Promar uses a crankshaft micro-polisher with a rigid polishing system. The QPAC Q190-38-3 has a solid
abrasive tape that wraps around the journal and is backed up with a shoe. This shoe applies equal
pressure all the way around the journal while it is being polished.
Traditional polishing techniques use a manually operated belt sander that can alter the geometry
of the journal, slightly creating some taper or out-of-roundness. If the surface finish on the
crankshaft journal is not right or the geometry is slightly off, the bearings will suffer the consequences
when the crankshaft is put into service. While polishing in one direction and then automatically polishing
in the opposite direction, the QPAC system leaves a better finish and eliminates microscopic peaks that
can cause premature bearing failure. The finishing process always ends in the same direction as the engine
For thrust surfaces, a separate polishing arm is used. Polishing the thrust surface on the crank is
important to minimize the risk of thrust failure on vehicles that have electronic torque converters.
With many of today's engines requiring extremely smooth journal finishes (as low as 6 Ra or less)
because of tighter bearing clearances and the use of thinner viscosity 5W-30 motor oils, there is little
margin for error. In one pass the QPAC takes the finish down to 6 Ra or less and provides a superior finish
to any polishing systems out there today.