Crankshaft Main Bushes - BSA Pre Unit, Unit and Triumph Twins
Although the needle roller conversion and oil end feed conversion is an advantage and superior to the standard main bush. If you wish to retain the main bush it is esential that the main bush is fitted and machined to its correct tolerances. Firstly the sludge trap is cleaned out and then the crankshaft main journal re ground. The crank is then cleaned once more prior to reassembling the sludge trap. The crankcase bush housing is checked for correct tolerance and ovality. A main bush with an undersize internal diameter is fitted to the casing. The bush is bored perfectly in line and to an exact tolerance to suit the crankshaft journal. The bush is then flashed honed to give a correct oil retaining surface.
The crankshaft can then be shimmed to its correct end float in the crankcases, it is now ready for assembly. If the timing side bearing housing is oversized or damaged it needs to be jig bored to an (over) size and an appropriate bush fitted (A7, A10) only.
High Quality SRM bushes are also sold separately.
| Service Code | Service Name | Cost (ex. VAT) |
| SRMRG2 | Crank Regrind main journal | £30.27 |
| SRMCS6 | Sludge Trap cleaned re assembled | £34.41 |
| SRMCC13 | Fit main bush and jig bore to size | £46.31 |
| SRMCC17 | Jig bore housing (bush housing A7/A10) | £46.31 |
| SRMCS9 | Shim Crank to cases | £41.28 |
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