Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board 1970 T120 high gear bush

On stripping the gearbox and inspecting the high gear bush I have noticed that about half way down inside the bush there is an area about 1/2" wide or so of wear and galling which is quite rough to touch. The strange thing is that the high gear is a good fit on the shaft with a very small amount of play which I percieve to be within tolerance because both ends of the bush are in good condition. The shaft only shows a small amount of wear in the corresponding area although it does have a pollished look. Is it necessary to replace this bush? and what would have caused the wear in the centre? If the bush is replaced, is there any advantage heating the component on disassembly?
I would appreciate any advice from someone who has carried out this work.
Many thanks,
Mike

Are you sure the roughness is in the bush? There is a gap between the two bushes. I think the original bushes had an X groove in them to carry the oil across the bush, could that be what you are seeing?
It could be a particle was caught between the bush and shaft, then the bush was doing its job and taking the wear.
No need to head the gear to replace the bushes, the steel expands slower than the bronze.
Very difficult to replace only one bush unless you split it. Easier to replace both. Note the distance the end bush sticks out from the end. A tube with a stepped I.D. can be used as a press stop.

Sorry for the delay in responding. There is only one bush and I have managed to extract it with a suitably machined drift. I have decided to replace it as the bore looks quite damaged in the middle. Maybe it was a partial seizure or attacked by unsuitable oil or contamination. It is strange as a friend with a T110 had the same wear/damage on his high gear bush.

Aren’t the one piece bushes sometimes relieved in the center?

Chris

Yes!