> Questions: Is the crank something that's
> automatically replaced when doing a rebuild
Very rarely, especially on the first rebuild.
> or is the original one reworked?
It may even be usable as-is.
> What factors would determine this?
Both main and rod bearing journals should be measured with a micrometer, at
several points for each journal, and the results compared to the service manual.
Also inspect for excess scoring. If it's scored or worn undersize, it will have
to be ground down to the next standard undersize (and corresponding bearings
fitted). Wouldn't hurt to have it magnafluxed for cracks, too. A crack would
be the most common reason for having to scrap a crank from an otherwise running
motor, but I've not heard that TR6 cranks are particularly subject to cracking.
If the thrust washers have failed (which apparently is a relatively common
problem on TR6 motors), the thrust area of the crank will likely need to be
welded up and ground back down.
Randall
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