factory wheel stud length

[latrucker]

Does anyone know the length of the factory wheel studs with 4 wheel disc brakes? I am having to use a 1/2" wheel spacer and will need 1/2" longer studs. Want to order new ones before I pull the old ones.

 

[duffymahoney]

What wheels? Aluminum I would do new, steel I would probably leave.

 

[Apogee]

I don't know what EB peeps are using for longer studs, but this conversation seems to crop up pretty often. Whatever you use, you want to make sure that you have 8 full turns of thread engagement (I do 10 due to the fact that the first 1.5 threads forms don't technically need to be full form thread per most fastener manufacturers) between the lug nuts and wheel studs. That's the point at which the threads are stronger than the minimum rated tensile strength of the fastener.

The factory Ford front disc brake studs would correlate to a Dorman 610-219 or 610-277, which are 1/2"-20 x 2" and 1/2"-20 x 2.25" long studs, but both have approximately the same amount of thread since the longer stud has a ~3/16" bulleted nose. With that said, the studs retain the rotor onto the backside of the hub, so they only have a stick-through length outside the wheel mounting surface equal to about 1-1/16" per the '77 EB D44 and '77 F150 HPD44 I have to measure. The difficulty is finding a stud that has the proper sized knurl diameter (~Ø.625") located in the correct place, as the stud goes through the rotor and then the knurl mates with the flange of the hub. I did a little digging around for a suitably knurled alternative stud, and the only similar stud I found was the ARP 100-7707 for $95.99/set of 5, which are 3.05" long.

Or, if you want to get complicated/expensive, you could machine the hub and rotor for another bolt circle, this one tapped to attach the rotor to the inboard side of the hub flange (like a Toyota), and then machine clearance holes in the hat of the rotor for the heads of the wheel studs to seat directly against the inboard side of the hub flange. Not only would this allow one to change rotors without necessitating removal of the wheel studs, it opens up all kinds of wheel stud options to accommodate whatever wheel, wheel spacer combo you might need to run.

Alternatively, if you can tolerate a thicker wheel spacer, you could get custom 7/8" to 1" thick bolt-on spacers and run the studs you have for the inner pattern, and then whatever you want on the outer pattern. Just from a design perspective, if I were to run a 7/8" bolt-on spacer, I would have it made out of steel due to the minimal amount of material between the lug nut seat and inner surface of the spacer, but 1" and thicker tends to be okay with well designed aluminum spacers in my experience.

 

[Yeller]

I’ve had luck going to a Dorman 610-347 however it is 9/16-18 thread, will require new lug nuts and depending on your wheel you may need to just kiss the ID of the stud holes with a 9/16” drill bit, not enough to hurt anything. In my opinion if adding spacers, upgrading wheel studs is not a bad thing. I always upgrade my 5 lug stuff to 9/16, I feel there is a reason the OE’s did that in the 2000’s so I feel it’s a good upgrade, especially if replacing the wheel studs.

Long 1/2” studs always make me squeamish lol. Which is why I feel the OE suppliers didn’t make anything longer. There are some aftermarket racing stuff that is longer but nothing i could find in .625 knurl. ARP number listed above is too small at .618”. In all of the race cars I ever ran we did 9/16-18 or 5/8-11 for faster changes and more strength. If we got hit we wanted the wheel to fold and not come off the car.

 

[latrucker]

Thanks guys, I appreciate the info.