1973 YJ8 Aluminum Wheel lug nuts

[Edward M.]

I just discovered an interesting piece of information about the lug nuts that were planned to be used on the 1973 YJ8 Corvette Aluminum Wheel.

The part number for this lug nut is 329383. The part number for the 1976 and later YJ8 wheel lug nuts is 371674.

They are not interchangeable. The 1976 and later lug nuts will NOT fit into the openings on the 1973 YJ8 wheels.

Now for the big discovery...

The 1973 YJ8 wheel lug nut is the very same lug nut that was used on 1975 (and perhaps 1976) Cosworth Vegas with the Aluminum Wheels. Part number 329383. There are plenty of them available on Ebay and other places.

[James G.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

This lugnut has been well researched by myself as well as many other high end resto GM guys.

The correct 329383 lug nut with the TALL CROWN has not been available since the mid 70's, the replacement 414 short crown lug replaced the TALL CROWN 329383 in approx 1975.

This lug was used with the following cars which runs their value through the stratosphere... imagine you are competing for lug nuts with a guy who has a GSX, W30 Conv, 70 LS6 Chevelle conv, or even a 69 COPO Chevelle - believe me they are willing to pay 1200 for lug nuts.

1967-1973 Oldmobile SS1 and SSII's -
1967-1973 Buick open faced wheels including GSX
1969 1970 Chevelle and NOVA with spoked SS wheels
1969 Camaro SS with optional spoked wheels
1970-73 Z28 Camaro
1971-1972 Chevelle and elcamino SS
Cosworth Vega.

FWIW There were actually 2 different 414's lugs, the early one which was crimped on the second design was resistance welded to the nut. (pictured below) and is identifiable through the area above the flats which is welded to the top of the nut... the other design is not so flat across the top where the cover would contact the nut face.


The tall crown first design stainless capped lugs do not allow the lug wrench to cover the flats on the lug.
The lug nuts sell for approx 1000-1200 per set IF YOU CAN FIND THEM!
I have inquired about having the stainless covers reproduced from a deep draw stamping company and went as far as sending them the original drawings and blueprints.

[Edward M.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

Great info, many thanks.

Have you dissected one to see what it looks like under the stainless cover?

[James G.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

Yes, that is how I figured out that they later ones were resistance welded.

[Edward M.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

Got any pictures of them dissected. Just curious what they look like without the stainless steel cover.

I am sure I have a few of them laying around, but not sure which version they are. I have been dragging around a collection of old lug nuts, etc. for 30 plus years.

At that price I might have to go find them.

[James G.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

What does the seat of the original 73 YJ8 look like? Is the bevel Large?
If you will note the photo above the 383 cap extends down further and because the lugs wouldn't fully engage in the lug wrench the wheels didn't get tightened as much as they should have.
This causes the lug hole to wallow out
Then the lug nut seats deeper into the taper -
which causes the edge of the Stainless cover to get caught on the Larger wallowed out taper
eventually deforming the crimp on the cover,
ultimately causing the cover to come loose...
(the resistance welding to the top of the "updated" style forever eliminated that problem... YOU HAVE TO DESTROY THE COVER TO REMOVE IT and the top "crown" stays welded on the nut.)

FWIW The patent drawings show a modification in the early 70's which indicate cover attachment of a few different types and one was resistance welding, after tearing it apart and finding no signs of any epoxy or other adhesive I made an educated guess.

There was a shelby vendor reproducing a lug nut which is visually identical to the 383 (with the crown and lug flats of equal height)- however it is a 1/2" thread with if I am not mistaken a -13/16" nut . STEVE FULLER REPRODUCTIONS - they run $400 a set when he makes them. (I will tell you that if you had wallowed out lug holes a 1/2" stud would fix it and the lugs FULLER MAKES would pass judging as the difference between 3/4 and 13/16 visually is nearly undetectable.

[Joe L.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

a 1/2" stud would fix it and the lugs FULLER MAKES would pass judging as the difference between 3/4 and 13/16 visually is nearly undetectable.

James------

I'd say it would be pretty detectable with a 3/4" socket.

[James G.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

That would do it alright...

[Joe L.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

That would do it alright...

James-------


The things that these NCRS judges will do to "get to the truth"............! And now we have given them a new idea to add to their arsenal!

[Duke W.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

I just discovered an interesting piece of information about the lug nuts that were planned to be used on the 1973 YJ8 Corvette Aluminum Wheel.


The 1973 YJ8 wheel lug nut is the very same lug nut that was used on 1975 (and perhaps 1976) Cosworth Vegas with the Aluminum Wheels. Part number 329383. There are plenty of them available on Ebay and other places.

I believe lug nut for '76 Cosworth Vega is 371674 (Group 5.813, H Aluninum YJ8 N77), although the parts book is a little vague, and I'm pretty sure the '75 CV lug nut is different. IIRC the '75 CV nuts have some sort of center insert that is black. GMPD split the parts book in '76, and mine only covers '76 to '80 models, so I don't have any pre-'76 part numbers for Chevrolet models other than Corvette, which was a separate book.

Maybe 329483 is the '75 CV lug nut. If someone has the '75-prior pass. car (except Corvette) parts book maybe they can confirm.

The Z09 Cosworth Vega Special Performance Equipment Package was made up from many option codes, some of which were optional on other Vegas and some that were unique to the CV, including the aluminum wheels, although there are reports that CV wheels showed up on some Monzas in the late seventies because GM had an excess number in inventory. That was probably the N77 option. N77 is defined in the option section as: "Wheels 13x6/Alum. Hub Caps & Whl. Nuts"

Unfortunately some of my build sheet is missing including the RPO breakout prior to Q, and there is no YJ8 listed, but I expect the missing part would include N77.

Duke

[Duke W.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

Here's a photo of my '76 CV's LF wheel as it currently sits in The Petersen museum.

Duke

[Harmon C.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

The real 73 lug nut have the black center.The proof is at the National Corvette Museum on Zora Duntov's 74 with the 73 wheels. If you go their you can check out the 73 wheels and lug nuts. I bought 5 73 wheels at the auction at Bod McDorman's and the holes are smaller than 76 and newer wheels. The lug nuts are not tapered but are straight and fit down in the smaller hole. I was the only one that knew what they were at the auction. I have a few other 73 wheels I found one at a time.

[Duke W.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

So it sounds like the '75 CV lug nuts and the '73 Corvette YJ8 lug nuts are the same.

Duke

[Edward M.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

Yes, that is correct. And this lug nut was used on other cars as well.

[Joe L.]

Re: 1973 YJ8 Aluminum Wheel lug nuts

This lugnut has been well researched by myself as well as many other high end resto GM guys.

The correct 329383 lug nut with the TALL CROWN has not been available since the mid 70's, the replacement 414 short crown lug replaced the TALL CROWN 329383 in approx 1975.

This lug was used with the following cars which runs their value through the stratosphere... imagine you are competing for lug nuts with a guy who has a GSX, W30 Conv, 70 LS6 Chevelle conv, or even a 69 COPO Chevelle - believe me they are willing to pay 1200 for lug nuts.

1967-1973 Oldmobile SS1 and SSII's -
1967-1973 Buick open faced wheels including GSX
1969 1970 Chevelle and NOVA with spoked SS wheels
1969 Camaro SS with optional spoked wheels
1970-73 Z28 Camaro
1971-1972 Chevelle and elcamino SS
Cosworth Vega.

FWIW There were actually 2 different 414's lugs, the early one which was crimped on the second design was resistance welded to the nut. (pictured below) and is identifiable through the area above the flats which is welded to the top of the nut... the other design is not so flat across the top where the cover would contact the nut face.


The tall crown first design stainless capped lugs do not allow the lug wrench to cover the flats on the lug.
The lug nuts sell for approx 1000-1200 per set IF YOU CAN FIND THEM!
I have inquired about having the stainless covers reproduced from a deep draw stamping company and went as far as sending them the original drawings and blueprints.

James------


You and those other "high end GM resto guys" have got this largely incorrect.

Neither of these lug nuts is a GM #329383. The lug nuts shown are tapered seat type lug nuts; the 329383 was not a tapered seat lug nut. The 329383 was applicable to 74-75 Cosworth Vegas, 1975 Chevrolet Monzas with RPO N77, and 1973-75 Corvettes with aluminum wheel. The only other GM car line that used these nuts was Pontiac but I don't know what model(s). The 329383 was not discontinued in the 70's and replaced by the GM #414188. In the first place, the 2 nuts are absolutely NOT interchangeable due to the different seat type so the former could not possibly have been superseded by the latter. In the second place, the GM #329383 was available into the 1990's and was discontinued without supersession in 1994. Also, the 329383 does have a black insert on the face as others have noted.

The nut on the left of your photo looks like a GM #414188. I expect that the one on the right is a GM #399683. The 399683 was used on many Chevrolets (including 71-74 Vegas), Pontiacs and Oldsmobiles in the 1969-74 period. The GM #399683 was discontinued in July, 1974 and replaced by the GM #414188. The 414188 was used on most GM car lines. It was discontinued and replaced by the GM #12387947 which remains available from GM to this day.