rides or trips into London.

IMG_5242.jpeg

Thinking I could convert it to run a post 81 flywheel & clutch, resulting in a lighter pull at the lever.

As this gearbox case has minor damage anyway, I could refurb the internals and drop them into a pre 81 /6 smooth case to better match the early engine.

Means tracking down more parts but I’m in no rush.
 
Finished stripping the gearbox this morning

IMG_5244.jpeg

The bearings on the output shaft are really bad and I think the filings have got into the other bearings and gear clusters.

It’s going to have to fully come apart for cleaning and bearing replacement.

This is some of the metallic sludge sitting behind the bearings..

IMG_5245.jpeg

Output shaft doesn’t have a circlip (or groove) to retain the front bearing

IMG_5246.jpeg

And lastly this morning, I cleaned the rear cover with a wire brush and some WD40.

IMG_5247.jpeg
 
Stirlingmoz said:
Been giving this gearbox repair some more thought.

I find the clutch pull on this /5 engine (heavy flywheel) with /6 gearbox quite heavy these days, especially on longer rides or trips into London.

View attachment 543122

Thinking I could convert it to run a post 81 flywheel & clutch, resulting in a lighter pull at the lever.

As this gearbox case has minor damage anyway, I could refurb the internals and drop them into a pre 81 /6 smooth case to better match the early engine.

Means tracking down more parts but I’m in no rush.
Click to expand...
Take your time Pete, just tell me when to collect her once you have finished with “my” bike! ….:)
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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