Breaking wheel studs

It sounds like one of three possible things:

1. Your torque wrench is out of calibration, and 120 lb-ft of torque is actually significantly higher. In my manufacturing days, we would have every torque wrench calibrated every six months. It was not uncommon for them to be significantly out of calibration.

2. The specified torque is too high. I'd get the lug nut/stud size and see if there are some charts that specify torque. Your local tire shop may have the specs.

3. The studs have a manufacturing defect and all of them should be replaced.

One other possibility that I just thought of. If a shop used a pneumatic gun even once on the lug nuts, they could have fatigued the studs with an over torque situation and they all should be replaced.

One other thought to consider is that if you have aluminum rims, 120 ft/lbs may be too high. The aluminum will creep if overtightened and you will loose torque. I've observed that many aluminum rims have a lower torque setting than the steel rim equivalent. What is strange is that in my experience, most of the other lug nuts would have to lose torque for to cause a loose wheel to stress and begin breaking lug nuts but you're reporting that none of them are loose.

I'd wager you have a grossly out of calibration torque wrench and are over torquing the lug bolts (?). I found that my torque wrench was almost 30% out of calibration (too low). Harbor Freight sells what we used to call a "torque watch." You can put one end in a vice and your torque wrench on the other end and verify if your wrench is in calibration. You can also use the torque watch to put on the end of a non-torque ratchet and torque your wheels that way. Very helpful tool. Here's a link for the tool:

http://www.harborfreight.com/12-in-drive-digital-torque-adapter-68283.html

After losing a wheel on the interstate, I'm paranoid about this subject. If you think you've stressed the other lug bolts, you may want to consider pounding out all the old ones and starting with new bolts, properly torqued.


Good luck,
Phil

TucsonJim wrote:
One other possibility that I just thought of. If a shop used a pneumatic gun even once on the lug nuts, they could have fatigued the studs with an over torque situation and they all should be replaced.

4. What TucsonJim said ^^^! Chris

120 PSIG was the correct torque for our previous 5th wheel that had aluminum wheels and 9/16' studs. Typically, if studs are breaking as you describe, they have been overtorqued at some time in their life, either with an impact wrench, an out-of-calibration torque wrench or a breaker bar.

Rusty

I don't worry about torque. I cant budge mine any tighter. The is tight enough. They came from the dealer this way. Why keep messing with them if they are already tight? Sounds like yoy are fiddling with something that does not need fiddling with Resulting in over tightening and breaking.

Another thing to check is make sure your lug nuts are the proper ones for your wheels. The angle of the bevel needs to match that of the wheel. The wrong lug nuts can cause stud damage.

Thanks for the responses.

Actually aluminum wheels require a higher torque level than steel wheels.

I think at this point I need to check the wrench. Wheels have not been removed for some time (for new tires over a year ago) and I watched them use a torque wrench.

jkwilson wrote:
Another thing to check is make sure your lug nuts are the proper ones for your wheels. The angle of the bevel needs to match that of the wheel. The wrong lug nuts can cause stud damage.

Happened to me. I was slowed for traffic and heard an unusual noise. Two broken studs and the rest loose. Taper w as correct but the hex portion of the nut was larger than the recess so the hex hit before the nut seated.

RustyJC wrote:
120 PSIG was the correct torque for our previous 5th wheel that had aluminum wheels and 9/16' studs. Typically, if studs are breaking as you describe, they have been overtorqued at some time in their life, either with an impact wrench, an out-of-calibration torque wrench or a breaker bar.

Rusty

Whoops...you mean 120 lb-ft for the torque. You need to go ahead and retire Rusty.

And Dutchman Sport, you need to get a torque wrench and check your wheel lugs. With my aluminum rims, it takes three retorques to get the lug nuts to stay tight.

All it takes is one over torque to possibly take the lug bolt beyond its yield strength and the bolt is set to fail at any time.

Ken