Life's been getting in the way lately, but I finally found a couple of hours to strip down the BSA gearbox
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With the drainplug effectively missing, I pulled off the inspection cover on the back of the box to drain the oil. Of course, nothing came out because there was nothing in there, the oil having managed to seep out of the various escape routes over the years and then taking residence on the outside of the casing, the lower frame rails, the mainstand, swingarm, etc etc.
Unlike the Norton gearbox, which has remained oil-tight since I overhauled it several years ago, the BSA box does not employ any type of seal for the gearchange and kickstart shaft where they exit the front cover, so these are prime favourite leaking areas. This particular box benefits (not!) from having no gaskets on either of the two inspection covers or in-between the front cover and casing. The gaskets should be there of course, but instead there is evidence of copious amounts of hylomar being used instead, the last time it was taken apart, whenever that was. Brilliant.
So a few pics of the stripdown. This is what lies behind the front cover - gear selector, kickstart pawl and spring, speedo gear...
And this is what is revealed with the cover removed...
With the nut removed the cases can be separated. Here you can see the smaller of the two mainshaft bearings, the other being behind the final driven sprocket at the back...
Not sure how this damage has been caused to the back of the intermediate case around that bearing - maybe a lack of care drifting it out previously. The bearing doesn't actually seat on that part where the alloy is split and deformed, and despite the crack it feels pretty strong and not about to break off. I plan on drilling a small hole at either end of the split and leave it be....
First look at the cluster...
Thankfully it all looks good. No significant wear, no pitting, no chipped teeth...
Cleaned up the case - note the ally spacers that have been attached to line the box up with the engine....
And then reassembled with the engine plates to have another proper look at that sump plug issue - now thinking it's probably not an issue at all, I'll just need to buy a new one and it looks accessible, can't think why it was ground off in the first place now
...
And that's it. Need to order a shed-load of parts, both mainshaft bearings are shot, there's numerous phospher bronze bushes that need replacing, gaskets, oil seal, various screws and washers, all coming to a tidy sum and possibly not all available. I'll be making enquiries when that 'life' thing allows me to do it.