Bruce Schug wrote the following about using 3rd generation Camaro IROC-Z wheels on his Corvair:
My experience is with the 16" x 8" IROC Z-28 wheels. I'm sure the 15" wheels are the same.
Yes, the studs are different. The Camaro uses metric studs which take a different thread. So you can't use the Camaro lug nuts. You have a couple of choices. You probably could install the Camaro studs into the Corvair hubs, which would allow you to use the Camaro lug nuts. I think I heard of someone doing this. I don't know what the situation is with the different diameter of the Camaro studs which are metric. I don't feel this is a very practical solution.
Secondly, you can keep your Corvair studs. This is where the real problem arises. The Corvair lug nuts WON'T pull through the wheel, this is a pretty severe exaggeration of the problem. The problem is the angle of the surface which the lug nut contacts is different and the Corvair lug nuts won't fit properly. This is not a life and death situation. I ran Corvair nuts for awhile until I understood and solved the problem. The Corvair nuts just chew the mating surface up a little each time they're installed. The solution is to get different lug nuts which have the standard Chevy threads, but with the angle to fit the Camaro Wheels.
I found an article in the July, 1988 Hot Rod which reads as follows:
"One of the new trends in street chic wheels is the use of late-model IROC Camaro and Corvette wheels on early-model Chevys. While the 4 3/4 inch bolt pattern remains the same, the specific late-model metric lug nuts cannot be retained. Some rodders are using incorrect acorn-style lug nuts and other designs that do not offer the proper contact area for the radiused contact face - and could be dangerous. However, Ronal Wheels (15692 Compuer Ln., Huntington Beach, CA 92649, 800/552-0934) offers a lug nut for its R9 wheel (part No. 2160) with the standard 7/16 x 20 thread for early Chevys that works perfectly."
I purchased 16 of these from a Super Shops speed shop. They aren't cheap, at the time they were $3.50 apiece, but they are good. I then found a set of wheel locks which fit the Corvair studs. These don't have the proper angle, so I always use them in the same hole. This way they don't ream out all the holes, just that one.
I understand there is another nut which is supposed to work. It's called a Gorilla "bulge" nut. I think Gorilla is the brand name. Bill Pritchard used to have some of these. He's in the Roster. These were less expensive than the Ronal nuts. (NOTE: Gorilla PN 41177 is a 7/16-20 thread nut with 3/4" drive hex).
Another issue you should give some thought to is the length of the stud. Because of the increased wheel thickness, you have fewer threads which the nut screws onto. I just measured that my rear nuts are on 5 1/2 threads, the fronts 7 1/2. I guess the wheels are a little different thickness. How much do you need? I think I remember NHRA requiring threads equal to the diameter of the stud. A 7/16" stud would then require 8.75 threads, more than I have. Longer studs are available. Someone gave me a GM part # 3910340, which is a Corvette stud which is 1/2" longer. I use stock studs and have never had a problem. My use has included spinning my car a few times, once on the street, the rest at autocrosses, with 225/50-16 Gatorbacks. If you decide to use longer studs, be sure your lug nuts have enough depth to accept them.
Bruce W. Schug
Ron Blachut noted that the GM stud above has been discontinued, he used Dorman 610-186 Lug Bolts which are 1 1/2 inches long and are available in decent auto parts stores.
Seth Emerson also posted the following on lug nuts:
At a recent trip to the tire store, I noticed that McGard, the company known for their locking lugs for wheel-theft protection, makes a standard (non-lock)"bulge-style" lug nut in a 7/16 RH thread. This thread is the size to fit our Corvairs. These nuts are needed when aluminum wheels from newer cars, for instance the 82-92 Camaro, are used on our Corvair's non-metric wheel lugs. The drive hex is still the same size as stock. The bulge-style nut has an exaggerated cone at the contact point between the lug nut and the wheel. This cone keeps the tips of the lug nut hexagon from digging into the wheel cone when you tighten down the nuts. The McGard number is P/N 64011 (this P/N gives you a set of four nuts, buy five sets to get your 20 lugs for your late model!) You can go to the McGard site for more info.
Here's another possible source I got from a classic Olds owner over the net:
Company name: WESTESCO
Address: 800 S. Vail Ave, Montebello, Ca. 90640-5418
Phone: 323 685-6464
Just tell them you're looking for a 7/16 bulge style lug nut.
This one from Spence Shepard:
From Tony Irani:
Mr. Lugnut part# 5352-4. Four for $6 at my local speed shop. They may have a package of 5 #5352-5.
7/16" Open Bulge should work on any aluminum wheel.
I had an online chat with the Dorman Rep. which also sells lug nuts. Their part # 711-105
Is identical to Gorilla PN 41177, suggested by Bruce Shug. It's readily available at Oreiley's auto parts, $5.99 for a set of 4
I did a little measuring and found the stock studs are just under 1 1/2" length under the head, which means the Dorman 610-186 studs are very close to the stock studs. For a little more length with aluminum wheels, use the Dorman 610-259, same knurl, but are 1 3/4" long. This is the Dorman replacement for the Corvette studs mentioned elsewhere. If you want longer still, perhaps for a disc brake conversion, Dorman 610-157 is 2 1/8". The knurl is a bit bigger at .487" vs. the stock .472", but I am told they pull in ok.
If you do need to swap the studs, Seth Emerson wrote this about how to do it:
I have just popped them out with a hammer. Never a problem. The replacement stud installation depends on the length. I just installed the 3" ones available from Moroso onto my 65. (The Moroso studs have a nice lead diameter before the threads.) The front install was easy. Insert the stud, stack greased washers over it, invert a normal lug nut and impact/pull the sucker in. On the rear, the hole in the flange was decidedly smaller than the front. You couldn't tell visually, but the same studs were much harder to pull into place than on the front hubs. The problem you may find on the rear is finding enough clearance behind the flange to get the long stud into the hole in back of the flange. I was converting to disks, so I had no brake backing plate interference, and it was still tight around the bearing casting. If you are just going to the 1.75" long Corvette studs, this shouldn't be a problem.
- Seth Emerson
Roger Gault offered this for getting them in (assumes no trouble getting them started):
If you've removed them all, just start all 5 of them back in enough to be pretty stable. Then you can put the drum back on and lock the brakes to stop the rotation while you wrench them the rest of the way in. Four feet of pipe slipped over the breaker bar will be worth the price of the pipe.