List---Today seemed like a good time to post something I ran across a
few weeks ago. The topic has come up a time or two, but what I found
never included the following details, so here we go:
Bentley and other repair manuals (I assume) write that the front hub
bearing end-float be set to .003-.005. Slacken the slotted nut, it tells
you, to obtain this clearance. Fine, but how is this measured? Torqueing
up this slotted nut to a value of 5 lbf feet can leave these wheel
bearings far too loose, esp. if a new, felt grease seal was installed
along with new bearings and races.
I always thought I set my own bearings much tighter than what is
recommended, so I tried to follow the script more carefully this time.
We know that the spindle and nut are 1/2"X20 threads per inch. This TPI
would mean that turning the nut one full turn would be the equivalent of
.050. One 'flat' on the nut would be close to .008.
If all of the end play were to be taken up by tightening this nut, using
the recommended 5 lb. of torque, then backing off "one flat" as further
recommended by the manual, could leave a running clearance of .008. Too
much, and could permit wheel shake. That's when I rediscovered that
there's another hole in the spindle in which to insert the cotter pin.
Duh! This second hole happens to allow a new location half way between
the slots in the nut. Now, the pin can be inserted with only.004 running
clearance.
Many of you already knew this, I'm sure, but since this "other" hole is
always covered up with grease, one needs to know it's there.
I still like to squeeze all of the air out of the gaps in the hub,
before inserting the cotter pin. I do this by overtorquing the nut to
where the hub won't turn by hand. Then back off on the nut and come at
it again using the lighter torque. The hub should turn by hand. Now back
off the nut and find the first "better" hole in which to insert the pin.
You should end up with a running clearance between .003 and .005, as
recomended....and no wheel shake.
Dick
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