NHRA regulations about wheel studs.

[Blmpkn]

Is anyone here knowledgeable? @Maritime Drag Racing perhaps?

Building my caprice to more or less be a drag car. It's going to be fast enough to need a cage, so I'm curious as to what all I need to comply with for rear wheel studs? I know there ARE regulations concerning them.. but there just seems to be a TON of conflicting information on the internet so hoping someone has some recent first hand knowledge on the subject.

A ford 9" axle will be on its way to me relatively soon from Moser.. want to make sure I pick the right options on the build sheet.

Thank you!

 

[Snoranger]

Last time I looked into it was when I worked in my buddies chassis shop. Back then the rule was...
If your running slicks, you must use open ended lug nuts and the stud must stick out by AT LEAST the diameter of the stud.
So 7/16” studs must stick out at least 7/16” from the end of the lugnut.

 

[Blmpkn]

Cool. I don't think I'm going to run slicks.. but we'll see.

It just occurred to me that I could and should probably download the rule book from the nhra website what a dummy lol.

 

[Shran]

I'm curious what their logic is there. Seems like flush with the nut surface would be sufficient? It'll never break off past the nut... wonder if it's just some arbitrary formula they picked to make it easy? Kinda like 8x170mm bolt pattern is stronger than 8x6.5"?

 

[Snoranger]

I'm curious what their logic is there. Seems like flush with the nut surface would be sufficient? It'll never break off past the nut... wonder if it's just some arbitrary formula they picked to make it easy? Kinda like 8x170mm bolt pattern is stronger than 8x6.5"?

Yes, flush would be fine, until the nut loosens up a little... then it’s got less thread engagement. I sure wouldn’t want to lose a wheel at 150mph. I wouldn’t even want a loose wheel, but it’s better than no wheel.

 

[Shran]

That makes sense.

 

[Roert42]

It’s also makes it a lot easier to quickly tell if your studs are long enough.


Why wouldn’t you run slicks if it’s going to be primarily a strip car?

Plenty of room to store them while driving on the road.

 

[don4331]

Last time I looked into it was when I worked in my buddies chassis shop. Back then the rule was...
If your running slicks, you must use open ended lug nuts and the stud must stick out by AT LEAST the diameter of the stud.
So 7/16” studs must stick out at least 7/16” from the end of the lugnut.

They don't need to stick out 7/16", they need 7/16" engagement

Now, having them long enough to extend past the nut is a good idea. From my engineering: A minimum of two thread pitches should extend beyond the top surface of the nut. Where practicable, the number of threads protruding should not exceed five. In no case should thread protrusion exceed ten threads.

To require a cage, you need to be running in the 10s (i.e. 10.99 or quicker) or over 135 mph. I know there are now drag radials that are probably good for that, but wouldn't slicks make it easier?

 

[ITSA 7]

If I remember correctly , you need to be running in the 9s to require a cage. A roll bar is good to 10.0s. Open lug nuts are require so the tech inspectors can check the length of the stud without removing the lugnut.

 

[ITSA 7]

Dong Racing???-Google it.

 

[Blmpkn]

Slicks WOULD make my goals easier.. but although I'm setting it up to be a strip car it's gonna see more time on the street and I don't want to get ticketed for bald/non DOT tires lol.

Perhaps when the car is "done" I'll spend the money on another set of wheels/tires to swap back and forth.. probably wouldn't happen until '23 though.