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Re: lug nut torqueing(again probably)

To: team net <autox@autox.team.net>
Subject: Re: lug nut torqueing(again probably)
From: "Mark J. Andy" <marka@telerama.com>
Date: Tue, 8 Jun 1999 13:32:17 -0400 (EDT)
Howdy,

On Tue, 8 Jun 1999, Robert & Katherine Seamon wrote:
> Here are some lug nut torqueing questions:
> 1.  Why do you apply more torque to larger nut sizes?  I would think smaller
> nuts need more oomph to hold a wheel on.

No. The reason is that the wheel stud (or bolt or whatever) is streched
just a bit when you tighten the nut.  It stretches just enough to act like
a rubber band in that it keeps trying to snap back.  When you loosen the
nut, the stud dgoes back to the length it was.  If you overtighten the
nut, the stud stretches past this level and deforms (and is now junk, even
if it doesn't break immediately).  Smaller nuts tend to be on smaller
studs, and since there's less material in those studs, it takes less
torque to get them to stretch the proper amoutn.

> 2.  Does 13/16" sound like a correct size for a Ford lugnut?  It seems to
> fit perfectly on my ZX2, but there is another size on my 3 way that seems to
> at least fit on the nuts well enough to spin them quickly.  Unfortunately
> none of the markings, if there were any, on my 3 way spinner lug nut wrench
> are legible.

In general, using the tightest fit you can is the best way to go.  13/16"
doesn't sounds outrageous, but I would try 3/4" as well.  If the socket
feels tight, its fine.

> 3.  What would the proper torque for a 13/16" lug nut be?  TireRack's chart
> only goes up to something like 5/8" or maybe 11/16"

Depends entirely on the material and size of the stud.  Chances are that
tirerack's chart is talking about stud diameter, NOT nut diameter.
Measure how wide the stud is and use that against the chart.  It should
probably be more than 50 lbs-ft and probably less than 125 lbs-ft, but you
really need to get an accurate number.  Look in the service manual (which
should be the only place you get torque numbers anyway, because only the
manufacturer knows what the various bolt materials are.)

> Bonus question:
> 4.  Is lugnut one word or two?

two.

Mark


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