[TR] Pilot bush TR3A

[Randall]

> Interesting discussion. I'm currently rebuilding my TR4A engine and have 3
> pilot bearings. One is new and they all fit loosely in the crank. My
> question is should it be loose in the crank, some I've asked say OK and
> others say no and to locktight it into the crank and or knurl it so that
> it fits tight. I'd appreciate opinions and reasons for your thoughts.

My opinion is that it doesn't matter, as long as it's not so tight that it
binds on the shaft when it gets hot (the bronze bushing probably expands
with heat faster than the steel hole it's in).

Mine have all been loose fits at room temperature; both the ones I've taken
out and the ones I've put in.  I've never seen any sign of a problem with
them in over 300,000 miles driven (granted not all on the same engine or
even the same car).

The hole in the crankshaft is polished and on-center; so I can't see any
reason it would matter if the bush turns with the crankshaft or turns with
the gearbox shaft (or turns at some speed in between the two).

Remember, it only moves at all while you're holding the clutch down, so it
doesn't see a lot of motion.

-- Randall