<VV> Bolt Grades

[Chris & Bill Strickland]

From: lonzovair at aol.com

>... as for the original bolts, I'm almost positive they have a round head like a carriage bolt, but without the square "wedge" under the head... The originals I took off my 64 were like that, and the NOS ones I got from the east coast vendor were just like them...
>

Fig 3-5 in the 64 Shop Manual shows a hex headed bolt, and the Feb 72 P&A 30C pg 7-5 P also shows a hex headed bolt, which is not described in Sec 7.529 except as 2 req'd "rear spring to control arm" & "Bolt Unit consist of 1 bolt, 2 washers, 1 nut, 1 pin."

Which makes it sound like GM #3876804 is not just a bolt, but a "Bolt Unit" all in one package.  Did your NOS ones come this way, and which style bolt was it that broke, Lonzo?

I do recall buying a pair of these new from GM in the 70's, but don't remember anything about them except I installed them when I added the 64 style rear suspension to my 1st 60 4-dr in the early seventies cause the used bolts were pretty beat up.  

I would not be using a carriage head style bolt for this application unless it is specifically specified as not a Grade 1 bolt, which most carriage bolts are.  Perhaps, if it is this style bolt that's failing, they are incorrect, regardless of origin -- Lonzo wrote, "I was about 40 miles from home when the bolt snapped" and "The originals I took off my 64 were like that, and the NOS ones I got from the east coast vendor were just like them..." -- Tom wrote, "MIne broke by failure of the threaded connection between the nut and bolt" and that he overnighted two new replacements from Clarks.

I no longer have a 64 Assembly Manual to check there.

Bill Strickland