Lug nuts

[gp02a0083]

Hey guys , getting my 86 cutty ready for some passes down at Englishtown NJ. I have set aside a pair of tires mounted on aluminum rims. They do fit the bolt pattern on the 7.5 rear (im assuming the studs are of the stock type, in the past 11 years ive had the car they never needed to be changed)

my question is for the g-body guru's out there, whats the pitch and thread for the rear lug nuts, i have to get the type that looks like a hat with a lip, the aluminum rims i have are flat. They do not have the kind of recess that the original rims have.

 

[khan0165]

I believe pre-83, they used 7/16-20 RH studs. And after they used 12x1.5mm RH metric studs. However, in my experience most cars used 12x1.5mm RH metric. They are far more commonly available aftermarket as well.

original wheels used a conical seat style lugnut

and I'm guessing you need a shank style lugnut

shank style are common on aftermarket drag wheels, like Centerline rims. You will need to measure the shank thickness of your wheel, and order a shank lugnut with according length.
http://shop.mcgard.com/installation-removal

if you're in the market to change your studs, I recommend using extended studs. You may at that point need to use a openended lugnut. I recommend ARP studs.

 

[GhettoRacingKid]

do you have extended studs on there? bring your stockers just incase. could be a problem at tech.

 

[gp02a0083]

Khan, the rims i have look exactly like this :

My cutty is an 86 so i think im just gonna buy a set and return it if its not the right pitch.

 

[khan0165]

yeah, those look like they will need shank style lugnuts. So here's what you need to measure...

you need to measure the shank diameter, shank length, and you need to know your thread pitch. Please do not attempt to measure with a tape measure... get yourself a cheap digital vernier caliper, or micrometer. You will need to be a few decimals accurate.

Measure the diameter of the holes in the wheels, and the thickness of them as well. You will need to chose a lugnut which has a shank diameter as tight as possible, and a shank length that is long enough to grab most of the stud threads, but not bottom out on the hub before clamping the wheel down.

as an example...
I measured my Center Line Wheels. I was using a 7/16-20 RH stud, the shank diameter I measured to 0.715 inch, and the shank length at 1.410 inch.

so the closest lugnut with those dimensions had a 0.680 inch shank diameter, and 1.335 inch shank length.

this insured a tight fit within each wheel hole, without bottoming out the lugnuts on the hub. Notice how the diameter leaves a 0.035 inch tolerance? You want a very tight fit.

I was worried the length would be very tight and may bottom out, at 0.075 inch tolerance, so I used thick washers.

 

[gp02a0083]

i have to get the real picts of my rims/ tires later tonight so that im sure that they need a shank type lug nut. I have a digital caliper i can use to measure it so that shouldn't be a problem. I assume that i will need the shank type being my fatehr said i couldn't use the lugs i currently have on the car for the stock olds SS1/SS2's rims.

i suppose this isn't something i can go to autozone or pepboys and pickup a set?

 

[khan0165]

there are essentially 3 types of lugnuts...
1. Standard flat seat nut... very dangerous, avoid at all costs
2. Conical seat nut... most commong, very safe to use
3. Shank seat nut... common on alot of aftermarket rims, moderately safe

do not try using one lugnut for another type of application... If you have conical lugnuts, do not try using them if your wheels require a shank style.

yes, shank lugnuts should be available at any parts store. If they don't have them in stock, look up a part number from Summitracing or Jegs, and have them order it. Or you can order them yourself.

Summit is good for showing you all measurements you need, and that's how I got part numbers for my lugnuts.

 

[gp02a0083]

thats good to know that summit has that available. Thanks again Khan for your help, im probally gonna go by the ppart store before the end of the week. Like i mentioned i want to get some base line #'s for my cutty before i replace the rear end and a few other things.

 

[gp02a0083]

ok so i measured the rim this weekend. The studs i have on the car are 1.25 in long by 1/2" for the thread ( well according to the book at pep-boys lol)

i placed the rim on the lugs, used the conical lugs just to hold the rim up there. I measures 0.9-0.92" depth to the drum and about 0.7" diameter for the lug holes on the rim.

i think these would be the correct ones?

http://www.summitracing.com/parts/CRR-27723-4/?rtype=10

 

[khan0165]

I would recommend using these
http://www.summitracing.com/parts/CRR-27780-4/

essentially the same as you listed, but with round centered washers. The ones you listed have offset washers.