Saving Old Seagulls

It seems to me that the differences between a fixed and a clutch drive 102 gearbox is fundamentally a longer propshaft and a few extra parts (spring, large brass washer, clutch fork etc) but the casting is the same, thus a fixed drive could be converted to a clutched version.

True or false?

The best way to be sure is to check the parts book, 2 different part numbers for the case would imply not identical.

CL 1374 Reduction gear housing (clutch drive) 12 : 30 ratio.

1374 Reduction gear housing (fixed drive) 12 : 30 ratio.

If you compare the 2 part lists & pictures you will see all the parts required.

Good point, I confess I hadn't noticed that detail. However, the only difference the drawing reveals is the profile of the casting at the output end; the clutch drive has an additional bevel and a bush that fits into it. Interestingly, I saved these parts from a scrap item that were made from brass as fitted to early gearboxes.

And the prop shaft bush is in a different location!

Yep, that would have to be re-positioned or replaced, which could prove difficult and /or disastrous! But I saved that part too, and it was removed easily enough, as I recall, although I did not test it for wear.

Anybody got a 102 gearbox they can bear to part with?

Earlier 102 boxes that have a bronze/brass "wedge" where the clutch fork runs up and down should theoretically be readily converted each way. You will of course need all the relevant parts for whichever way your converting.
Later clutched boxes that are all aluminium have the "wedge" cast as part of the gearbox casing . This "wedge" in later boxes can end up wearing quite badly and the operation of the clutch can get a bit hit and miss.
Oil is important too as we've been discussing elsewhere.

But since I have only a few of the requisite parts it's so far a non-starter, Oh well, I'll just have to wait. I only want another clutched box as a spare anyway, to be honest. Thanks for the input though.