Originally Posted By: Corvette Owner
Well, my neighbor, an electrical engineer, lubed his lug studs and torqued them. A week later, driving to work he heard a terrible noise, stopped his car, thought his transmission was going bad. Had the car towed. HIS LUGS NUTS WERE LOOSE !
I don't know exactly what vette0wner's engineer buddy did... but I'm pretty confident that it was something STUPID... something not spelled out in that anecdote.
I have my own story about stupid engineers and lug nuts. When I was 18 year old... young and dumb, didn't know [censored]... I worked in a small-scale factory that manufactured industrial equipment mounted on trailer skids- in the range of about 4,000 to 12,000 pounds, depending on the setup. These skids were set up to use standard trailer axles and hitches, and one of my jobs was to bolt the wheels onto the hubs. Now, as some of you will know, lug nuts generally don't use an interference thread... you know, 'cause wheels have to come off at some point, and you don't want to damage the stud threads. But the engineers at this company were kinda paranoid about wheels falling off these trailer units- it had happened in the past (can't say why, as I wasn't there). They were afraid that the lug nuts would back off; their solution was to use a
crimped lug nut- i.e. an interference thread. Nobody made one for this application (wonder why?), so these clowns built a jig that we could use in the 30-ton press to crimp our own. Well, you take a poorly designed crimping tool, use it on nuts that were never designed to be crimped, and make some $7/hr. shop-monkey run the press... what do you THINK is going to happen? The results were not uniform. So when installing these wheels, I noted that lots of these lug nuts were [censored] hard to turn. I measured it with a torque wrench. It was taking up to 80 ft-lbs to turn the lug nut... while the spec was 120 ft-lbs or thereabouts. I pointed this out to TWO engineers; it was never addressed. A few months later, TWO wheels came off a 12,000-pound trailer unit (thankfully, not one that I'd worked on). All eight lug studs had snapped on each hub.
Doesn't take a rocket scientist to see what happened here... but it gets better. The chief engineer (not one of the two that I'd discussed the lug nut problem with) addressed this problem by specifying different wheels. He didn't address the lug nut issue (I was pretty disgusted by then and didn't bother to point out the obvious). I actually asked him WHY he'd specified different wheels (I expect the engineers on this forum to see what's wrong with this statement right away... while ya'll mere mortals won't see what I'm getting at):
He said that the new wheels had a greater surface area contacting the hub, and therefore would have more friction against the hub.
I sincerely hope that some of ya'll will get a laugh out of this.
Now that long and only marginally interesting story is to demonstrate this: engineers make mistakes. They are OFTEN wrong. Don't even get me started on warranty campaigns that I've dealt with from assorted diesel engine & heave equipment manufacturers over the years.
So
appeal to authority doesn't hold much water for me when it comes to technical discussions. Or really ANY discussion.