Saturday, 7 April 2012

DHC’s gearbox rebuild part 2

Picked up a few freshly machined bits and pieces from a friend this afternoon. To start with I decided that, while rebuilding a gearbox for the DHC, it seemed like a good idea to see if I could get the fairly standard oil leak from the selector shaft at the back of the gear box sorted. Ultimately time will tell if it really works, but I think this should do the trick. First I selected an oil seal that would seal around the ø16mm selector shaft. Turned out that a ø16x24x5mm oil seal was perfectly suited for the job, and cheap too!

With the seal sorted, the rear casing was dialled in on a milling machine, and the first part of the hole for the selector shaft was enlarged to accommodate the seal. Also made sure the groove for the original O-ring seal remained intact so I now have a double seal there ...

Also changed the small plug in the oil galley underneath the rear casing for a plug with a proper copper seal. Much easier to check the oil flow this way.

And to finish work on the gearbox for the time being I measured the end float on the bearings for the mainshaft and the layshaft. It always looks quite easy but in the end it took me well over an hour to measure the end float on both shafts. The layshaft turned out to be spot on, but the main shaft needs a substantially thicker shim. So now waiting for that to arrive!

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