Harley-Davidson Main Bearing Lapping

With the exception of the Twin Cam and the '77-'85 Ironhead Sportsters, all Harley Big Twin and Sportster pinion shaft main bearing outer races need accurate sizing and aligning by a lapping process. Flatheads, Knuckleheads and pre '56 Panheads also have this requirement on the sprocket shaft main bearings.

Shovelhead main bearing lapping

Lapping a Shovelhead pinion bearing race.

We use the recommended service tools and calibrated, measuring equipment to ensure that this procedure can be carried out to a tolerance of one ten thousandth of an inch (.0001").

Please note that even the use of a new crankshaft in a new set of crankcases requires that these components be measured and the correct bearing size chosen to enable the appropriate running clearance to be achieved.

We have also designed and manufactured a number of press tools so that we can replace these bearing races, when necessary, without causing damage to the crankcases.

This process, and the use of the highest quality bearing parts (which we stock and supply), is a fundamental part of Harley engine building, irrespective of the performance level.


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