C2 Rear Spring plate mounting Bolt finish

[Tim S.]

Are the four bolts for the C2 mounting plate to the differential zinc (cad) plated or natural phosphate in color.

Thank you

[Ed S.]

Re: C2 Rear Spring plate mounting Bolt finish

Tim,
First, when you say "mounting plate" I assume you are talking about the rectangular plate that goes under the spring, the one that holds the spring up against the bottom of the differential. If you are referring to those bolts I am quite sure they are black phosphorous,they are not zinc. That is true for a '64. Don't know if the finish is different for other mid years.

[Richard G.]

Re: C2 Rear Spring plate mounting Bolt finish

The 63 bolts are also

black phosphorous.
Be sure to complete the final bolt torqueing sequence after the car weight is on the spring.

[Russ S.]

Re: C2 Rear Spring plate mounting Bolt finish

Richard, I wouldn't call it the final bolt torquing sequence as that would tend to indicate that the bolts can be tightened down to nearly tight before setting the car weight on the spring when in reality the weight needs to be on the spring before the bolts are tightened to the point of final torquing. The weight should be set on the spring soon after the bolts start straightening the spring arc out.

The 63 bolts are also

black phosphorous.
Be sure to complete the final bolt torqueing sequence after the car weight is on the spring.

[Joe L.]

Re: C2 Rear Spring plate mounting Bolt finish

Are the four bolts for the C2 mounting plate to the differential zinc (cad) plated or natural phosphate in color.

Thank you

Tim------


The 63 to at least 1974 bolts were black phosphate.

Sometime after 1974 (1977 as I recall) the bolts changed to 7/16" from the 63-74 9/16". As I vaguely recall, the later 7/16" bolts might have been zinc plated. I can't check this at the moment as I'm in Italy.

[Edward J.]

Re: C2 Rear Spring plate mounting Bolt finish

Tim,
one other important part of the rear spring plate bolts are there length , There have been many rear housings plates cracked over the years, the after market or repro bolts are all to long, be sure to re-use your original bolts. (4 1/4" long).

[Ed S.]

Re: C2 Rear Spring plate mounting Bolt finish

So, my question is, when the bolts are initially run in with out the weight of the car on the spring - how tight should they be? I am in this situation right now. Car is up on stands, I have reinstalled the diff and complete rear suspension. Being aware of the DO NOT TIGHTEN issue (from this thread) I ran the bolts for the spring plate in by hand and then tightened them with a socket wrench up to the point where the lock washers were just about to begin closing - they were still "open" or in their natural non compressed state. At that point everything is snug and not able to move around. Plan is to tighten to specified torque values when the car is sitting on the ground. Is what I just described satisfactory?

[Stephen L.]

Re: C2 Rear Spring plate mounting Bolt finish

Ed, Your procedure to tighten after the weight is on the suspension is correct.... Just enough torque to keep things in place. Hang a note on the suspension to tighten later so you don't forget and drive the car....
The same procedure is applicable to all suspension pieces, bushings etc. Don't tighten until the car is on the ground......

[Russ S.]

Re: C2 Rear Spring plate mounting Bolt finish

Ed. Yes that would be good.

So, my question is, when the bolts are initially run in with out the weight of the car on the spring - how tight should they be? I am in this situation right now. Car is up on stands, I have reinstalled the diff and complete rear suspension. Being aware of the DO NOT TIGHTEN issue (from this thread) I ran the bolts for the spring plate in by hand and then tightened them with a socket wrench up to the point where the lock washers were just about to begin closing - they were still "open" or in their natural non compressed state. At that point everything is snug and not able to move around. Plan is to tighten to specified torque values when the car is sitting on the ground. Is what I just described satisfactory?