7/16" lug studs and 1/2" holes in rotor

[65 drop top]

Upgrading to Wilwoods on my 12 bolt rear. I previously bought new axles with 7/16" lug studs. Just got the new Wilwoods and noticed the rotor hat is drilled for 1/2" studs. Is it ok to use as is? Is there a bushing/insert that I should use? Thanks.

[rickpaw]

You should be fine. The rotor centers on the axle snout.

[Apogee]

You should be fine. The rotor centers on the axle snout.

X2, the rotors should be hub-centric, justified on the center registers of the axle shaft, not lug-centric. If the rotors are not hub-centric, then you should add hub-centric rings so they are. The use of bushings to make rotors lug-centric is an exceptionally poor practice IMO.

Tobin
KORE3

[65 drop top]

Ok thanks, that's good news. The rotors did come with the hub centric rings. My concern was that if I hit the brakes hard that the rotor could slightly rotate since there is some slop in the holes. Is torquing the wheel down enough pressure the keep the rotor from slipping. Thanks again.

[Apogee]

Ok thanks, that's good news. The rotors did come with the hub centric rings. My concern was that if I hit the brakes hard that the rotor could slightly rotate since there is some slop in the holes. Is torquing the wheel down enough pressure the keep the rotor from slipping. Thanks again.

Yes, the clamping force between the wheel and the axle flange is supposed to be adequate such that the rotor cannot "slip". If the rotor can "slip" as you describe it, then you're either not torquing your wheel studs correctly or they're undersized for the application. Most pro-touring applications really should run M12x1.5 or 1/2-20 studs IMO from a design perspective, but 7/16 studs are generally fine, they'll just have lower factors of safety. Larger studs equate to higher lug nut torque which equates to greater clamping force between the wheel and axle which means larger factors of safety.

Tobin
KORE3

[TheJDMan]

Personally, I would not run 7/16" studs! It is a relatively simple matter to re-drill the axles and install 1/2" studs. Much safer!

[Skip Fix]

That "slip" is always something I worried about too, yes clamp "should" hold it but tighter would leave no room to have any motion. Have a small bushing made if you are really worried . Heck Chrysler had one side lug nuts with left handed threads so stopping always tightened them-engineers must have though that was a potential issue but then they just used slide rules and not calculators/computer back then

[65 drop top]

Just found out that my axles came already drilled and tapped for 1/2" screw in studs as well as the current press in 7/16". So I'm just make the switch as I can do it easily and at home. Anybody know the torque spec for the ARP screw ins? I plan on using loctite, not ARP lube. Thanks.

[Apogee]

Just found out that my axles came already drilled and tapped for 1/2" screw in studs as well as the current press in 7/16". So I'm just make the switch as I can do it easily and at home. Anybody know the torque spec for the ARP screw ins? I plan on using loctite, not ARP lube. Thanks.

I don't think ARP offers torque specs for their universal screw-in studs, however you could call and ask. If you're using threadlocker, we typically torque them to 75-80 ft-lb and call it a day. For the lug nuts, I torque dry to 95-100 ft-lb on the ARP 1/2-20 stud on my rides, or about 90 ft-lb with anti-seize.

Tobin
KORE3

[High Plains Mopars]

Heck Chrysler had one side lug nuts with left handed threads so stopping always tightened them-engineers must have though that was a potential issue but then they just used slide rules and not calculators/computer back then

So did Buick, Olds, Pontiac, Cadillac, and Studebaker. But Chrysler held out on using them longer than anyone else.

[MonzaRacer]

Silver/Nickle based antiseize will not change the stud torque more than 5% and that's on new studs with no extended use. As studs get used, the studs will deflect the threads slighty, this can obviously make differences.
Copper or green colored antizeize is not recommended for use on non heat exposed components.

[iadr]

So did Buick, Olds, Pontiac, Cadillac, and Studebaker. But Chrysler held out on using them longer than anyone else.

And BTW, Left hand threaded wheel studs had nothing to do with braking.

A wheel nut endures planetary-gear-like torque, every day, all the time, even coasting.
And if a nut is loose- or nearly so- you have a problem.... LH threaded studs are specced prevent them from working loose.

[Skip Fix]

That was the explanation I heard years ago. And my old Road Runner in college had some work loose that I must not have tightened so the theory either way did not help.