Wheel Torque

Bernie Benz b.m.benz at prodigy.net
Tue Oct 22 09:27:02 EDT 2002

> From: QSHIPQ at aol.com

> Bernie, maybe you ought to take some time to look thru some of the available
> material - there is a lot.  My wrench isn't the issue, the bolt/nut and the
> wheel are.  If you increased the clamping force (an earlier claim) that can
> cause bolt stretch, stud stretch, wheel cracking, and failure of
> fastener/wheel.  Think of it as tensile strength.  You can increase it either
> by lubricating or torque up to a point, the consequenses of the unknown
> "beyond" is the problem.  The reason for wet torque specifications and dry
> torque specifications.  A wheel bolt is a dry torque specification.
>>> "since the "backing" out isn't necessarily a A/S problem."
>> Up to this point no one has proposed that the root problem is the backing
>> out of the bolts, at least not before the clamping force has been reduced to
>> zero by another active mechanism, creep of the aluminum wheel material.
>> Don't go out on this limb, Scott, until you have scribed a felt marker line
>> across the bolt head and wheel, such that you can check for bolt unwind
>> rotation just before you have to retorque.
> Well, I just don't see how all my bolts fell off without the obvious.  I
> don't need a scribe.  They didn't break, the threads were intact, the bolts
> were found within 20 feet of each other, and the wheel fell off.  The scribe
> seems kinda...   moot?
Scott, you miss my point.  It being that the bolts/nuts do not back off
(unscrew) as long as they are providing an appreciable clamping force to the
joint, maybe down 25% of your initial torquing.  I was suggesting that you
could verify this with a mark during your frequent retorquing of the same
joint after initial installation.

Of course, after the clamping force has reduced to the point of equaling the
cornering forces on the fastner the mechanism changes and the fastner may
well unscrew, resulting in the loss of a wheel.

Do you think that we have beat this to death yet?


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