X-Mozilla-Keys:                                                                                 
Ed Anderson wrote:

Thought I would relate my experience with the Ross PSRU.  Vance is correct
that at low prop rpms the prop apparently loads and unloads between engine
power pulses and this indeed causes the engine end of the drive shaft to
pound on the end of the eccentric shaft or more likely the flywheel nut.  I
recently overhauled my 13B mazda engine for a unrelated reason and found
evidence of the marks by the spline teeth on the PSRU side of the flywheel
nut.

  One indication that you will get of this occuring is an irregular metalic
clanking sound at low engine rpm.  Most of us have found that if the idle
rpm is raised to keep the prop loaded between power pulses this eliminates
the problem.  In my case I need to keep the engine around 1500 rpm (prop
approx 750 rpm with 2.17:1 gear ratio), others have found the same procedure
works.

Clearly, a thrust bearing would be a better solution.

 
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