The following message from the named forum reminds me that a lot of people
do not know how to use a "break-over" or "click" type torque wrench. I have
seen countless people pull a click-type wrench to the "click" - which
indicates that the preset torque has been reached - and then pull another
1/16 or 1/8th of a turn past that point. At that point, you are
overtorquing the fastener. When the wrench clicks... STOP! That is the set
point, you have achieved the proper torque. Over torqued fasteners under
stress will break. Of course it doesn't matter much what it is set to when
the wrench has been thrown, dropped, left w/ the spring set to 100# for
weeks on end and other abuse. It is probably no longer accurate. A
break-over or click-type torque wrench relies on a spring under compression.
Just like the springs on a car get sacked out after a number of years of use
and hard bumps, the spring in a torque under constant compression will lose
some of it's springyness. Wind that puppy back to zero after every use and
then compare it to a new wrench evey once in a while to determine if it is
still accurate.
Mike Allendorfer, no longer autoxing but still known to pull a wrench now
and again.
Pasted from http://www.sccaforums.com/ubb/Forum7/HTML/000079.html
>My son runs a 96 Z28 in T2 races and has for three years. We have abrken
many wheel
>studs bith factory and aftermarket studs. The after market studs are weaker
than the GM
>product. We torque no higher than 80#. Also we don't re-torque the wheels
several times as
>that takes the torque setting higher each time. Torque the lug nuts just
once. We also lost a
>wheel at VIR last year and never did find it. If you look in the 2001 rule
book in the T2 car
>specs you will see that the newer model cars are allowed to use a
competition lug nut on the
>GM cars. I wrote a letter to Sven Pruitt asking that all GM cars be allowed
to used this same
>approved wheel stud. It would help if you and anyone else reading this also
wrote to Sven.
>Don't just call, write him. Losing a wheel on a car that goes 130 mph at
mid=ohio can lead to
>a rather drastic accident.
>Also when you put the new studs in the hub be sure that they are fully
seated before you
>then mount a wheeel and get on the track. Torque no higher than 80#.
bobhines
-----Original Message-----
From: Runnion, Ed <Ed_Runnion@regionofdoom.com>
To: 'ba-autox@autox.team.net' <ba-autox@autox.team.net>
Date: Friday, February 23, 2001 7:24 PM
Subject: Lugnut studs
>Check this thread....
>
>http://www.sccaforums.com/ubb/Forum7/HTML/000079.html
>
>As one of the folks racing what is pretty much THE heaviest car at SFR
>events, the above obviously concerns me! I always inspect the lugnuts and
>studs whenever I do a tire R&R, but of course you can't be too careful.
>And being preventative here is obviously a lot cheaper (and safer!) than
>having a catastrophic failure.
>
>The current lugnuts on the car are the GM "standard" 12mmx1.5 threaded
nuts.
>Stock OEM studs in back, SLIGHTLY (but not much) better in front.
>
>I will have the axles coming out soon in back (gear swap), so that'd be the
>obvious time to swap those. And the fronts are really easy to swap as
>well.
>
>So, with all that in mind......
>
>What are the SCCA rules (if any) in Street Prepared on going to :
>
> * Longer wheel studs
> * LARGER (i.e. 14mm, not 12mm) lugnuts
>
>Ideally, I'd like to upgrade to 14mm lugnuts and studs that are approx 1/2"
>longer (I have CLOSE to entire, but not entire, thread engagement on the
>stock lugnuts....about 10 turns worth).
>
>Anyone know????
>
>Ed Runnion Santa Clara CA
>mailto:Ed_Runnion@RegionOfDoom.com
>96 Chevy Impala SS, ESP #984
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