# lug nut question



## Chris-Austria (Dec 23, 2010)

Hi!

I need a general information on lug nuts.
My studs are 7/16" and the nuts are 7/16-20RH. (the -20 says that 20 turns = 1"?)

How many turns are needed to secure the wheel?
Because with the stock lug nuts I can make at least 6.5 turns with my Cragars or 10 turns with the Welds (shank lug nuts). If I now put spacers on the Welds (0.25") I can turn them about 7.5 times. Is this enough? And should I worry about the Cragars??
My stock GTO wheels make 9-9.5 turns and my Cadillac makes 8 turns with stock wheels.

One turn is 360°, the lug nuts have "7/16" stamped on one side.. so I turn it until I see the stamped side again and that is one turn (for me).

Is there a difference in how many turns I need between shank style and acorn style lug nuts? If there is.. please let me know how many turns are needed with my stock rims and Cragars (acorn) and with the Welds (shank style).


----------



## voltaire (Aug 23, 2013)

The general rule that we use is to make sure there’s at least 1/2-inch of thread engagement for 1/2-inch and 12mm diameter lug studs, and 5/8-inch engagement for 9/16-inch and 14mm diameter lug studs. To be on the safe side I would want more than 1/2"/ 1.5cm of thread engagement. If you are drag racing you should have at least 1/4" .5cm threads showing on an open faced lug bolt.


----------



## ALKYGTO (Mar 29, 2010)

NHRA rules (National Hot Rod Association) I believe dictate open ended lugnuts with the threaded stud protruding thru the lug with at least a couple of threads showing.

Honestly, I know it must seem to be a pain in the rear but when you think about the physics of a 4000 lb car launching and the torque applied to the studs I would recommend some ARP wheel studs for your axles.

It means pulling the axle and pressing out the old studs and putting new ones in. It is a pain but....if you ordered some stronger than stock axles from Strange, Moser, or even Yokon you can order them with the studs already installed. 

Just my opinion and yes.......I've seen cars shear wheel studs at the track......and on the street. 

:cheers


----------



## Chris-Austria (Dec 23, 2010)

Okay good to know!
I already raced with my car and the Cragar SS wheels. I can tighten the lug nuts almost 7 full turns, so that would be 7/20" Engagement on the stud.. which seems to be not very good if I need at least 10/20". The steel wheels that I now ordered for the drag racing will make about 9.5-10 turns. So it's just as much as I really need.

I'll check how much turns can really be made, use open end lug nuts and if it isn't 10 turns I will get new studs. My rear is a 69 HD-Safe-T-Track, I think thats a BOP 8.2 without the C-Clips. Where can I find instructions to replace the studs by myself? Or should I go and visit a shop for this change?
Maybe I should add that the studs look new to me, probably they have been replaced in the past.. do the ARP have a logo or is there a way to identify if the studs are strong or not?


----------



## Chris-Austria (Dec 23, 2010)

I searched for wheel studs from ARP but I cannot find ones that I think will match my car.

What are the stock dimensions of the rear wheels studs of my 66 GTO? (the rear end is from a 69 Judge)

Rockauto sells 1.5" length studs with .472 knurl Diameter. Has the knurl to be exactly the same as stock? If so.. there are only 1,5" length studs available... 

I'm now worried about safety.. especially with the Cragars and only about 0.36" engagement. I tested my wheels again and the steel rim engages 0.52". So if the new steel rims with the drag tires will also engage 0.52" it should be fine I hope?!
I found an article that says I need 7/16" engagement if I have 7/16" studs, 1/2" if I have 1/2" studs and so on. If that is true I guess the steel racing rims are on the safe side, but the street Cragars still ain't.
But because the power with my Cragars isn't that hard as it will be with the drag tires (that won't spin at the starting line) maybe I can get away with only 0.36" engagement on these street tire rims?
I run the Cragars for at least 2 years and never had a problem. Also the lug nuts didn't come lose, I check them every few weeks anyway. 

Don't know what to think now.. I would buy some studs that are about 0.3 to 0.5" longer if I knew where to get them and what overall length is needed to achieve that.


----------



## ALKYGTO (Mar 29, 2010)

This is what you need. http://www.summitracing.com/parts/arp-100-7702/overview/


----------



## Chris-Austria (Dec 23, 2010)

Thank you. So the knurl diameter does not need to be exactly like before?
If my stock studs are 1.5" length and the ARP are 3.2"... I think this will look very strange for my street wheels (also the closed lug nuts won't fit).
Isn't there a choice that is only about max. 0.5" longer than stock? (I don't know stock length, but I guess it's 1.5")

edit:
I just found these.. 0.25" more than I probably have now: http://www.summitracing.com/int/parts/msr-8259/overview/
0.36+0.25 = 0.61" for the Cragars which seems to be enough and 0.52+0.25 = 0.77" for the drag wheels which should be enough as well. What do you think?
Will the studs I found fit and what about their quality? (I remember that I chose only ARP bolts for my engine)


----------

