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Re: TR-3 Wire Wheel conversion

To: Triumph Mailing List <triumphs@autox.team.net>
Subject: Re: TR-3 Wire Wheel conversion
From: Michael Marr <mmarr@execpc.com>
Date: Fri, 16 Aug 1996 13:04:32 -0700
Organization: Proven Alternatives Inc
References: <960816095106_180394664@emout15.mail.aol.com>
ArthurK101@aol.com wrote:
> 
> In a message dated 96-08-15 14:33:40 EDT, twakeman@scruznet.com (TeriAnn
> Wakeman) writes:
> 
> << Using a lead hammer, not copper, pound the living daylights out of the
>  knockoff untill it refuses to turn any more. >>
> 
> NO! NO!  definitely not the way to do it.  This is not necessary and can
> result in damage to the hub or wheel.  The correct way is:
> 
> With the tire off the ground
> 1) Ensure that the knockoff is on the correct side of the vehicle (the
> knockoffs and the hubs are threaded differently for the right and the left
> sides).
> 
> 2) Screw the knock-off on snugly by hand then, then give about 5 or 6 medium
> strength taps with the lead hammer.
> 
> 3) Then drive several miles.  The centrifugal force on the knockoffs will
> tighten them down properly.
> 
> They are designed to tighten as you roll. That is why they are "side
> sensitive".
> 
> Art Kelly '64 TR4 CT33118L

Because centrifugal force acts radially, it will NOT tighten the nuts as 
you roll.  I remember reading a long series of correspondence on this 
subject in an English engineering magazine, I believe, in which several 
theories were offered but none were agreed upon as being true.  One of 
the points that was agreed upon was that relative movement between the 
wheel and the hub would tend to tighten or loosen the nut.  The question 
is, is the relative movement predominantly in one direction or the other? 
 In other words, does braking torque or acceleration torque predominate? 
 If braking torque is the predominant torque, then the nuts on the left 
side of the car (driver's side in the USA) should be threaded 
counterclockwise and the right side clockwise.  If acceleration torque is 
the greater, then the opposite would be true.  If I were designing a car, 
I would assume that braking torque would be the predominant torque 
experienced by the knock-off nuts, because I think we tend to brake 
harder than we accelerate, so I would put counterclockwise threads on the 
left and clockwise on the right.  I can't for the life of me remember 
which way my TR3 is set up - I shall check it out tonight!

As for the degree of pounding required, I think I would agree with 
TerriAnn.  The tightening torque for a 2.5" diameter bolt has got to be 
in the 250-300 ft-lb range (I shall look it up in my "Machinery Handbook" 
tonight) and, without doing the math, I bet the impulse of a 2lb hammer 
swung through a 2 ft radius at 5-6 ft/second acting on the ear of a 
knock-off would result in a tightening torque approaching those values.

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