Sturmey Archer Gearbox Cover
Parts for the Sturmey Archer gearbox proved hard to find. Not suprising when you consider it is over 90 years old! The end cover was badly damaged and beyond repair so we bought a casting from Ken McIntosh in New Zealand and set about machining it.
The Original
As you can see in this picture, the original end cover is badly damaged, the top ear had been broken off and badly welded back on and there were a lot of cracks around the kickstart shaft boss. Somebody had obviously tried to use it as a pattern to cast some new ends, hence the filler all over it. The cast ends did come with the project but they were a poor finish and, the final nail in the coffin, this turned out to be the wrong end for a CS1.
Machine the inside
The kickstart shaft boss was held in the lathe and the inside machined, the gasket face was skimmed and the recesses machined to clear the kickstart mechanism and shaft
Clutch worm and fixing hole studs
The casting was then mounted on the milling machine to bore and tap for the clutch mechanism and drill and counterbore the fixing stud holes.
Kickstart shaft and stops
The casting was turned over in the milling machine and the recesses for the kickstart stops where machined.
We were able to salvage the stops themselves out of one of the old covers that came with the bike, but they are available if you need new ones.
Kickstart shaft and stops
The casting was mounted on an adjustable angle plate to drill and tap the filler/level plug hole.
This gearbox is filled with semi-fluid grease but I top it up occasionally with some engine oil.
Finished
We would normally blast clean and wire brush the casting as this blends everything in and gives a nice finish, but as the CS1 it's on is in oily rag condition we decided to leave this as is to blend in with the rest of the bike.
