Bumper nuts: �67 vs. earlier C2

[Gary B.]

[Ray G.]

[Gary B.]

In my meager opinion this also applies to the black phosphate fasteners.

Ray,

But the NOS example I have of GM# 9418897 is 11/16" ATF, not 5/8". And the bolt heads are still 5/8" in '67.

Gary

[Joe L.]

Gary------


The GM #9418897 nuts on my 1969 are 11/16" across-the-flats and are phosphate-finished.

[John M.]

[Gary B.]

...I have never seen anything but the 5/8 nuts used everywhere else...

John,

Does your statement apply to '67 as well? If so, that would be inconsistent with the '67 AIM. That issue is partly what I'm trying to determine.

Gary

[John M.]

[Michael H.]

[Gary B.]

...The change, if it ever actually did occur in 67, may have been late production and if, so, I don't know why the change.

I could believe it happened late in the '67 model year, since it appears the change was in place for the '68 model year.

But why no revision date in the '67 AIM?

Gary

[Gary B.]

Yes all 1963 to 1967, I have been around some 67s in the last 25 or so years, I have never seen a 1967 without the 11/16 nuts..........Thanks John

John,

I'm confused. You say you never saw a '67 without the 11/16" nuts. Or did you mean to say you never say one with the 11/16 nuts?

Gary

[Michael H.]

I could believe it happened late in the '67 model year, since it appears the change was in place for the '68 model year.

But why no revision date in the '67 AIM?

Gary

The revision to the 11/16" hex nut for all locations was scheduled for "start of production" of 67 but most likely didn't occur that way. A likely reason would be found on a NPC (notice of production change) issued some time prior to 67 SOP.

When parts are changed, the NPC will show instructions for the "disposition of existing stock". (the 5/8" hex nuts)
If a part is installed the same as the previous part, and requires no change in assembly procedure, the change may not actually occur in production for weeks or months until the stock of the replaced part is exhausted.
If the new part is not installed the same as the previous part, the existing stock will be "used elsewhere" or returned to GMAD.
Some parts are immediately sent to "scrap".

In the case of the nut hex size change, it would definitely not be "mix with existing stock" because that would cause problems on the assembly line if "some" of the nuts were 5/8" and "others" were 11/16'. The installer would have to use two different size drivers to install the two different size nuts and that would be confusing and time consuming.

For cases where there is a safety issue, or there was some serious difficulty installing the part on the assy line, the change may occur immediately.

The dates in the AIM's should not be used as the actual time the change occured in production.

[Gerard F.]

I could believe it happened late in the '67 model year, since it appears the change was in place for the '68 model year.

But why no revision date in the '67 AIM?

Gary

Gary,

Got your email message and I will check the "nuts on my 67" bumpers tomorrow.

But looking at my 67 AIM, the date of the drawing (UPC-14. A2) is 5-9-66 with a REL. of 6-13. I assume that the REL. is a release date.

That may explain why there is no revision date for the nut indicated in the AIM. Looks like the AIM page was redrawn for 67 production.

[Gary B.]

Gary,

Got your email message and I will check the "nuts on my 67" bumpers tomorrow.

But looking at my 67 AIM, the date of the drawing (UPC-14. A2) is 5-9-66 with a REL. of 6-13. I assume that the REL. is a release date.

That may explain why there is no revision date for the nut indicated in the AIM. Looks like the AIM page was redrawn for 67 production.

Jerry,

So are you saying if a change was made between model years there would be no revision date, but just a release date?

Gary

[Gerard F.]

[Gary B.]