Wheel fell off

#1

I took my '99 infinity qx4 suv in for a pre trip check up to the daeler, a reliable place. they repacked the wheel bearings and put in a new front axle.(I know almost nothing about cars) the car ran fine on the trip even at higher speeds,65-75 mph. Some 650 miles later, on the way to work, the car begin to make a loud noise and abruptly the L front wheel came off (rim and tire).No one was hurt. the dealer says they think the studs (i.e. bolts holding the rim) were worn

and the nuts came loose and twisted off. (threads on the bolts were damaged). the dealer is replacing the bolts on all 4

wheels. I’ve never heard of anything like this. It is important for me to know if this is possible, I doubt that the dealer was neglegent, they are great people, and I had driven 600 miles since the repairs without any problem. What else could cause this? The wheel is lost in a cornfield, I was going about 55 mph when this happened.

#2

It sounds more like the nuts were were not tightened sufficiently and they gradually worked themselves loose. This happened to me on a tent trailer years ago. The fact that the threads were worn proves that you drove with a loose wheel for some time before the the wheel came off.

SUFFICIENTLY TIGHTENED NUTS AND STUDS DO NOT WEAR OUT!! Unless there is severe corrosion.

The dealer took responsibility for the work and replaced studs and nuts, at no expense to you, I hope. The dealer is a great guy for doing this work free of charge, but the fault lies with his mechanic, I’m sure. However, few dealers will admit this.

#3

Ditto to what Doc said, with one clarification: I’d use the words “properly torqued” rather than “sufficiently tightened”. On studs that have been overtorqued in the past, the stud can actually be stretched at its base and the threads distorted to where the nut tightens before it’s actually providing proper force to the wheel. Lug nuts applied to studs that are distorted can becone loose and fall off in application.

In this case I suspect the nuts were improperly torqued, as Doc said, however I felt it was an important point for people to understand so nobody out there gets the idea that tighter is always better. Proper is better, not tighter.

#4

The way that some manufacturers cheat on hardware like nuts and bolts, it is possible to have stretched lug bolts. Just as I install harmonic balancer bolts with an air impact gun, nobody torques lug nuts properly. Some do, but I think there are still SOME nobodies doing work on cars today. None of the wheels I put on ever came off where the driver lived to tell about it. On the good side, my oil changes have all been good. My oil CHECKING has cost me an engine, but I found the leaking oil pressure sensor and replaced it when I changed the engine. Too late to start caring but…More info: It is easy to install a wheel that is not centered on the lug studs and when it breaks free and centers itself, the lug nuts are loose. The wheel can then fall off. It could have happened that way and broke the lug studs off.

#5

Have this checked by another mechanic before you bring it back to the dealer. The dealer might never admit they did something wrong, whereas if you just bring it to the dealer they will “make the problem go away”.

There may be other damage (rotors, body, etc.), and you should be ready to go after the dealer to ensure they fix ALL the damage (and pay for your towing, etc.).

One other possibility- if they lubricated the outside face of the axles (where the wheel sits against the axle), this can lead to broken studs. However the mode of failure is that they will snap cleanly, and not show wear on the studs like are suggested above. Mechanics will sometimes lubricate this surface, without understanding why it is such a bad idea. If they did lubricate this surface, then ensure they remove the other wheels and remove the lubricants from this surface (brake cleaner usually works well).