Bumper nuts: �67 vs. earlier C2

[Michael H.]

Re: Bumper nuts: When the changeover?

Micheal,

That seems to be the case; maybe 4 months or more of '66 inventory.

Gary

Thanks Gary. I learned something.

[Richard M.]

[Gary B.]

A few months ago I removed these from the rear frame-to-bumper brackets from '67 vin #041xx, built Nov 17, 1966. They are 5/8" ATF nuts.

Rich

Rich,

Your bumper nuts are consistent with what is expected for a '67 made in Nov.

Those two broken bumper bolts in your first photo bring back vivid memories of removing many of the bumper bolts on my '66.

Gary

[Ronald L.]

[Ray G.]

While you guys are pondering the difference from 66 to 67 in these bumper nuts, has anyone noted the difference in the plate washers for these?

In 1965 the washer was 120395
1966 was 9419276

Anyone know what the difference is?

Hello Ron;
Does that sound/look like a updating part number change to cover more than one application?
Ray

[Joe L.]

While you guys are pondering the difference from 66 to 67 in these bumper nuts, has anyone noted the difference in the plate washers for these?

In 1965 the washer was 120395
1966 was 9419276

Anyone know what the difference is?

Ron-----


GM #120395 had a 15//32" hole, 15/16" OD, 1/16" thick and was zinc plated.

I have no specs of GM #9419276.

[Ronald L.]

[Scott S.]

While you guys are pondering the difference from 66 to 67 in these bumper nuts, has anyone noted the difference in the plate washers for these?

In 1965 the washer was 120395
1966 was 9419276

Anyone know what the difference is?

Ron,

GM 120395 is a 15/32" ID x 59/64" OD x 5/64" thick steel flat washer, Group 8.929

GM 9419276 is not so easy to find. The ones I had reasonable cause to think were original measured 1/2” ID x 7/8” OD x 1/16” thick.


Edit: I just saw Joe's post, the info I found for the 120395 was in the Gr. 8.929 section of the 67P&A. The '70 SPC shows the same, but catalogs from other years (older or newer) sometimes show small variances, I don't know why.

[Ronald L.]

[Gary B.]

Washers for bumper bolts

While you guys are pondering the difference from 66 to 67 in these bumper nuts, has anyone noted the difference in the plate washers for these?

In 1965 the washer was 120395
1966 was 9419276

Anyone know what the difference is?

Ron,

Was the 9419276 washer continued thru the 1967 model year or further?

Gary

[Gene M.]

[Gary B.]

My very early 67 #440 had 5/8" nuts in the rear. I remember that very clearly since just about everyone was snap using a breaker bar and impact.

The fronts I'm not clear on since they unscrewed and were not eventful. But they were all rusty and went in the trash.

As a standard today the 5/8" nuts with 7/16" thread are not stocked as are the 11/16" nuts. The 7/16" thread is a bastard size hardware compared to all the rest that have common head and nut size.

Gene,

Thanks for the info on your '67. I'll add it to my growing database of responses for '67 cars. To date, it appears to me that the 5/8" across the flats (ATF) nuts continued to be used into Dec of '66 and perhaps periodically into Jan of '67, at which time the 11/16" ATF nuts started appearing more consistently. It's true that the 5/8" ATF nuts are hard to find, but the 11/16" ATF nut in the correct black phosphate are not trivial to find either. The 11/16" AFT nuts that one can easily find in your local hardware store are zinc, or that gold-ish color if grade 8.

Gary

[Ridge K.]

[Scott S.]

[Scott S.]