Broken Extended Wheel Studs

[Bartman]

I've been using Ichiba extended wheel studs since 2007. To my surprise one broke as I was reinstalling my wheels after purchasing new tires. These were installed on the back of my 73 240Z and I was running 18x9.5 wheels. It wasn't even close to proper torque settings and now I'm concerned about the safety of the remaining studs.

 

Anyone else have wheel stud failures?

[74_5.0L_Z]

If one failed, I would replace them all (maybe consider upgrading to ARP).  For something like wheel studs you want confidence that they won't fail.

[RebekahsZ]

Most studs break from over tightening. Very rarely do they break from the stress of actual driving. Your shop may have over tightened them, then it lost torque as the bolt stretched in failure. I only torque to 75-80#.

[Chris Duncan]

Do a visual inspection of the other studs, you can also feel if they are necked down from overtorque, the diameter will be smaller at the place where they are stretched. If you find some other ones stretched then you have your answer. Visually you may see more space between the stretched threads.

 

The one in the pic almost looks damaged, the break is really jagged. Have you had it in a shop where they took the wheels off for some reason? I've seen techs take a test drive with the lugs loose and it will cause damage.

 

what is your offset and are you running spacers would be the other questions?

Edited May 6, 2017 by Chris Duncan

[Chickenman]

That metallurgy looks very sandy and grainy. That's a sign of poor heat treating or bad materials  . Toss them all. Buy ARP studs. Broke some Moroso 1/2 studs years ago on my Autocross car. Was surprised at that, but again, poor heat treating. Grain structure was all sandy which is really bad. 

 

ARP or factory studs are all I trust now. Don't ever let anyone install wheels with an Air gun. Make them write it on the shop order!! Bust their chops if they even think of it. 

[Bartman]

I agree the metallurgy looks bad, and will likely replace all my studs with ARP. I do all my own work using 5/8" spacers, and tighten by hand with a torque wrench at 90#. Is this too high?

Edited May 7, 2017 by Bartman

[Chris Duncan]

I agree the metallurgy looks bad, and will likely replace all my studs with ARP. I do all my own work using 5/8" spacers, and tighten by hand with a torque wrench at 90#. Is this too high?

 

5/8" wheel spacers?

 

90 ft-lbs is a little high, the FSM for a '76 280Z shows 58 to 65 ft/lbs. Typically a 12mm lug stud can be torqued to 75 ft/lbs. 80 ft/lbs max.

[Bartman]

5/8" wheel spacers?

 

90 ft-lbs is a little high, the FSM for a '76 280Z shows 58 to 65 ft/lbs. Typically a 12mm lug stud can be torqued to 75 ft/lbs. 80 ft/lbs max.

I don't use FSM spec's as my wheels are much larger than stock (275/35 18). I've done some investigation on wheel stud torque values, and as expected there are different values from different sources. It looks like SAE recommendation for 12mm wheel studs is 85 ft/lbs plus or minus 5. Edited May 7, 2017 by Bartman

[Chickenman]

Wheel size should have no affect on stud torquing values. A fastener is designed to be torqued to a specific tension so it doesn't come loose. It doesn't get " stronger " with more torque. Quite the opposite. Over Torque a fastener and it will fail. Some will stretch ( low to medium strength fasteners ) but high strength fasteners may simply shear. It all depends on the material used. Bottom line. Don't over toque, and if you put huge wide sticky tires on... install a larger diameter fastener that can handle more load. 

 

There's a reason why Autocross and Road racing guys upgrade to a minimum of a 1/2 inch high grade fastener. Nascar uses 5/8". That tells you something.  

 

ARP is high grade. Not sure about Ichiban?? Isn't that a noodle??

Edited May 7, 2017 by Chickenman

[Chickenman]

My Audi uses 14mm wheel bolts. Factory specs are 90 ft lbs. Bought some aftermarket extended bolts ( Ceco brand )  for wheels with a thicker flange. Only about 20mm longer than stock to fit wheel flange flange. After 4 years I noticed the aftermarket bolts were getting " Stretchy". Was only Torquing to factory spec of 90 ft/lbs. Obviously, the metallurgy in these left something to be desired. Bolts were on the edge of failure. Fortunately I caught it in time. 

 

Binned them all and replaced with a different brand. But I only Torque these to 80 ft lbs. 80 ft/lbs on a 14mm fastner will still tension the fastner enough to keep it tight. But shouldn't stretch them beyond there yield stentgh. 

[Bartman]

I'm replacing all my rear studs with ARP. I agree torque settings are specific to the strength of the studs themselves and just need to determine the best torque based on these studs. According to ARP it looks like they support at least 98 ft/lbs http://arpinstructions.com/generaltorque.html with the caveat of using their fastener lubricant. 90 may have been to high for Ichiba, but maybe not for ARP.

Edited May 7, 2017 by Bartman