I have heard that the studs on the cobalts are made of aluminum and that you have to torque the wheel nuts to 100ft pounds, as recommended by GM, and if you torque them any tighter you could warp/bent the stud?

 

Not so much warp or bend. But more like stretch the bolt and weaken its structural integrity in the process.

 

they arent aluminum, they are steel. and all wheel nuts need to be torqued properly. a general rule of thumb is 85ft/lb on aluminum car wheels, 100ft/lb on steel car wheels, and 6 lug or more truck wheels are 140ft/lb. however as stated, thats a rule of thumb, its best to get the actual spec for the car.

 

If you improperly torque the whel studs you can cause lateral runout in the brakes, creating a pulsation. you can also weaken or break the studs, under torqued wheels will work free.

 

Thanks for the info folks! I Put on new rotors and new rims and have this vibration when I apply the brakes. (tire shop used an air gun to put them on) I'll take the wheels off and check the measurement of the studs to see if they are in spec and replace them if they are out of spec, then re torque the the wheel nuts to 100ft/lb. as per GM spec guide. I'll let you guys know how this works. Thanks again for your help!

 

make sure you dont have the little star washer rotor retaining clips on still....aftermarket wheels dont like those.

 

Arent they called Tennerman nuts?

 

Yes I think technically they are TinermanPalnut pushnut bolt retainers. I didnt really feel the need to type that.

 

Word, I thought I remembered that from my brakes class.

 

they are "pushnuts" Tinnerman is like Kleenex, its just the most common name brand version.