Lug Nuts, Bolts, and Life's Lessons

[Johnson David-QA2282 <David.R.Johnson@domain.elided>]

Just weighing in on the lug nuts discussion, sorry if this was covered
already but it was an important safety lesson for me, oh-so-nearly learned
the really hard way (perhaps even posthumously).

Learned this on my wife's 1992 VW Passat, which has wheel bolts instead of
studs.  This may make the problem worse or not, I don't know, but it makes
the solution easier.  The car had made odd rumbling noises while driving for
some time.  I had done multiple safety checks and could never find anything
wrong.  I attributed the rumbling to a worn wheelbearing, and took no
immediate action since bearings do not typically result in sudden
unannounced catastrophic failures AFAIK.  I had always tightened the wheel
bolts with a torque wrench to the recommended setting.

One day my wife was driving the car and noticed the sound get rapidly
louder.  Being a sensible type, she pulled over at the first opportunity
into a parking lot.  Upon turning in, the front wheel promptly fell off,
fortunately at all of 5 mph.  All 4 wheel bolts had sheared off.  Even at
that slow speed, the wheel hit the fender on it's way off and caused
considerable damage to it.  Fortunately this was all covered as a no-fault
accident under my insurance's comprehensive coverage (total cost about
$1200). The hub was not obviously damaged, but the shop that did the repairs
replaced it since this is mandated by the insurance company for liability
reasons.

At the time I assumed either that I had failed to remember to torque the
bolts last time I'd pulled the wheel (unlikely since the couple times I've
done this it has been abundantly obvious during the first test drive), or
the tire shop had overtorqued them and weakened them.  Either way, I figured
the problem was fixed.

Shortly after this experience we noticed that the shop had not centered the
steering wheel properly while performing a post-repair alignment.  AT this
point I was also surprised to notice a slight rumble was still present.  I
told my wife to take it back and have them correct it, since while the
splined steering wheel on the VW is easily aligned, I wanted them to do it
properly and get the rack centered.  The shop broke off all 4 wheel bolts on
the <other> side trying to get them off.  It seems the bolts were badly
deformed from the wheel moving around on them, and the threads had got
locked in the hub.  It looks like we had come mighty close to a repeat
wheel-shedding performance.  I elected to have the shop replace the hub,
since all attempts to remove the bolts were unsuccessful.

In questioning how we could have had the same problem on both front wheels
almost simultaneously, we were told the wheels were not properly tightened.
Impossible, I said - I had recently replaced the brake rotors and made
certain the wheels were torqued to spec.  It was then we realized that the
bolt threads had become sufficiently corroded so that when the torque wrench
clicked the bolt was not tight against the wheel.  The resultant repetitive
motion eventually leads to failure of the bolts, with potentially
catastrophic results.

One last interesting item is that I checked the owner's manual to see if
there was any recommendation about using antiseize or oiling the threads to
prevent the corrosion.  There was not, however there was a statement that if
the bolt threads become corroded the bolts must be replaced.  Needless to
say, we now have new bolts on all 4 wheels.  So it was there in black and
white had I bothered to read it.  Yet I can't help but wonder how many
owners have ever read that statement, buried in the section on changing
wheels, never mind visualized the possibly consequences.

I am appalled that such a dangerous condition could occur in the normal
service life of a car - 9 years old, 120K miles is not out of line for a
quality vehicle these days.  It still makes me shudder when I recall that I
drove the VW at a steady 75 for an hour only days before the first wheel
parted company.  I don't really want to acknowledge how bad it could have
been, and how lucky we were.  I have never seen significant corrosion on any
wheel stud installations, not even on my 37 year old 2600 (perhaps thanks to
the bronze nuts and lack of winter use), so I have to wonder if VW made a
poor choice of material for the bolts.  Not only that, but the studs might
at least prevent the wheel from jamming in the fender is it came off, which
at high speed could cause more loss of control than simply driving on the
brake rotor.

Food for thought.  Be careful out there, folks, and learn from the mistakes
of others.  That's just one thing which makes Mr Welty's digest so valuable.

Dave J.
Island Lake, IL
1964 2600 Sprint (dyslexic)
1987 Milano Verde
1982 GTV6 parts for sale

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