Lug nuts backing out?

[APKhaos]

Bone stock wheels, lug nuts, and clean mating surfaces [ok, nice clean rust].
Racing requires careful torquing, and that habit spreads to every car I touch. Scottm is right on the money about the combination of bolt stretch and shock load. Torque a bolt too high and it will fail, but bumping the FSM torque value by 10% or so is not asking for trouble and that's what I'm now doing.
Nice Precision Instruments split-beam torque wrench that gets used for lugs nuts and the very rare repair torque in the 100 - 200 range. Its recently calibrated [that bloody ocd again...]

Its not a mystery question. Not sure why it happens but sounds like its not something others are seeing so I'll just be a bit more OCD with the checks. Its always a rear wheel, but not predictably the same one.

 

[scottm]

I've had a cracked rim that kept losing air and I thought it was the tire, they aren't so obvious. It would take a lot to crack one of these rims, but I don't see how it could be anything other than a rim or hub cracked, or somehow not right. That would worry me. Lugs that are tightened anywhere close to right don't just loosen.

Have you replaced any hubs?

 

[Layonnn]

Mine must be broken then, haha.

I torque mine to 100ft.lbs every time and i have to use a breaker bar and a lot of effort to remove them each time. I actually broke a Snap-On 1/2"->3/8" adapter that i had on my breaker bar to fit my socket on it. So i just bought an impact socket that fit (should have did this the first time, but didn't know it would be that difficult).

 

[nakman]

Always a back wheel, huh? How are your parking brake shoes- any chance you have worn off bits that fell between the hub and brake drum? When you have the tire off, is it easy to wiggle the brake drum? What about just taking the brake off then, and see what's up behind it? maybe there's old gasket material or something that's crumbling... sure sounds like something's moving.

 

[APKhaos]

Always a back wheel, huh? How are your parking brake shoes- any chance you have worn off bits that fell between the hub and brake drum? When you have the tire off, is it easy to wiggle the brake drum? What about just taking the brake off then, and see what's up behind it? maybe there's old gasket material or something that's crumbling... sure sounds like something's moving.

Rebuilt the park brakes a few years back [pre-Mud]. Actuator arms were frozen. Replaced the [original] brake shoes and hardware, so everything is good in that department.
Rear hubs are original. I'll have a good look over the wheels and hubs next time I get a chance.

 

[nakman]

ok so did they ever come loose before you rebuilt the parking brake? Just guessing here obviously, but it sure sound like something is moving back there. 100 pounds should be good to go when everything's in order.

 

[APKhaos]

Yes. Must be my driving

 

[hoser]

How's the rear hub to wheel's hubcentric ring connection? I'd imagine a build up of rust could prevent the wheel from seating all the way. You'd initially get the correct lug torque value and then the wheel would loosen up with some driving.

 

[APKhaos]

That's a good thought hoser. I'll wire wheel the hubs next time I have the rear wheels off. Thanks all.