Do you need to shim the outer ring or the inner ring of the bearing?..John
Hi John, and all.
I'm sorted now I think as I've had an offer to make me one - job sorted.
It is the crankshaft of a 1960 Triumph Bonneville which justifies to the timing side by passing through the bearing into the timing case and then a clamping washer, pinion, pin and nut are fitted to lock it all against the bearing.
When I do that (after having the crank re-built and new bearings) the con rods are not running centre in the bores and it needs a 35 thou shim under the bearing (between the bearing and the crankcase half) to move the whole crankshaft over by 35 thou when locked up and thus centre the con rods in the bores.
The beauty of shimming under the bearing (actually more of a washer/spacer in a way) is that it is not a moving part and simply serves to distance the bearing 35 thou out from the crankase half. Putting a bearing shim on the crankshaft as I had been suggested brings with it the challenge of moving parts.
Interestingly the Triumph books all mentions shimming behind the bearing to get the crankshaft aligned, but having spoken to several long standing Triumph engine builders both unit and pre unit I haven't come across anyone who has bothered to measure or do it yet - they seem to allow the sideways movement on the rods plus the free play of the piston on the gudgeon pin/little end take up the mis-alignment and bolt them together that way.
Seems odd to me (and I'm no engineer) assembling the engine that way with the con rods as much as 35 thou out of central alignment to the bores.
Anyway, that's what I'm planning to do.
Thanks for everyone's interest and suggestions - I think thanks to a member on the South Coast I am sorted now.
Cheers
Stuart