For the best info on locking systems, refer to the book:
Nuts, Bolts, Fasteners, and Plumbing by Carroll Smith.
Generally he indicates that there are few effective locking mechanisms.
I'm at work and don't have the book handy, but if memory serves me
correctly nylock nuts are not really considered to do much.
I use nylock nuts on my porsche's valve covers everytime I change the oil
and adjust the valves - there aren't many replacements even though they
aren't the best system. This makes for 34 new nuts and washers every 6000
miles - at least they come in a package that is fairly cheap.
Phil Bates
'58 MGA
'67 MGB
Misc others
> >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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