The first is the little '14mm' bush which fits between the low gear and the sleeve gear. The tiny 0.75mm flange on this serves to maintain axial clearance in the gearbox but the little flange only makes line contact with a chamfer in the low gear. This results in rapid wear and a gearbox which develops more and more clearance over time.
The second problem, which is much more expensive to fix, happens at the other end of the sleeve gear where the 12 x 5mm rollers wear at the kickstart shaft and eventually start to run out of line causing more & more damage.
The solution has been to buy a new 14mm bush, kickstart shaft and rollers at, usually, an enormous cost with little assurance that you won't have to do it again after a few years of use.
After a couple of my friends were faced with expensive bills for replacement parts, I decided that a better solution was needed.
My answer involves
a) making a new two-part 14mm bush with a much larger bearing surface for the interface between low gear and sleeve gear.
b) putting a hardened sleeve (better than the original shaft) on the kickstart shaft where the 5mm rollers ran and fitting 35 smaller rollers into the space.
The old low gear bush is pressed out .......
The new bush is inserted and has a thicker flange to make up for the little 0.75 mm flange on the original bush.
A new bush goes in to the sleeve gear , complete with lubrication groove.
Next job is to inspect and clean up any damage at the other end of the shaft.....
The hardened sleeve fits over the damaged area, providing a new bearing surface.
With the sleeve pressed onto the shaft, the new rollers can be added....
Because the sleeve is made long to provide support for the 'repair' the support bush needs to be opened out and a new, shorter, location dowel fitted....
I have already sold seven of the kits ( with an instruction leaflet) that I'm making and provide a fitting or exchange service for those without the necessary tools.
Kits are £80 GBP plus shipping
Installation or exchange is £105 GBP plus return shipping
