Over-torqued lug nuts

I have yet to see any service department use a torque wrench on lug nuts or any other bolts/nuts for that matter. They just use a pneumatic impact wrench that is set at "who knows what?" I also seriously doubt they change the setting for every car they use it on.

Glad to see that you checked yours. Just another thing to keep an eye on. Thanks.

 

If they were torqued to 76 lb-ft it is not unreasonable for it to take 85-90 lb-ft to move them at a later time. How much more or less it take to move them at a later time is dependant on several things. There is no reliable way to check the original torque at a later time.

Torque some clean dry lug nuts onto a clean dry studs to 75 lb-ft, let them sit a day and check the torque required to move them, try some crack-on, some crack-off.
Bolt Science Web Site
I think the guy that wrote that article is a bit of an optimist, but it's still a good read.

All that said, the torque values you found aren't all that bad. If they were looser than spec or 50% tighter, there would be reason for concern.

 

At least they tightened them enough; my dealer forgot to torque three wheel nuts on my car when they rotated the tires at 5k. I decided to check when I found that one of the valve stem caps had fallen off and another was hanging by a thread. I no longer give them any service business.

 

I thought this thread was about Jayman. He's an over-torqued lug nut!



Tom

 

A lot of the time the impact wrenches have torque limiters attached to them. Do different Toyota models have vastly differing lugnut torque values?

 

Impact wrenches ability to control torque are notoriously bad. No way I would use a shop that routinely relied on an impact wrench to set a specified torque.

Torquesticks
Professional torque sticks, sockets, multipliers and extension bars
are several notches above impact wrenches in their ability to control torque. Torquesticks still aren't as accurate as torque wrenches but many people that know what they are doing find Torquesticks acceptable for lugnuts.

 

On a similar note, I like Ron Whites version of his visit to Sears Automotive. Upon leaving, his rear wheel fell off making a right hand turn. "It fell off, it fell off, IT FELL THE F**K OFF!!!

 

When you torque a nut, you are trying to obtain a certain clamping force that holds the wheel against the hub. That clamping force comes from tension in the bolt, which also stretches it like a spring...a very very stiff spring, but it does stretch a tiny bit.

When you apply torque to the nut, some of that torque goes toward stretching the bolt (which you want), some also goes toward overcoming friction in the threads, and some goes toward overcoming friction where the nut face rubs against the wheel.

Some engineer calculated the amount of clamping force needed and the torques (all 3) to arrive at the torque we use when fitting a wheel.

If you undertorque, the clamping force will be low and the nuts might vibrate free. If you overtorque, you overstretch the bolts. If the bolts are overstretched over and over, they harden and can crack. So overtightening can lead to the same failure as undertorquing (a wheel falls off).

Another common problem is that if you use a thread lube (antisieze, oil, etc.) you lower the thread friction. This sounds great, but if you tighten to the same torque, then more torque (and force) will go toward stretching the bolt. This can also lead to hardening and bolt failure. So, you really shouldn't use thread lube, unless you have someone recalculate the tightening torque, to maintain the same clamping force.

 

I have aftermarket lugnuts which are aluminum rather than steel and the torque spec is different as well due to the nature of the metal-metal interface. However the difference is small.

 

Also, I believe that overtorqued lug nuts are not the end of the world since lug nuts are usually not too sensitive to being over torqued, yes I know that the lug nuts have specific torque specs, but lug on some cars, they are suppose to be torqued to 90 ft-lbs.

I'd say not to worry, readjust them and you will be good to go.

 

Last year after having my tires rotated on my Honda Fit I specifically asked them to tighten to spec with a torque wrench. They said ok but when I got up to look out the window at one point I saw the guy tightening the lugs with an air gun. I was upset and when I got the car home I put my torque wrench to max 160 ft-lbs and tried to loosen the lug nuts. The wrench clicked, stating I applied 160 ft-lbs of force, before the lug nuts budged. I had to give it just about everything I had to loosen them. I tightened them to spec but was very angry since I hear it can warp the rotors. Like someone else stated however, I have never seen a shop actually use a torque wrench to tighten the lugs. Anytime I ask about it they give me some story. Once they said the pneumatic wrench is set to 100 ft-lbs although I didn't see anything on the gun to adjust the torque. One guy just said he's been doing it for years and that he knows when to let off on the trigger before it torques too tight. I just can never find a place to take my cars that I feel comfortable with.

 

Discount Tire around here always use a torque wrench and the appropriate setting is on the service sheet so the techs don't have to waste time looking up the proper torque setting.

 

That's how it should be at all shops, but sadly that isn't the case. When I find one that is that way I will be taking my car there. That company took the time to setup a process to do things right.

 

Buy a decent torque wrench and do it yourself. I made the mistake of taking my evo to a mitsu stealership to have my rotors turned because I had some pretty uneven pad deposits. Usually I do everything myself, but I had no way of getting the rotors anywhere if I took them off my car, and they would be too heavy to put in a backpack and take the motorcycle because they are huge.

The tards over-torqued the lugs so badly that I broke 1 ratchet and one breaker bar trying to get the FIRST lug off. When I broke the breaker bar, the little ball and spring that positions the chuck at different angles shot out and hit me in the face.ound:

First time I had someone do maintenance for me and it bit me in the nice person. Never again...

 

If they are talking about a torque stick that is used on a air ratchet - those are notorious for being inaccurate and are not recommended when you want a precise torque set.

Torquing of lug nuts should be done by hand with a wrench that is periodically calibrated.

 

Torque sticks work (in theory) if:

the same impact wrench is used (not a bigger one)
the same air pressure is used
the same power knob setting is used on the wrench
the impact wrench is in the same state of lubrication

It's not a magical device that transforms any impact wrench into a calibrated torque-delivery machine.

Since almost the above conditions are never met all the time at a tire shop, they are unreliable, no matter how good the salesman is nor how many other shops use them.

As far as I'm concerned, they're snake oil.

 

Also, Permatex anti-seize is your friend!