Here I have a locking tool to hold the gearbox sprocket so you can undo the sprocket nut when you want to change the sprocket. I've tried it on 18t/19t/20t sprockets, You can torque the nut up properly when you refit the nut.
Gearbox sprocket for BSA C25,B25,B44,B50 Triumph TR25,TR25W , 14T OEM: 57-4306
Gearbox sprocket for BSA C25,B25,B44,B50 Triumph TR25,TR25W, 13T
TRIUMPH 4 SPEED GEARBOX SPROCKET NUT SOCKET
Triumph T140 TR7 5 Speed High gear Gearbox sprocket oil seal (60-3512)
4 Speed High Gear Lock Tab Washer Gearbox Sprocket Triumph T120 T2116
TRIUMPH GEARBOX SPROCKET OIL SEAL 60-3512 1973-83 5 SPEED T120V TR7 T140
