C-3 leaf spring bolts

[Dan G.]

I'm restoring my 73 rear suspension and frame, I started to reassemble the original leaf spring with the 4 bolts that came in a suspension rebuild kit I purchased from a catalog, long story short I punched through diff. cover on the fwd right bolt with little effort when tightening the 9/16 bolt.
I measurered their bolts at 3 3/4 but my originals are 3 1/4, everything on my car is original and any way you measure it their bolts are 3/16 too long, I called them and they said that was the correct part # kit and length of bolts for my car. Anybody else added a new drain hole to their rear end with after market kits?

[Alan S.]

Re: C-3 leaf spring bolts

Hi Dan,
Sorry, I can only try to console you. I checked my 71, original cover and bolts... 3 1/4" long. Someone put the wrong bolts in the kit.
Are those bolts for an aftermarket 'heavy duty' cover?
Regards,
Alan

[Wayne M.]

Re: C-3 leaf spring bolts

....I measurered their bolts at 3 3/4 but my originals are 3 1/4,

Dan -- they gave you the wrong bolts. Here's the originals on C2's; measure 3_3/16" from under the head to the threaded end. Then, there's those thick lock washers, at least 1/8". As added protection, there's the limited # of threads, so you can't over-penetrate.

[Joe L.]

Re: C-3 leaf spring bolts

Dan -- they gave you the wrong bolts. Here's the originals on C2's; measure 3_3/16" from under the head to the threaded end. Then, there's those thick lock washers, at least 1/8". As added protection, there's the limited # of threads, so you can't over-penetrate.

Dan and Wayne-----


Yes, these are special bolts used for all 1963-77 Corvettes. They have a non-standard unthreaded shank-to-thread length. The longer unthreaded shank is designed to ensure that the threads do not contact the spring leaves. The threaded portion is, as Wayne points out, short enough that over-insertion is pretty much impossible. These bolts were GM #3833486, but they were discontinued years ago and replaced by GM #9428598. The latter bolt is a more-or-less standard bolt with a different unthreaded shank length and different thread length. It's also discontinued.

Paragon reproduces an outstanding reproduction of the 3833486 bolt. It is VERY important to use the correct bolts for the spring plate application (as Dan has found out the hard way).