'66 nut

[Richard S.]

Afternoon gents....This may be a stupid question, so be it if it is. Cleaning up a few parts on my '66 and on page 271 of the AIM the nut holding the lower A-arm stop and spacer does not use a lock washer, is there anything special about that nut 103025, possibly a locking nut? Thanks for any reply.
Ric

[David L.]

Re: '66 nut

Ric,
First of all never use the page number. Page 271 in my 1966 Corvette AIM is the "REAR BUMPER". Use the UPC # and Sheet #.
I can not find bolt # 103025 in my 1966 on UPC 3, Sheets A2, and A3. I find bolt # 103028 that attaches to the top of the ball joint on the lower A-frame.
Dave

[Richard S.]

Re: '66 nut

Sorry, did not realize AIMs were different, so would the correct identification be UPC-60 sheet B4? Thanks for the help.
Ric

[David L.]

Re: '66 nut

No "UPC-60" in my 1966 AIM. Is "UPC-60" a typo?

[Richard S.]

Re: '66 nut

Wow really screwing this up aren't I, maybe UPC-c60 might work better. This is a '66BB A/C car, the stop on the lower A-arm has a spacer under and the AIM shows no washers of any description, thought the lower nut securing said parts should have a lock washer or a locking nut, hope this helps. Thanks for your patients.

[Gary B.]

nut part number 103025

[Richard S.]

Re: '66 nut

Boy am I glad we are on the same page now, was getting ready to sell the old girl and move into an assisted living complex. The bolt has plenty of thread to put a lock washer, different bolt used as compared to non A/C cars, maybe GM wanted to save money. Anyway thanks Dave and Gary for the help, no washer it is.

[Gary B.]

[Page C.]

Re: '66 nut

This appears to be a regular 5/16 x 24 tread nut with a plain finish in the GM Engineering Standards that secures the rubber bumper to the lower "A" arm. There is no lock washer shown in the UPC C60 B4 section of the 1966 AMI. Also as a side note to some recent post as to the direction of the bolt thru the bumper and "A"arm. All show the bolts going thru the bumper, a spacer (in this case), the "A" arm with the nut on the bottom.

[Gary B.]

[David L.]

Re: '66 nut

Ric,
The 3742252 bumper assembly is attached with a 3784302 bolt (5/16"-18 X 3/4" with attached non-removable lock washer and 5/16"-18 nut (286M , 17/64 " thickness, plain finish according to my 1978 GM Standard Parts) as shown on UPC 3, Sheet A3. Therefore, an additional lock washer is not required.
The same 3742252 bumper assembly is attached with the 3894561 spacer as shown on UPC C60, Sheet B4, and therefore needs a longer bolt, GM # 274423.
As stated by Gary, the 274423 bolt has fine threads, 5/16"-24.....I assume that it is longer than 3/4" (effective length).

Does your 274423 bolt have an attached non-removable lock washer? The nut, GM # 103025, is 5/16"-24 as mentioned by Gary.
GM # 103025 is not listed in my 1978 GM Standard Parts catalog.

It appears to me that the 3894561 Spacer was only used on the 1966 Corvette with 427 engine and A.C. as per my vintage parts catalogs and 1967 Corvette AIM.

Dave

[Gary B.]

[Richard S.]

Re: '66 nut

In regards to the bolts currently securing the stop and plate my bolts are 1 1/4in in length 5/16-18 had lock washers used in conjunction with the nuts and went from top to bottom. I have only owned this car since the early '80s so who knows what transpired prior to my ownership. Are these head markings indicative of a line used bolt?IMG_2016.jpgIMG_2018.jpg

[Gary B.]

[Richard S.]

Re: '66 nut

Gary,

Interesting that the P head could be original, when I removed them they required a little work (soaking) to remove without destroying so appeared to be original, but one never knows what transpired before my ownership. The spacer measures 1/2in hence the extra length for these bolts.

Ric