Torque for Lug Nuts

Excellent explanation. Thanks for the education.

 

I disagree. Its more like a surgeon saying he doesn't always need to be looking when he makes an incision.
The person in question also told me that in the world of professional Ferrari wrenching not many use common sense.

 

I guess my technique of using a 3' length of 2 X 4 and a ballpien hammer might be flawed???

 

Not at all. That's like a surgeon who has perfected his/her skill and has finess and a more precise touch....and doesn't need to refer to the How To surgery manual every two minutes. It's called skill and experience.

 

Huh? A 14mm bolt is good for about 25,000 pounds of tension?

What specification bolt are you speaking about? If you're not aware, most bolts will take less or more than that spec, depending on grade.

And, perhaps you're not aware that some bolts are designed to be tensioned past their yield point. Most head bolts are of this variety in fact. Of course, perhaps in aviation schoold that's not covered?

The best aviation tech that I know pays very close attention to the metallurgy and spec of the fastenings.

 

Its the axle nut. Think spin on nuts used on old race cars. You torque it high to fully seat the wheel bearings and then back it off and reset to the lower value to set the bearing preload. It gets another bolt to lock it at that location so it cant spin loose.

 

Absoltuely, I used a grade 8 bolt spec as an example. (160KSI for those of you who are engineers). Most of you are not engineers so I didnt dive all the way into the details. FTy for a 160KSI bolt in 14mm diameter is 24,820 lbs in tension but there are ton of variables and caveats in there that I am not going to bother to describe. Fty is engineer speak for load capability for yield strength in tension. I did assume that the wheel bolt is grade 8. 90% of them are. There are standard classes of bolts mostly because even big buyers of bolts dont want to pay to run all the tests to build the strength tables. They run from the 40 KSI range for homedepot carriage bolts to 220-240KSI for high carbon inconel ones.

I am an engineer at Boeing Commercial, I work on the 787 now but have worked on all the airplanes at Boeing over my 30 years here. Working with torquing specs and uses for structural joints are one of the most common tasks we have. Its just what I do for a living.

 

Hi Hal.

Understood. I have tons of respect for you Boeing engineers, absolutely stunning stuff you guys do. I've spent many weeks and months down at the Boeing facilities off Marginal Way there years ago as a senior contractor and was fortunate enough to have several private/vip tours. You know your stuff obviously.

For the forum crowd here it's probably wise to include some discussion of bolt grades/specs - no doubt some folks are using some cheesy Home Depot fastners and expecting them to hold up like a 10.9 or 12.9! I mean, any serious DIYer has to know the basics here if they really want to be considered competent/capable, wouldn't you agree?

Cheers and keep up the good work. Keep kicking Airbus' you-know-what!