1967 Rear Suspension Bolt Finish

[Rob Matthes]

I am ready to start assembling my rear suspension. However, I keep getting conflicting information on the finish of the bolts. Are all the bolts cad/zinc finished except the cam bolt(s), spring lower mounting plate bolts, and the 2 long outboard spring bolts? I believe these should be black phosphate. Am I correct?


Thanks, Rob NCRS 29972 1967 327/350 hp

[Chuck G.]

Re: 1967 Rear Suspension Bolt Finish

The camber cam assemblies are cad/zinc. I've occasionally seen "gold tone" nuts used. The 4 center spring bolts are also cad/zinc, as are the 2 long bolts that go through the ends of the spring. I've never seen black phosphate in those locations. Others may disagree. Hope this helps. Chuck

[Shane G.]

Re: 1967 Rear Suspension Bolt Finish

My 64 NCRS judging manual says "..linked to the rear of the trailing arm with an assembly consisting of a black phosphate bolt, rubber cushions,bare steel retainers(washers),a "castle nut" and cotter pin. I am certainly not trying to say that the previous post was incorrect, but it is inconsistent with my manual. I am beginning to think that the manual may be doing me more harm than good since it has been inconsistent with the parts I remove from my (very beat up) very original car three or four times. From now on I will be much more careful purchasing "correct" components to replace the "wrong" ones I take off the car. BTW my Judging manual is about 5 years old now- Would it be a good idea to get a new copy, or will it have the same info in it?

[Rob Matthes]

Re: 1967 Rear Suspension Bolt Finish

My judging manual states the same for my "67". However, I still get different answers from the different "parts" suppliers. I am currently using "Winter 1997" manual. Is there an updated version? Has any of this type of info changed?


Rob

[Gene M.]

Re: 1967 Rear Suspension Bolt Finish

Rob, I think you are finding slight differences in the hardware finishes is due to various suppliers to GM and time periods. Let's take the outer spring bolt made by supplier with head marking "SBC" these bolts on my 65 were a grayish color, not black and not silver. Other suppliers may have used black oxide which lasts about 6 weeks then rusts appearing as never been plated. A clue as to original finish can sometimes be hidden under the rubber cushion. One thing else I can share, the trail arm cam bolts were all black finish (black oxide or black phosphate or maybe even black zinc), but rear cam plate was natural or had slight traces of dull cad. The nut was extra long and appeared the same as the cam plate. This is from many observations.

[Kent Lowry]

Re: 1967 Rear Suspension Bolt Finish

I believe the bolt you are asking about is P/N 3831585, if so, the GM Engineering Standards manual says it is a 9/16-18 x 6 3/8" Regular Hex head Grade 8 Black Phosphate bolt.