Dr Joe's Motobecane D52 Gearbox

Published on 21 September 2023 at 15:45

I wish I had more photos but sadly the lights weren't working and I really wanted to get on, Sorry about that, can't be helped. Anyway, the springs came - these were for the shift detent, which consists of a grooved shaft, 4 4mm ball bearings and 4 4mm diameter springs. The whole lot is retained by one of the bearings, it is an absolute nightmare to put it all together without springs pinging off around the workshop, which is exactly what happened last time I tried.

This time was much more successful with the box going back together nicely without any dramas. I have had it apart so many times now I could do it with my eyes shut - it's a real pain the first 30 times.

i have tested first, neutral and second, if they work the rest will work too, it all feels pretty good albeit very slightly tight, I think it will settle in ok with a bit of use, a few heat cycles and some oil in there, it's dry at the moment. I have installed it on the bike, it's in neutral for now, I need to install the clutch next.

The kick start was a bit of a mare to fit but soon played  ball and now does what it should, it engages reliably and returns nicely. It's all very cleverly engineered, they got a 5 speed box in a very small space. The bike came with one small sprocket for the gearbox and four various sized rear wheel sprockets, I will go with the biggest one to start with. According to Rex Avery that rode it on it's record breaking run in Italy it would easily wheelie in both first and second gear so I assume it was geared pretty low.

I need to order some long bolts to hold it all together, the ones that came with it were just temporary. I thought this was going to take much, much more but I am delighted with progress so far. I think I will redo the paint work at some point - it's too light in colour and upon re-reading Ted Snook's account of the development the bike was metallic blue, not flat blue. I should have realised but I never really saw the bike in the sun. I have other excuses, which I will roll out as and when required.

I think, if all goes well, I will be riding this next week. It won't be finished but it will be working. I haven't ridden anything this small for ages, apart from a quick test ride on a Honda MX50 that I fixed up for my mate Malcolm. I suspect it's not as quick as my GPZ1100 chopper. I think it will be fun and it will definitely feel good riding a piece of history that I will have played some small part in.


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