Wheel Torque

[QSHIPQ at aol.com]

Berme:
Comments inserted
In a message dated 10/22/02 12:35:02 AM Central Daylight Time,
b.m.benz at prodigy.net writes:


>Ah, come on Scott!  You must be kidding!  Your torque wrench knows if it is
>torquing a lubed or dry bolt and thus reads differently because?  BS!
>If your wrench reads 100 '#, its 100'# applied to a wet noodle or a head
>strong bolt.  Too much KY on hand, Scott?

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?

I spent a lot of time researching this since last week.  Right now, I can't
find ANY wheel or car manufacturer that recommends the use of ANY lubricant
on lug/wheel bolts.  Several TSB's (in a plethora of vehicle industries) have
been issued regarding the specific procedure of making sure threads are clean
and nick free, and expressly stating that *no* lubricant should be used on
the threads and/or (especially) the land area of the nut/bolt.  Ford seems to
have the highest number of "issues" with wheel bolts, including a recall on
excursions for backing out problems, and a specific TSB (a ford focus TSB) on
the use of lubricants/coatings on the land area of the bolt.

I'm waiting on some of the more nerdy publications to come in, and I'll file
a better summary.  Right now, the documentation seems to support the summary
that those that are using any flavor of lubricant on wheel bolts *don't*
appear to be in the mainstream consensus, and are overtorquing wheels by
definition.

Personal experiences aside, this procedure of applying A/S appears to have
some bigger antichrists.  WRT racing, I'll chuckle some at the claims of some
unknown "pro instructor".   E Fittipaldi (hopefully not with his own brand)
not only lost a wheel bolt, it cost him a DNF (shot into the trans sump).
Audisport even lost a couple in the rally days.  The documentation of
wheel/wheel bolt failures in racing is pretty high.  in fact, regular
inspections of wheels for stress cracking is commonplace, and several
companies (in a town near you) offer this certification service.   Many
sanctioning bodies actually have rules for wheel re/certification.

ALL Wheels/bolts/nuts/studs have a service life.  In normal driving this can
exceed the life of the cars mileage several fold.  In extreme environments
(including even marque track events), that service life decreases
exponentially.

Thanks for the input Bernie.  I agree, and the documentation supports your
contention that wheel flex and distortion are probably the cause for my
wheel/bolt loss.  Since that initial statement, you are straying further from
the mainstream consensus on the subject of wheel/bolt.  My "clean,
inspect/replace and (re)torque" (CIRT) recommendation IS the mainstream,
period.

If you aren't going to routinely CIRT, then it's all up for grabs.  A
lubricated bolt might be better than a galled, pitted, dirty install - I
won't speculate on that.  But that (lubricated) wet torque changes other
variables in the mix, since an overtorqued wheel is in an extreme environment
by defintion.

HTH

Scott Justusson