Why do my rear studs keep breaking off?? They’re torqued to spec!

[Unas2k5]

What can I use to remove those broken studs?
Just my damn luck my car is in this parking lot 30 miles away. Today is suppose to be some stupid holiday I probably can’t get new studs anywhere

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[Unas2k5]

Gorilla or open.

I’ll try the open with ARP studs

 

[Unas2k5]

Do you guys think a local store sells wheel studs that will fit temporarily just so I can get my car home ? Or do I have to drive 3 hours to Ohio to pick up ARP studs today?

 

[shogun32]

A well stocked auto parts store should have dorman studs.

 

[Unas2k5]

I’ve seen that brand. You think you can give me a link to the right ones? I can use them to get my car home and wait on the ARP studs to come in

 

[Unas2k5]

@shogun32

 

[cynicalwill]

Street car/race car receives no mercy. Even my struts are bent.

NOW THATS HOW YOU'RE SUPPOSED TO DRIVE!!!!

 

[Unas2k5]

Do I need a pinch set to remove the broken studs or will they stick out once I remove the rotor ?

 

[Jerry Carguy]

They were torqued to 150 I’m 100 percent sure the entire life span of this assembly !

Retired Ford fastener engineer here. Not sure why spec is so high, it's always been 100 ft/lbs for 5 lug design. If I remember correctly, M14 x 1.5. I would ignore that 150 and back down to maybe 120. You will get a warning if something gets loose, but you won't break the stud.

What is most likely happening is you have stretched the stud beyond its yield point. It can't keep a load on the joint. The stud is now subject to lateral movement which eventually forms a crack. It's as if you never tightened it in the first place. This leads to fatigue and subsequent fracture.

 

[Jerry Carguy]

Also, the broken studs should be analyzed for hardness and/or the presence of hydrogen embrittlement. It happens. I am assuming you have genuine Ford hardware.

 

[Egparson202]

Retired Ford fastener engineer here. Not sure why spec is so high, it's always been 100 ft/lbs for 5 lug design. If I remember correctly, M14 x 1.5. I would ignore that 150 and back down to maybe 120. You will get a warning if something gets loose, but you won't break the stud.

What is most likely happening is you have stretched the stud beyond its yield point. It can't keep a load on the joint. The stud is now subject to lateral movement which eventually forms a crack. It's as if you never tightened it in the first place. This leads to fatigue and subsequent fracture.

I’ve been told the reason for 150 ft-lb rating is that Ford used the same studs and nuts from their truck line. I guess that makes sense, but does that ring true to you?

 

[Jstang23]

Retired Ford fastener engineer here. Not sure why spec is so high, it's always been 100 ft/lbs for 5 lug design. If I remember correctly, M14 x 1.5. I would ignore that 150 and back down to maybe 120. You will get a warning if something gets loose, but you won't break the stud.

What is most likely happening is you have stretched the stud beyond its yield point. It can't keep a load on the joint. The stud is now subject to lateral movement which eventually forms a crack. It's as if you never tightened it in the first place. This leads to fatigue and subsequent fracture.

I'm sorry but the 150 ft/lbs is correct. Anything else you run the risk of loosing a wheel. The ratio of 100 ft/lbs for the M12 studs on the 2005 and back vs the 150 ft/lbs for the m14 is equivalent. DO not run lower torque specs.

 

[Hack]

I've always torqued to the 150 ft-lb spec. I know people say that with anti-seize you will get more stretch on the bolt than you do with a clean bolt. However, I live in the rust belt and I always use anti-seize. I take my Mustangs to the track, so the bolts have seen whatever additional load the wheels and tires can put on them as well.

I've never had a problem and no broken studs. There's something going on with your aftermarket setup is my opinion. I doubt the factory hardware has an issue.

 

[Jerry Carguy]

Not aware of that, but if true the diameter of the stud should be larger than that of a non-truck vehicle. This would require a higher torque spec to achieve proper clamp load on the hub to wheel joint. Result is, a regular car and a heavy truck would each have the same clamp load despite the diameter difference. I don't have access to thread size data between the two. Would be interesting to know. He could do this; take a nut from a standard vehicle and see if it would thread onto his ride. Let us know what happens!

 

[silverbullet85]

I'm sorry but the 150 ft/lbs is correct. Anything else you run the risk of loosing a wheel. The ratio of 100 ft/lbs for the M12 studs on the 2005 and back vs the 150 ft/lbs for the m14 is equivalent. DO not run lower torque specs.

I've installed wheels a 100 times without using a torque wrench on my cars. I'd say the amount of force I use it would be in the 100-120 ish lb ft. Unless you are rally racing your car you won't have an issue and there is no way the lugs are coming off. I'm a mechanic and have never ever had lugs even slightly loose that were installed tight. The problems happen when someone forgets to tighten them at all. Even with lugs that are barley on it would take a good amount of driving for them to fall off, plus you would feel the wheel loose long before it would be in danger of coming off. People look into things that are non issues, just tighten the damn lugs and they won't be a problem

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