If like me you have several bikes both new and old it makes life a lot easier to have all the gear changes on the same side and working the same way . I made the decision many years ago that all future bikes of mine would have left foot up for up changes .
Anyhow back to Sunbeams , starting with the gearbox end plate , the blind bush for the gearchange shaft should be removed . The hole is then reamed out to 18mm and spot faced to 52 mm diameter on the outside . The shaft support shown below is then attached with four 5mm allen screws fom the inside , being careful to align the 18mm bores and not foul the gearchange spring with the screwheads .
The extension piece is pressed and pinned to the left hand end of the change shaft whilst the other end of the shaft is shortened and tapped ¼ BSF for a bolt and large washer to retain the conical oil seal .
This extension piece could be splined to take the original gear lever although this would leave you with a down for-up-change.
I left the end plain and fitted the short lever which connects to the main gearchange lever via a reversing link . This main lever being pivoted on an inward extension of the footrest , the brake lever is similarly pivoted . Exactly how you arrange the brake and gear lever depends on where in the adjustment the footrests lie .
The brake rod needs to be stepped across at the back of the gearbox , this is the purpose of the double link and cross shaft which pivots in the original bearings . Note the strip which bolts across the back of the double link and acts as the backstop for the brake lever .
Finally the toolbox has to be moved back to clear the gearchange linkage , it is as well to use a fibreglass replica as the bottom has to be cut out to clear the brake cross shaft . Aligning it with the battery box looks about right .
