The small end bush is made of phosphor bronze and there is very little
maintenance that can be undertaken. If it is worn, it must be pressed out
of the con-rod and a new bearing pressed into place, where it can be
reamed to the correct size.
The old small end bush needs to be pressed out of the connecting-rod
and to do this a tool should be made from steel bar which is smaller in
diameter than the bush and has a spigot turned at one end to fit inside
the bush. You will also need a piece of tube with a hole lager than the
bush to push the old bush into while supplying support to the
connecting-rod. Place the assembly into a vice and press the bush
I like the design of the BSA tool as it provides a smooth
pressure from the thread and nut, rather than the impact of a hammer.
Next line up the oil hole of the new bush and the hole in the con-rod.
Now carefully press the bush into place with the tool as shown in the
diagram, until it is flush with the rod.
You will now have to ream the bush to match the gudgeon
pin. Care must be taken to ensure that the reamer is square to the
con-rod. Clean any residue from the bush before assembling with the
Remember to liberally oil the bush on assembly.
The blades of an adjustable reamer are separate from the
body and are fitted into grooves in the threaded shank of the tool.
Adjusting nuts located below and above the blades control the diameter of
the reamer. The reamers come with straight or spiral flutes, with or
without a floating pilot on solid mandrels, and in several sizes. They are
used to enlarge drilled holes to an exact true size using a series of
small cuts rather than one large cut.