1968 Pontiac Firebird Sound Control Work

Well it started out pretty simple. I had some rust spots to fix in the lower corners of the front foot wells. In the
process of doing that I removed all the old asphalt sound deadener pads. They looked like they were still the
originals from 40 years ago and stunk like they were, even if they were not. The old carpet also stunk like
something 40 years old. Once I had the rust fixed in all areas of the floor and cleaned up the inside of the door
panels I coated everything with the Chassis Saver Urethane coating. I coated the inside of the doors and the
bottom channel area with rubberized undercoating. I used brush-on where I could get the brush into and aerosol
where it was tight. Making sure the drain holes in the door stayed clear. I then started looking at replacing the
sound deadener mats. I did a bunch of research on the internet and learned a lot about sound deadeners from
the "Ricer" sites and great review sites like "http://www.sounddeadenershowdown.com/" There I learned about
the pros and cons of modern sound deadener like Damplifier Pro. I chose this mostly based on the customer
reviews I read online and the results of the showdown site. I found a supplier in Alberta through a bunch of
emailing. Allan Rod and Custom in Calgary were great to deal with and the partsman Zane set me up with 3 boxes
of the stuff and 2 rolls of Overkill for good measure. I used the overkill closed cell foam on the doors, rear quarter,
wheelwell area and under the dash over the Damplifier (this is the thinner black foam you see in the pics. I
purchased a roll of "Hot Rod Insulation" from Allan Rod to use over the Damplifier mats on the floor boards. It
looks a lot like regular carpet underlay but with a foil layer that goes on the bottom side for extra heat reflection.
You can see the Hot Rod insulation in the pictures as the grey stuff. I also used a closed cell foam I had for the
places in the trunk and interior to fill in all gaps between the overkill and the hot rod insulation. It is the white stuff.
I purchased an OER firewall pad from Ames . The insulation layer underneath looked just like the hot rod insulation
and the top layer was like a black neoprene rubber. It was die cut to fit on the firewall perfectly. Actually it was a
good fit but "perfect" may be a little strong. I bought the cheaper firewall pad and not the "formed" one as I
thought it was a little too expensive for what it was.

You can see in the pictures below that this turned into quite an adventure and took several months of work to complete.

the floor inside coated with Chassis saver.

the rear seat area of the interior with same.

this is a shot of the box top of the sound deadener mats I chose.

and away we go... here is a shot of the front half done. I used a little rubber roller I had to roll
down the mats. The stuff cuts pretty easily with a razor knife but you have to be very careful
as you are working with it. The foil layer is like a razor blade and if you slide unprotected fingers
along any edges before it is properly rubbed down you will end up with lots of hand cuts. By the
time I was done the whole thing my hands looked like I had wrestled seven cats for a chicken bone.

drivers footwell and firewall "damped".

rear section done.

firewall area done all the way up and under the dash. should be rattle free. and if there is ever a
Nuclear war, we can hide in the car. It looks bomb proof :-)

closer up under dash.

even closer under dash.

rear shot showing thru to trunk. all damped. for full trunk story, see that page.

did inside door panel and outside. My doors close with a solid thunk like a caddy now.
This is a shot to show the door holes still open.

close up inside door.

for all the door holes large than a half-inch, I cut out 18 gauge aluminum plates and applied
Damplifier to the back of the patch. Each plate was then screwed over it's corresponding hole
with little #4x1/2"RH sheet metal screws.

here you see the pass door with all of its cover plates attached. I did the front doors and the
rear seat 1/4 panel area as well.

and the drivers door with its plates all attached. applying the old stock style paper water sheilds
at this point whould have been silly so they were left out.

then the overkill was applied over the filled door. 3M # 77 was used to adhere the foam.

rear quarter area with dampened patches on.

then overkill applied to that area and the wheel well. some of the stereo cables done later on
can also be seen in this picture.


view of both door and quarter areas and the floor with underlay application started.

view of the firewall pad. it is held in place with mainly spray on adhesive. 3M 77 was used.
I did not use the supplied plastic push thru fasteners as i did not want them poking thru into
the firwall area and as you will see later I closed almost all the old firewall holes.

another view of the firwall pad installed and you can see the rest of the trans tunnel insulation applied.

view under dash of overkill glued on. there is some red dash paint overspray on the silver mats at
this point because I did the interior painting before the insulation foam went in. you can see the
fresh dash paint in several shots like below.

here you can see what I did in the kick panel area. I inserted/adhered pieces of the hot rod
insulation in the two openings in the speaker area. The holes where the fresh air vents are was
brushed/sprayed liberally with rubberized undercoating.

front area all insulated.

rear area all insulated.

And that is about it for sound deadening. i think I should have a pretty squeak,
resonance, and rattle-free interior.

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