I have frequently heard people, including many 'Vette owners, say that C3's "sound like a bucket of bolts" when driven on rough roads. To some extent I agree, but I have never been content to live with noises that shouldn't be there. It makes it worse that my rainy day car is a Lincoln Mark VIII, which rides more quiet than the average driver, so there is a bigger contrast when switching to the 'Vette (my '80). So I am a bit obsessive when it comes to hunting down and eliminating those annoying rattles. This is what I have found so far (not all have been fixed yet).

First, the obvious:
- Spare tire carrier had no spare, what a racket! (Carrier has been removed)
- Door glass on both sides is loose (my next project)
- The rear compartment doors were trashed, all the tabs that grab the hinge rods were broken and the doors just bounced around (new RCU installed with new carpet)
- No jack in rear compartment, but the spring was there
- The dash speaker covers are not snug, just laying on top

The less obvious:
- The front right fender bond has broken in the wheel well (future project)
- A couple screws were missing in the plastic cover under rear window
- The battery clamps were not installed, but were found loose under the battery
- The taillights are all loose, but I cannot tighten the screws any further (future project)

I found several more subtle sources when I pulled and replaced the carpet:
- The plastic bracket on the left rear speaker was cracked and rattled against the speaker
- The right rear speaker bracket bolts were half-way unscrewed, allowing the speaker to rattle from road noise and too much bass.
- Behind the left rear speaker, the small bracket that secures the body mount nut had broken loose. The nut is secured by the bolt that comes up from underneath, but the bracket was loose on top of the nut
- There was a surprising amount of debris under the seats, in the pocket under the carpet that held the seat belt retractors on earlier years: broken glass (probably from the original glass tops), a beer bottle cap, a few small bolts, some loose change, a factory rivet, and a one inch polished rock

I added about 60 square feet of Dynamat Extreme under the carpet, around the speakers, and in the rear compartment, which has gone a long way toward a quiet ride. Door glass is next, then the taillights. Any recommendations for loose taillights? And what other sources of rattles have you found?

 

While you have the doors apart put Dynamat on the outer door skin and also on the surface of the inner door behind the door panel.

 

i know what you are going through as i have addressed some of the same issues with rattles and finally have a quiet car,ya right.anyway just a tip to those with door rattles,i added a rubber isolator on the lower connecting rod of the door release mechanism.my car already had one on the upper vertical rod.slid on the shaft about half way just enough to contact the door frame.worked wonders.i wonder if mine were just missing or was never in gm's plan.(it is not installed yet in this photo).