1966 lower A-arm to frame bolt @ rear: GM 3779097 vs GM 3795792
Gary
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Gary -
Re: 1966 lower A-arm to frame bolt @ rear: GM 3779097 vs GM 3795792
From a 1962 Corvair parts book:IMG_0224.jpg -
Re: 1966 lower A-arm to frame bolt @ rear: GM 3779097 vs GM 3795792
Gary,
Great find. Thanks!
GaryComment
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Re: 1966 lower A-arm to frame bolt @ rear: GM 3779097 vs GM 3795792
Gary,
Did you find that bolt via an internet search? If so, how did you do it? I thought I was pretty good at internet searches, but Icame up blank.
GaryComment
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Re: 1966 lower A-arm to frame bolt @ rear: GM 3779097 vs GM 3795792
The question of these bolts illustrates an interesting point. The ‘63 thru ‘65 AIMs call for bolt GM 3779097, with a special serrated washer under the bolt head, then on the other end a lock washer and a thick nut, that some call a hi-nut. The ‘66 AIM calls for a different bolt, GM 3795752, plus the special serrated washer, then on the other end a locking nut, GM 9422304. Of course the use of a locking nut meant a lock washer was no longer needed. And that probably precipitated the change in bolt, which did not have to be as long given the absence of the lock washer. A shorter bolt = cheaper bolt.
The question I had about that bolt is, when did that change happen? Or more accurately, should my car have the later bolt and lock nut? Unfortunately, the revision date in the ‘66 AIM for the change to the new bolt can’t be definitively determined because it was one of the first 8 revisions in the ‘66 AIM, the documentation of which disappeared when the revision block filled up and revision number 9 appeared at the top of the revision block. John Hinckley has stated that revision 9 was dated 8/30/65, so the prior 8 revisions must have happened no later than 8/30/65. Which means the charge to the locking nut and bolt GM 3795752 was meant to happen at the start of the ‘66 model year. But similar to my ‘66, which was built the last week of the ‘66 model year, other ‘66 owners have stated in the archives that their ‘66 cars, including some late build date cars, have the ‘65 bolt and the lock washer and hi-nut, and not the locking nut. Which suggests that the change in bolt and nut that was meant to happen at the start of the ‘66 model year according to the ‘66 AIM, did not happen at all during the ‘66 model year. The use of the ‘65 bolt, lock washer and hi-nut is consistent with the description in the ‘66 JG, so it appears the ‘66 JG Revision team found no convincing examples of the use of the later style bolt and locking nut.
The year-long use of the ‘65 bolt, lock washer and nut through the entire ‘66 model year could be explained if GM had a large inventory of those items, and continued to used those fasteners until the inventory was used up. That is a practice that has been previously speculated about a number of parts and fasteners. For the fasteners in question, that would mean an inventory of more than 55,000 of each fastener, based on two each per car in 1966. Maybe the new bolt and locking nut was used at the start of the ‘67 model year? That’s a research project for someone else to conduct.
GaryComment
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