66 Upper "A" arm nuts

[Edward S.]

The judging manual shows photo's and talks about the "tall" nuts securing the "A" arm but does not say anything about the finish of the lock washer or the nut. As I understand the original nuts are 7/16" tall, but are they cadmium plated which they appear to be in the photo's, or are they black phosphate? A member has told me the nut and lock washer on his car are black. What was original for my Dec. 65 build big block 66? Thanks for any replys. Ed

[Ron G.]

Re: 66 Upper "A" arm nuts

Edward,

The hardware to secure the cross shafts to the A-Arms has a natural finish and is not plated. This includes the nut and the lock washer. Unlike 1970-72's the nut is not a locking type and does not have the silver cadmium plating that the early seventies possesses. There has been a lot of controversy over this and anyone fortunate enough to own a true 63-69 Bowtie/Survivior will know this.

- Ron

[Joe L.]

Re: 66 Upper "A" arm nuts

The judging manual shows photo's and talks about the "tall" nuts securing the "A" arm but does not say anything about the finish of the lock washer or the nut. As I understand the original nuts are 7/16" tall, but are they cadmium plated which they appear to be in the photo's, or are they black phosphate? A member has told me the nut and lock washer on his car are black. What was original for my Dec. 65 build big block 66? Thanks for any replys. Ed

Edward------


GM says that the upper a-arm retaining nut used for 1966-67 was GM #9422300. This was a 7/16-20 stover-type lock-nut and it was zinc or cadmium finished. It was used without a lock-washer. I don't know if this is what was used for 1966-67, or not. It's possible that the earlier style standard hex nut with lock washer was used. If so, it should have been a GM #3722853 nut with a GM #103328 lock washer. The GM #3722853 was a 7/16-20 standard hex nut with a cadmium or zinc finish. I don't know what the finish was for the 103328 lock washer.

[Joe L.]

Re: 66 Upper "A" arm nuts

Edward,

The hardware to secure the cross shafts to the A-Arms has a natural finish and is not plated. This includes the nut and the lock washer. Unlike 1970-72's the nut is not a locking type and does not have the silver cadmium plating that the early seventies possesses. There has been a lot of controversy over this and anyone fortunate enough to own a true 63-69 Bowtie/Survivior will know this.


- Ron

Ron-----


1963-67 used a nut with 7/16-20 thread. 1968-82 used 7/16-14 thread. So, with respect to the upper control arm retaining bolts and nuts there was no commonality between C2 and C3.

GM says that all 1968-82 Corvettes used nut GM #9422299. This is a 7/16-14 stover-type lock-nut and it's zinc or cadmium finished. The original nuts on my 1969 are exactly this configuration and finish. Also, I have numerous NOS examples of the 9422299 and all are as described.

[Tony S.]

Re: 66 Upper "A" arm nuts

Joe, I agree regarding the '67 using a lock nut. There is no purpose to be served by using a lock washer with a lock nut. My '65 uses a lock washer and a tall nut. The change over must have occurred in '66.

[Scott S.]

Re: 66 Upper "A" arm nuts

Edward,

The hardware to secure the cross shafts to the A-Arms has a natural finish and is not plated. This includes the nut and the lock washer. Unlike 1970-72's the nut is not a locking type and does not have the silver cadmium plating that the early seventies possesses. There has been a lot of controversy over this and anyone fortunate enough to own a true 63-69 Bowtie/Survivior will know this.

- Ron

Ron,

I see why there is controversy, is this a case where the AIMs show one thing, but on the Assembly Line, the AIM was not followed in practice?

The AIMs call out the following:

1963 AIM: GM 3722853 Nut, with 186418 Lock Washer
1964 AIM: GM 3722853 Nut, with 103328 Lock Washer
1965 AIM: GM 3722853 Nut, with 103328 Lock Washer
GM parts books show that 3722853 is a 7/16-20 regular hex nut

1966 AIM: GM 9422300 Nut, with no Lock Washer
1967 AIM: GM 9422300 Nut, with no Lock Washer
GM parts books show that 9422300 is a 7/16-20 distorted thread locking-type hex nut. The 1966 & 1967 Judging Guides are in conflict with each other: 66JG shows photo of tall hex nut & lock washer, 67JG describes cad or zinc locking nut.

1968 AIM: GM 9422299 Nut, with no Lock Washer
1969 AIM: GM 9422299 Nut, with no Lock Washer
GM parts books show that 9422299 is a 7/16-14 distorted thread locking-type hex nut


So, what is correct for 1966-1967? The only GM photo I can find showing the upper control arm cross-shaft nuts is in Adams p. 359, the photo of the 1966 L-79 being lowered onto the frame. It looks like it might be a tall nut, but it’s hard to be sure.

[Timothy B.]

Re: 66 Upper "A" arm nuts

I can attest for sure the attaching nuts on my September 1966 built 67 car has stover locking nuts at the location described.

I always thought the earlier cars had tall nuts with lock washers but it's interesting the description from GM calls out a standard nut at this location. Does standard nut make reference to the height or just the thread without locking.

[Michael H.]

Re: 66 Upper "A" arm nuts

I can attest for sure the attaching nuts on my September 1966 built 67 car has stover locking nuts at the location described.

I always thought the earlier cars had tall nuts with lock washers but it's interesting the description from GM calls out a standard nut at this location. Does standard nut make reference to the height or just the thread without locking.

Timothy,

You were right the first time. The nut for all 63 through early 66 was a tall hex nut, used with lock washer. I think it was plated a grey plating of some sort. At some point in 66, the nut was changed to the zincad plated stover/self locking design without lock washer.

[Scott S.]

Re: 66 Upper "A" arm nuts

I can attest for sure the attaching nuts on my September 1966 built 67 car has stover locking nuts at the location described.

I always thought the earlier cars had tall nuts with lock washers but it's interesting the description from GM calls out a standard nut at this location. Does standard nut make reference to the height or just the thread without locking.

Tim,

In this case, the GM parts books did not reference height or thickness. The GM 3722853 is listed in several different Groups, including the Standard Parts section, under the heading "8.915 Hexagon Nuts (Cadmium Plated)", and shows a drawing of what I called a "regular" Hex nut, as opposed to the next heading "8.916 Check Nuts (Lock Nuts) (Jam Nuts) (Cadmium Plated)", etc. My use of the term "regular" only meant without the locking feature.

Another GM book with Standard Parts section lists GM 3722853 under the heading "8.915 Nut, Common Hexagon — (Cadmium Plated)"

It seems that fairly often the finish called for in the parts books is not the same as the finish on the parts actually used in Production.

[Gary B.]

Re: 66 Upper "A" arm nuts

Timothy,

You were right the first time. The nut for all 63 through early 66 was a tall hex nut, used with lock washer. I think it was plated a grey plating of some sort. At some point in 66, the nut was changed to the zincad plated stover/self locking design without lock washer.

Michael,

When you says that the change to the Stover nut was made "At some point in '66", do you mean in calendar year '66? I ask because my July 20 build date '66 had the tall nuts with the lock washer. Not the Stover-type nut. I have no reason to think those nuts on my car are not original to the car, which suggests the tall nuts & lock washer arrangement was used throughout the '66 model year.

Gary

[Michael H.]

Re: 66 Upper "A" arm nuts

Michael,

When you says that the change to the Stover nut was made "At some point in '66", do you mean in calendar year '66? I ask because my July 20 build date '66 had the tall nuts with the lock washer. Not the Stover-type nut. I have no reason to think those nuts on my car are not original to the car, which suggests the tall nuts & lock washer arrangement was used throughout the '66 model year.

Gary

Gary,

I probably shouldn't have said early as I really don't remember/know when the change occurred in 66 production. I only know that during the early part of 66 production, the tall nuts and L/washers were used and at some point, were replaced with the locking style nut without L/washer.

Could have been around the same time that the control arm shaft was changed from the rectangular design to the rounded design??

[Ron G.]

Re: 66 Upper "A" arm nuts

To All My Corvette Buddies Above,

Now how did I know that this thread would be loaded with replies by the time I came home this afternoon. All I can say is that evey single mid year that I have looked at never had the 70-72 locking nut and maybe like Scott mentioned that maybe some how the AIM is in correct. I respect everyone's knowledge on this discussion board and I know better to never say never, but I never seen them on a midyear that was virgin to human hands. However, we all know that it is common to replace the first configuration with the latter version. Go head hit me up. That is the purpose of this discussion board is for us to discuss and feed off of each other. I am now leaving for the gym, and by the time I come back, I will expect some more action on this.

- Ron

[Tony S.]

Re: 66 Upper "A" arm nuts

I'm pretty sure '67's used locking nuts.

[Matt L.]

Re: 66 Upper "A" arm nuts

66 vette, misc 328.jpg

i hope this helps. this is from my very original 66 built mid april.

take care,
matt

[Ron G.]

Re: 66 Upper "A" arm nuts

If the photo from Matt Lewis's car is the original hardware than that is what I have been saying all along. That is a tall nut with locking washer with no plating on it, just raw steel. Again I rest my case.

- Ron