Threadedness

[Scott Fisher <sefisher@domain.elided>]

Will Owen gets it right when he says:

"The one piece of wreckage here that I will cling to is
my suggestion that "offside" and "nearside" caps on
the same car are not a case of Trevor being as
lackadaisical as Luigi, but simply a matter of
differently-handed threads on opposite sides of the
car. Anybody out there wanna kill me on that one?"

Not I.  As many people did, I started out in sports cars with the
well-loved, "cheap and cheerful" M.G.  One of the things that appeals to
many British sports-car owners is the idea of wire wheels, those lovely
anachronisms that look so stunning when they're clean, recently painted,
and in perfect true.

So my third M.G. was British Racing Green (actually called New Racing
Green in the Abingdon catalog), with a tan interior (Autumn Leaf,
again), and sported silver-painted 48-spoke wire rims.  They were held
on the car with octagonal "safety" knock-off nuts, introduced when the
world went crazy in about 1968 or so and decided that any part of a car
that might possibly cause injury -- such as the switchgear, the
dashboards, and the bumper overriders -- needed to be made as safe as
possible.  But that's another story.  These octagonal nuts were loosened
and tightened with a special wrench, or spanner, with a matching
octagonal hole in one end, and a lead hammer provided in the boot of
cars with wire wheels (also useful for restarting the fuel pump if it
quits on the road).  Later, I replaced the octagonal nuts with proper
eared knock-offs, about the time I replaced the car's matte-black grille
with a proper stainless-steel grille.

Now, wire wheels using the Rudge-Whitworth mounting mechanism -- such as
those on M.G.s, as well as most British sports cars -- rely on a splined
shaft on the car, with a tapered seat at the hub side of the shaft. 
Matching splines inside the hub of the wheel itself grip the splines on
the car, and the wheel is held in place with a large nut (no, not the
one in the driver's seat, which may be either on the near side or the
off side, depending on which side of the pond the car originates).  

One of the bits of maintenance required by wire wheels is the semiannual
removal of the wheels for cleaning and re-greasing.  To keep the wheels
from rusting solid onto the axle stubs, a thin film of axle grease must
be inserted between wheel and stub.  Doing this involves removing the
wheels, wire-brushing any rusty old gunk from the splines, and
reinstalling the wheel.  This involved banging on the knock-offs while
the car was still on the ground so that the nuts would loosen, then
jacking the car up and removing the nuts, then the wheels.  I used to do
this in the spring, and then again in the fall -- or, in California, at
the end of our rainy season (to remove any trapped water) and at the
beginning of the rainy season (to help ensure against trapping any
water).

I can in fact verify that the wheel nuts on each side of the car were
NOT interchangeable -- you could swap front to rear on the right side or
on the left side, but not right-to-left.  The left-hand nuts were
reverse threaded, just as the left-hand lug nuts on my '67 GT Junior. 
The theory was that braking torque would *tighten* the wheel nuts rather
than *loosening* them.  The practice was that you banged on the
knock-offs in a *clockwise* direction on one side of the car, and a
*counterclockwise* direction on the other.

Which side is "near" and which is "off," I have no clue.  I *do* get on
and off a horse from the left side, but that's another story too.

- --Scott Fisher

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