pat Posted June 8, 2014 Report Share Posted June 8, 2014 (edited) Dear all, Im just interested if any of you know how people maintained their small ends in the period pre roller cage bearings and for that matter, today at 4-t, eg ultra thin BMW. Press in the new bush in place, Ive done, fine drill by adjustable reaming tool 0.01-3mm, Ive done. Maybe Ive done it wrong.... Think Ive read when order new small end bush for eg Pre-65 2-t, "you need to fine drill inner diameter by reaming tool once bush fitted to the con rod" .... Regarding a thin mtr bush 1.5mm eg like BMW, a very skilled man, 55y of expericence, claim that nothing but dismantling con rod from crank will do, -to be able to fine drill a small end bush in cod rod in a "mill"... Eg is this the way how to maintain a 4-t eg BMW by the manual, dismantle the complete crank each time??? Cheers, Edited June 8, 2014 by pat Quote Link to comment Share on other sites More sharing options...
dadof2 Posted June 8, 2014 Report Share Posted June 8, 2014 On a number of British bikes from the 1940s to 1960 where reaming of bronze little end bushes was required the following technique was used. Pieces of aluminium plate were inserted between the conrod and flywheels to prevent the rod moving from side to side. Crank could still rotate and little end could still move back and forth. A jig was then clamped to the crankcases using the cylinder base studs. This jig was fitted with bushes that were a precision running fit on the ends of an adjustable reamer. The jig ensured the reamed little end was exactly parallel to the crankpin / big end bearing. http://www.yelp.co.uk/biz/joy-engineering-motorcycle-camshaft-specialist-bishops-stortford You could try the above link. I have never used them but I know they do precision bushing. The two places I know who used to do this work have now closed. (old engineers retired) Quote Link to comment Share on other sites More sharing options...
pat Posted June 9, 2014 Author Report Share Posted June 9, 2014 (edited) Thanks alot dadof2, Aha of course. The jig a third option not dismantle the crank ..my bad luck in thought.. Jig should not be impossible to machine from ally or steel. Do you know why K type roller cage is useless for small end, does it crack maybe? Was happy for an hour when finally found, after looong time search, odd size roller cage....K. Well, in the back of my head remember something about small end roller cage needs to be specific cage design.. cheers, Edited June 9, 2014 by pat Quote Link to comment Share on other sites More sharing options...
dadof2 Posted June 9, 2014 Report Share Posted June 9, 2014 The jigs were made from heavy angle iron. They had holes drilled in one flange to suit cylinder base studs. The other flange was bored to suit a stepped bush that was held in with 3 socket cap screws. The flange boring and drilling was done with a pair of angles fastened back to back. One angle was then used on the RHS studs the other on the LHS studs. Quote Link to comment Share on other sites More sharing options...
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