A lock washer needs to be crushed flat to work properly PF,
however, upsetting the threads might also work but not as
positive as commercial locking nut. The nuts on the outer bolts
are not meant to be torqued down, if they were they would crush
the support closing up the required 1/16" clearance between the
upper plate and lower retainer.
In the absence of the correct castle nuts which are locked with
a cotter pin after snugging them up, a nylock or better yet, a
commercial distorted thread high temp nut can be used to make
the adjustment.
There has always been some cornfusion as to what the engineers
had in mind. It's really quite simple though. You want the
support held snug between the plate and retainer but you want
the clearance so when the engine torques over it will absorb
the movement by compressing the rubber slightly. When that
occurs the tension is off the outer bolt and that's the reason
for the locked nut.
Denny Graham
Sandwich, IL
