At 07:55 PM 11/16/03 -0500, Dinnis (BarrMark262@aol.com) wrote:
>Just curious list, as to why do our cars have some nylock nuts as
>fasteners in some areas, and nuts and split washers in others.
I think locknuts can be easily classified as either free spinning or
friction type. Plain nut and split washer would be free spinning, where
you can spin it down most of the way with your fingers and do the last turn
with a wrench. Nylock nuts are friction type, and have to be wrenched all
the way down the thread during installation.
As far as I know, on all MGs through 1980 production there were only two
basic types of locknut used (other than plain nut and lock washer), and
both were all steel construction. The most common one was the castellated
nut used with a cross drilled bolt and requiring a split pin to secure
it. These are commonly used in the front suspension and wheel bearing
spindles, free spinning type. As long as there is no unusual damage to the
nut, these can be re-used indefinitely.
The second type had a split top end on the nut with the thread in that area
slightly compressed to provide an interference fit and lots of friction on
the thread. Two slightly different versions of this as I recall. One had
very narrow vertical slits with about 6 tabs that were deformed
inward. These may have been used on rear spring shackles of some
cars. Another had a very narrow horizontal slit just below the top of the
nut which went part way around the nut, and the metal above the slit was
deformed slightly inward or axially out of pitch. This last one was
standard issue on propshaft and engine mount bolts in the MGA. Both of
these are friction type locknuts, not free spinning. As long as there is
no unusual damage to the nut, these also might be re-used many times, at
least until the short length of friction thread would wear out to the point
of no longer providing friction.
>I prefer the nylock when your fingers and hands are really cramped and
>contorted trying to get a silly fastener attached.
I don't like Nylock nuts much. Aside from being difficult to wrench, not
free spining, they are also supposed to be single use fasteners, throw away
any time they are removed, because the locking device wears out with the
first use. In past years it seemed to be of some importance that threaded
fasteners were intended to be re-useable. If you had to do a roadside
repair in the middle of nowhere you didn't want to have to go looking for
new fasteners. I think the Nylock nuts are popular replacements for
castellated nuts these days mostly because they are cheaper to manufacture,
and quicker to install without fiddling with the split pin. But if you
have to replace it more than once the cost savings is gone.
For critical applications like a propshaft I still use a friction locknut,
either all metal or nylock type.
For the engine mounts I have adopted use of another free spinning type
locknut. This one has an external tooth star washer captured permanently
on the bottom of the nut. Spin down freely with fingers, and wrench the
last turn. They are re-useable a few times at least, but how many times
you re-use is a matter of judgement. When the star washer is totally
smashed and has lost the sharp edges it's time for replacement. They do
seem to last a lot longer than standard split lockwashers (which you night
toss after a single use because they're cheap). I really like the free
spinning locknuts where the space is tight and you need to work with them
periodically. Next best thing to Velcro engine mounts.
Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com
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