Bearings, bushes and pinions
Rolling element bearings
Removal
Usually, such bearings are secured by interference fit into housings cast and machined into crankcases, gearbox shells, end plates or other components. And – usually – these components are manufactured using aluminium or aluminium alloy which fortunately for us expands at about four times the rate of steel/ steel alloys, making the removal of ball bearing races, the outer rings of crowded roller, caged needle roller etc bearings easy in 98% of cases.
Rather than press out the bearing, even if this is possible, I prefer to heat the case to 250°C in our old domestic oven (part of the equipment in a large shed, housing presses, an old lathe for grinding only work and many more ‘precious items’). Then, wearing a stout heat resistant leather glove, I strike the component open side downwards on a wooden board or bench. With luck, the bearings and bearing rings drop out. In a worst case scenario they don’t, so I try the heat treatment once more and if this fails again, next (and while supporting the casing appropriately around the bearing housing) they are pressed out – again, it helps to preheat the cases to minimise press pressure.
Even worse is this situation with blind bearing housings and, for me, a final, last ditch method is to drill two opposite or three diametrically equal 3mm holes through the housing from the back to mate precisely with the bearing’s outer ring. Then, using two or three – as appropriate – thin (2.75mm) equal length high tensile rods* press out the bearing, or if no press is available, tap out evenly with a pin punch.
On completion, the holes can be either aluminium weld repaired or plugged with aluminium rod. Neither approach is great and welding has risks, but if the bearing is stuck fast, extreme measures are necessary.
* Often, I make a rod guide from appropriate large diameter plastic bar. It takes only a few minutes to machine a 15mm thick slice from the bar, and drill
