I've only just found this old topic; what a shame the photos are no longer available.Ginetta lad wrote: ↑Thu Aug 04, 2016 12:29 pmOk I've got the box cover off and the shaft out. I like your double side support idea but need to work out an accurate way of centre pointing the blank cover through the existing hole for drilling. It's 14mm diameter on the bearing surfaces but not all the way along the shaft. The bush and oil seal on mine need a 20mm hole but the standard oil seal is poor and only 3mm thick. Have you found a better one? If the one side only approach is taken then only the new hole is used I guess it doesn't need to match the opposite bush and hole. Now I need to find someone with a lathe to turn down the gear shaft. I wonder if the opposite side of the shaft is centre drilled and threaded then the remaining rhs part could be turned down and screwed into it and be lock tighten or soldered as an alternative to welding? H
I've converted a 5 speed in this way, using my own method. I thought I'd add the following as it might be useful to anyone who wants to convert a 5 speed box to right side gear-change.
To mark my "blank" outer cover with an accurate centre for machining I first removed the gear-change shaft. I then made up a 14mm diameter centre punch from a metal part I had in my toolbox, wrapped with a couple of layers of electrical insulation tape to be a snug fit inside the existing bush in the inner casing. I then refitted the outer cover and then placed my centre punch through the rear of the bush in the inner casing, as if it were the original gear change shaft.
A swift tap on the centre punch (from the centre line of the 'box) accurately marks the required centre of the blank spigot inside of the outer cover. The outer case will bolt flat on a milling table on its outside face so the centre punch mark is on the top face.
I retained the existing bush in the inner casing (I wanted double sided support for the shortened gear-change shaft) with a neoprene coated sealing plug behind it and fitted a plain, sintered bronze bush (20 x 14 x 12mm) in the outer case and an oil seal (20 x 14 x 3mm) on it's outer edge to seal the gear change shaft.
Total cost to convert my box on a DIY basis was about £25 (£15 for a new bush, oil seal and blanking plug and another £10 to have the outer cover machined locally).
I converted the gear change shaft myself, for double ended support and tbh, it wasn't so easy. Because portions of it are machined down to a smaller diameter than 14mm, I had to cut off and drill out the inner operating arm off the gearbox end of the shaft and then braze it back on in the correct position on the length of the splined part. In retrospect I'd have MIG welded it because it would have been tidier, quicker and easier and required less fettling afterwards to clean it up.
Or, as already stated, you can buy parts for a single sided gearchange setup as shown in our host's Bullet catalogue and re-use the existing bush in the outer case. It might even be possible to re-use the old oil seal - but they're very cheap to buy anyway.