5th Wheel Broken Stud Theory

[zimmysurprise]

Although we are currently running a Class C, several of my camping buddies are pulling 5th wheels. They keep having problems with broken wheel studs with the aluminum rims. They carry torque wrenches and are religious about checking them, but still occasionally break a stud on our trips. We generally write it off to cheap metal studs and heavy trailers, but I have another theory.

They all use those "super grip wheel chock" stabilizers between their tires when parked.They tighten down the threaded rod which pushes the tires away from each other. It holds the trailer still, but there is no torque wrench used on them. Trailer suspensions are designed to have some vertical give as the tires hit bumps on the road, but I don't see much lateral give except the bulge of the tires when you crank one of those chocks down. Is there a chance that continually using these are actually weakening the studs which eventually snap?

They say I'm smoking crack with that theory, but they can offer no explanation why. Please explain to me why this theory is wrong.

[fj12ryder]

Lynnmor wrote:

Bird Freak wrote:
I was a Snap-on tool dealer for about 4 years. If you keep checking them without backing them off first you stretch the bolt a little each time.

Quite the opposite, if the bolt is checked and it didn't move, it can't stretch. If it did move, then you are just doing a proper torque.

But if the torque wrench clicks and the nut doesn't move, that doesn't mean the nut is at proper torque. A bolt/nut needs to be moving to get the torque correct. If the wrench clicks when the nut is stationary, you're looking at static friction, not necessarily proper torque setting. The bolt/nut has to be moving when the wrench clicks.

[zimmysurprise]

zimmysurprise wrote:

They say I'm smoking crack with that theory, but they can offer no explanation why. Please explain to me why this theory is wrong.

Thanks for all the responses, especially BB_TX and Old Biscuit who directly addressed my question. I think their explanations are valid, that vertical pressure of 3000# + pounding down the road and side loading torque are most likely at play.

I'm less convinced that the brand of torque wrench is the cause or that I know the only two guys who ever broke a wheel stud on their campers but thanks for your opinions.

[Lynnmor]

Bird Freak wrote:
I was a Snap-on tool dealer for about 4 years. If you keep checking them without backing them off first you stretch the bolt a little each time.

Quite the opposite, if the bolt is checked and it didn't move, it can't stretch. If it did move, then you are just doing a proper torque.

[Bird_Freak]

Durb wrote:
Do your buddies use cordless impact or air impacts when installing their lug nuts? They could be over torquing the studs from the outset and the torque wrench is just a placebo. A torque wrench has to move the fastener to be accurate.

This is true. I was a Snap-on tool dealer for about 4 years. If you keep checking them without backing them off first you stretch the bolt a little each time.

[ktmrfs]

Harvard wrote:
Different coefficient of expansions may also be involved.

given that a very large number of cars/trucks come with aluminum wheels and there doesn't appear to be any issues in cars/trucks, I doubt that has any effect.

[Lynnmor]

Cummins12V98 wrote:
Maybe it’s the use of all these quality Harbor Freight torque wrenches. 😉

I've never seen a good test that showed the HF wrenches off by an appreciable amount.

Just One

[wa8yxm]

I have broken a stud or two over the years. First one was on a FORD F-350 Custom 10,000 option (those are BIG Heavy Lugs) and it snapped like a toothpic.

They are are multiple types of torque. Rotary they are fairly strong. likewise straigit out and there is not much "Side" torque applied by the wheels (They really don't carry that much load the center hole/hub carry the weight)

But try to bend 'em and SNAP Like I said "like a toothpic" (Think of how you snap one)

The Torque wrench usually has the socket at one end and the force at the other end so it not only twists but bends like the toothpic

A 4-way or an impact wrench are 100% rotary force if done properly.

Oh to break the lug on the F-350.. I used the 2-piece lug wrench under the hood. and shoved the rod all the way through so it worked like a torque wrench.
The other lugs I balanced the rod so I put only rotary force on 'em.

The Next change was done by the tire guy.. and he had a hard time getting 'em off cause ... Well I'd over torqued them just a little when I put 'em on.

[Nv_Guy]

dougrainer wrote:
I have probably serviced and we have sold Thousands and thousands of 5th wheels and regular towables over the years. Maybe I have seen 2 or 3 with broken studs over the 30 year we sell and service. So, if you have a few buddies having this problem, then it is something THEY are doing. Doug

X2, I don't think I have replaced more than that as well.

My WAGs as to what they are doing
1: Cheap torque wrench
2: They are using the wrong wheels -should be hub pilot but using
stud pilot.
3: Improper torque sequence. Not tightening things down evenly
4: Going nuts with impact gun- all friends using the same tire shop?

[Durb]

Do your buddies use cordless impact or air impacts when installing their lug nuts? They could be over torquing the studs from the outset and the torque wrench is just a placebo. A torque wrench has to move the fastener to be accurate.

[Cummins12V98]

Maybe it’s the use of all these quality Harbor Freight torque wrenches. 😉

[Cummins12V98]

azdryheat wrote:
I've got 3 axles and have never lost a wheel stud. Perhaps people are using too much torque.

Never broke a single stud on anything I have owned. Well over one million miles.

[time2roll]

Are these oem studs? OK my story is just cheap materials. My oem drums would always have a squishy feel when applying 105 ft/lb like the bolt was stretching a bit too much. Spec was 90-120 and I was setting them at 105. Never lost a stud but it did not feel right. Fast forward to replacing the drums with disks and it is like night and day. The studs on the discs tighten and click right quick and firm with no extended tightening. Same size stud.

For your buddies I recommend all lugs should be replaced if you replace one. (or just get disk brakes already)

I don't think it is the stabilizer between the tires.

[dougrainer]

I have probably serviced and we have sold Thousands and thousands of 5th wheels and regular towables over the years. Maybe I have seen 2 or 3 with broken studs over the 30 year we sell and service. So, if you have a few buddies having this problem, then it is something THEY are doing. Doug

[schlep1967]

The way I see it is there is only one way force can be applied to only one lug nut. All of the others have to be loose. The one that breaks is the one that's tight.
Tighten them and then mark them with some nail polish. If the polish doesn't line up, the lug nuts loose.

[MFL]

fj12ryder wrote:

bpounds wrote:
People who constantly re-torque things are their own worst enemies.

This is very often the case. To retorque a nut/bolt, the nut/bolt should be loosened and then torqued back to spec. Personally if I was worried about the torque of my lug nuts, I'd dial back the torque wrench to 10-15 lb.ft below the spec and see if they're tight at that setting. If they are I'd call it good.

I like that idea Howard, just backing off a bit to check!

Jerry