Sheared Lugs

LarryJM wrote:


You make some VERY IMPORTANT and not so subtle points which Turtle evidently doesn't understand when he posted that generic and basically non germane AUTOMOTIVE reference. I can't prove it or provide a authoritative reference, but IMO the higher torque specs for trailer wheels are in fact to cover the sideways/twisting - scuffing in specifically tandem axle trailers. This concern is also why I think it is recommended that one due multiple torque checks (i.e. more than the one typically recommended for normal automotive applications). In fact AFAIK most trailer manufacturers recommend that the wheel torque be checked even like once or twice annually during normal non wheel removal operations.

I will give that automotive article one kudo in their statement that all OEM wheels are hub pilot centered (i.e. HUB CENTRIC) even when the beveled/tapered seat fastening system is used and this "lug centric" nuisance is only found in some aftermarket wheel applications for automobiles.

Larry

Ya, you're right Larry, it was an automotive reference.




Oh wait a sec, here is the exact sticker on "my" trailer which has 1/2" 20 studs. Well would you look at that!!! The EXACT SAME torque value that the "non germane automotive reference" I posted has. :W

And we all know that trailer manufactures use the very best parts money can buy, including aero/space quality fasteners to hold the wheels on don't we? :B After all, look at the aero/space quality frames that Lipert makes. :B

By the way, you're incorrect about higher torque specs on wheel fasteners just because they are mounted on trailers. "Any given fastener" has a yield point. It doesn't mater if that fastener is on a
trailer or a car or a wheel barrel; it has a yield point and you better not exceed that yield point. Now some applications may use a better quality fastener because that is what the engineering spec calls for. But you just can't crank down more on a stud just because it's mounted on a trailer. Or at least you shouldn't.


One things for sure, one of four things happened:
#1. The fasteners were defective.
#2. The fasteners were pushed past their yield point by over tightening.
#3. The fasteners weren't preloaded enough by under tightening.
#4. The fasteners were pushed into an overload situation and failed.

OP, take your pick on the above. It's all a guess which one happened without forensic analysis on the studs.

This isn't my first rodeo Larry. With only 4 bolts holding the whole front end of my race car on, I better know fasteners or I'm a dead man. :E