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03 CTS 3.2L (Sold) / 09 CBR 600rr /2014 GMC Sierra
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Discussion Starter #1
so this isnt on my cts but it is the same part number(had to change one on the cts because it was cross threaded last year) and im not on any forum for my truck so...here it is...

went to change the brakes on my 2002 jimmy yesterday... my dad went to take a wheel off and the stud snapped off within 1/2 turn to loosen one lug...
so my friend came to help got it all appart, replaced the stud, swapped the pads all back together... torking the lugs to 80fp (i usually torque them at 80 then drive around the block and re-torque to 95fp) and SNAP... another one just broke off... my torque wrench is bran new and barely any pressure on it it was probably at about 60-70 fp if even that.....

so any ideas what would cause this? it just blows my mind how easily they broke....little scared....

i am getting 4 more studs for that wheel and putting them in so it will have 5 bran new ones...they are about $6 each so i dont want to go replacing them on all the wheels but its tempting. if i can find them for cheaper ill grab them all and swap them.
 

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2003 CTS "Ebony Maria" 2005 Cadillac STS "Grace"
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6,414 Posts
are they factory wheels on there or aftermarket? if it is aftermarket wheels, then you need hub rings to compensate for the small gap between the hub and rim itself. this will cause the lug nuts to sit improperly and snap them when you try to remove them because they become brittle over time...
 

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03 CTS 3.2L (Sold) / 09 CBR 600rr /2014 GMC Sierra
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Discussion Starter #3
factory wheels... i did put wd40 on the them last night after the 2st one broke... hoping to loosen up any possible rust
 

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2003 CTS "Ebony Maria" 2005 Cadillac STS "Grace"
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6,414 Posts
that will help as well...since they are factory, have you ever rotated them?
 

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03 CTS 3.2L (Sold) / 09 CBR 600rr /2014 GMC Sierra
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Discussion Starter #5 (Edited)
rotated the tires? yes... ive had a few sets of tires on it. its got 180,000km and runs like new!!!!
im completly blown away that this stud just snapped in half

here is a pic
 

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2003 CTS "Ebony Maria" 2005 Cadillac STS "Grace"
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6,414 Posts
the last time you had your tires rotated, they must have not evenly tightened the nuts...that would cause your wheel to sit a bit awkard and cause extra pressure on the stud
 

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2006 STS V8 AWD, '95 Ford Ranger
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29,091 Posts
Loose wheel studs flex back and forth until they snap off like bending a paper clip in two.
 

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05' CTS
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60 Posts
more then likely some numb nut used an impact gun to torque down the wheel some time in the past, easly hitting 3-4x the torque spec even with the smallest gun.

When you torque a bolt you stretch the bolt slightly if you go over spec you take the bolt into a plastic state where the stretch becomes permanent and it's a short trip to complete failure past that.

As far as the comment about needing wheel spacers to avoid a bad joint design, since s-15 came from the factory with steel wheels they already came with the worst case scenario, and any alloy wheel would increase the length of the bolted joint decreasing the stress for the same clamp load.
Also I noticed you were using penetrating oil to loosen the nuts make sure you clean that off prior to torquing, the reduction in friction causes a major increase in clamp load when applying the same torque.

If you want a do a quick check clean any crud off the threads spin the nuts down on the studs. You should be able to do this with out a wrench(at least on the second try). If there is an issue use a thread checker to see if you can spot elongated sections of threads near the base. Those should be replaced now, if they check out the stud is not likely to snap anytime soon.
 

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03 CTS 3.2L (Sold) / 09 CBR 600rr /2014 GMC Sierra
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Discussion Starter #10
Thanks for the info, I have a feeling that it is streched threads.. The shop actually warped my bran new rotors because they over torqued the wheels, and the lugs did not go on that easily even with the oil on them.
I will be replacing all the studs on that wheel and then looking online for a better price on the studs so I can replace the other 15 and not have to worry about it.
My jimmy actually has factory alloy rims on it, they sure are ugly though and I don't have the center caps for them. The back 2 wheels were siezed on, my dad used a 10 foot steel fence post as a prybar to knock them off... At one point I almost gave up and thought about sellin it as is for cheap lol...

If anyone has a link to where I can get more of these please send it this way, I searched gmparts dirrect but couldn't find them, even with the part # search.
 

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05' CTS
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I don't have a part number but like you noted these are really common studs. I wouldn't hunt to hard for name brand super duper studs. Years ago when i was racing we would just keep a few in the trailer that we picked up from any auto shop, they lasted about as long as the ones the from the speedshop. The only difference was we would have to bevel down the tips for easier rundowns. We would keep them in use until they broke or we noticed the threads were stretched during the Monday teardown.

Have you ever taken your Jimmy offroading? I never got to into the rock crawling but they kick the snot out of most others flying down a trail, great balance when you get air. It would fly just a little nose high but it settled down with out bouncing like the pickups. I did play with the suspension a bit with a 3" lift new springs out back, new A-arms up front and Matching Ranchos.
 
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