So i’m not paying £30-40 for a new top cap, especially when the bush is replaceable.
First step is to remove the knackered bush (after removing the seal etc) – this is a bit tricky due to being a blind fitting.
The internal flange that the bush presses against doesn’t appear to be structural, so I decided to drill 2No. 3mm holes in it to allow it to be drifted out. There is probably a better way, but I couldn’t be bothered to think of one.
So with the knackered bush out, the new polymer bush can be installed (more on the actual bushes later) – new bush on the right.
With a relief cut in the polymer bush (not sure if that’s the correct term), it pushes in fairly easily with a bit of grease, and using the sleeve as a screw/press. It doesn’t appear that a very tight interference fit is critical in this application as the bush is held in place when the top cap is tightened down.
As above for the lower bush.
Bush info:
Top Bush: 28mm OD, 25 ID, 6mm width. IGUS
Bottom Bush: 25mm OD, 22 ID, 6mm width. IGUS
IGUS have about a million materials available all with different lead times, prices, sizes and uses. Not sure it makes much difference in this particular application.
The 6mm width is the killer on these, I had to buy longer pieces and cut them down to size with a bandsaw.
This also means I have some spare stock bush which I can cut down if anyone else needs one.