Breaking wheel studs

[Wind_Surfer]

Thought I would ask the collective for help.

I have now had 3 lug nut wheel studs break. Rig is a 34ft, 14,400 GVWR with 16 inch 8 lug aluminum wheels, studs are 9/16"dia. Studs have broken only on the passanger side, two broke on the front and one on the rear wheel. Torque specs are ~120ft lbs. I have a nice torque wrench and check the lug nuts before each trip and during a trip if it's a long haul. What I notice is that a nut won't torque up and of course it has broken. Seldom do the nuts need tightening.

Any ideas on why the studs are breaking?

[SDM]

Are these Dexter 7000# or 8000# hubs? Had same problem with lugs bolts and torque. Ended up at 120#. I have 16" eight hole alum wheels. Replaced wheels and hubs and have not a problems since.





















3

[pbar34]

Wind Surfer wrote:
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.

I am curious your source regarding Al wheels requiring more torque than steel? I have heard this before but the sources I've checked in the past, in addition to a lot of stories regarding cracked alloy rims due to over torque, has always led me to believe that Al rims will usually have a lower or equal torque to steel but not higher. Below is one source that I trust. Take a look at the table on this and compare the steel vs. Al wheels. If you have another source, please share since it is good to debunk any myths in this area (especially if you've ever lost a wheel at 60 MPH…).

http://www.etrailer.com/question-75604.html


Phil

[RustyJC]

TXiceman wrote:

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.

Blame it on a bad Monday at work (there's that word again!!)

Rusty

[TXiceman]

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

[Charlie_D_]

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.

[Wind_Surfer]

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]

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.

[DutchmenSport]

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.

[RustyJC]

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

[Me_Again]

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

[pbar34]

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]

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.

[TucsonJim]

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.