Trans Am Sound Insulation

Riding in Splendiferous Quietude

Deluxe sound insulation (BS1) was standard on Esprits and a common option on Trans Ams in the late 70's. It's not a very exciting option, but some reproduction parts can be ordered with or without sound insulation, which is a little bit confusing.

Standard Insulation

Firebirds and Trans Ams came standard with sound insulation in five areas:
  • Floor
  • Rear inner wheel housings
  • Seat belt reels (not shown)
  • Trunk (not shown)
  • Firewall (not shown)
  • Rear package shelf (not shown)
Hood insulation was really for heat, not sound, and some Firebirds had it depending on the hood type. Shaker-equipped Trans Ams did not have hood insulation. Turbo Trans Ams have elaborate hood insulation, and a radiation shield also, but they will still blister a hood bird off before any of the other decals crack.

High temperature insulation

All late 70's Trans Ams have mineral wool insulation in the area shown. This was just aft of the catalytic converter. Cars with N10 dual exhaust had it on both sides.

This would have been all white originally.

Floor Insulation

All late 70's Firebirds featured this type of sound insulation in the floor. It's a sandwich of soft waste fibers with brown tar paper on top. The piece shown out of the car is different. It's a solid piece of asphalt that goes under the driver's seat. I have tried to think of engineering reasons why it would be different, but I haven't come up with any.

This material came with all kinds of optional punchouts for floor-mounted items. In the upper photo you can make out the big square area that would have been removed for a 4-speed car.

Deluxe Insulation

Deluxe sound insulation added insulation to the B-pillars, area under the back seat, divider between the passengers and the trunk, and the rear package shelf. It also included a sound absorbing baffle above the driver's feet. Most of these items are illustrated here.

Rear Compartment Insulation

The top photo shows a car with deluxe sound insulation as it might appear when the rear panels are removed. The insulation on the wheel housing is standard. Optional items in the top view include:

  • B-pillar insulation panel in front of the wheel house
  • Trunk divider insulation
  • Additional under rear seat insulation. Particularly note the yellow pad laying on the hump.
Both of the black items are very heavy tar paper with a fiber mat underneath.

With the B-pillar insulation panel removed, you can just barely see that some holes in the metal body panel have been plugged with patches. These patches are like sheets of rubber covered with hot bubble gum. If you've ever had bubble gum drool out from under you rear interior panels in a Trans Am or Camaro, this is what causes it.

Deluxe Quietude Baffle

This panel mounts above the driver's feet, and you can see where the clutch and brake pedals would stick through. It is covered on the upper side with a sound-absorbing fiber mat. The two holes were used to screw it to the A/C ductwork. I'm not sure what it hooks to if you don't have A/C, but I'll have to figure it out, as one of our project cars is made that way. The rear corners mount to the gas pedal bracket on the right and a bracket added to the fuse box on the left. These brackets are shown below. The left bracket is for the early (up to 79) fuse box, and the right bracket is for the 80-81 blade fuse box. If you buy one of these baffles on eBay you might want to ask for the bracket or fab your own.

You'd think nobody would order deluxe sound insulation with a 4-speed and no A/C, but we've had two such cars. I always picture a person ordering the car saying "I don't won't air conditioning. No sir. It's too heavy and gets in the way when I want to change my plugs. I want to drag race. I'm going to put 4.11 gears in it. This car is going to be a hot rod. I always drive with my windows down anyway". Then the salesman says, "How about an extra 40 pounds of tar paper for a quiet luxury ride?" and the buyer says, "Sure, that'll be swell."

Available Reproductions

Shown below is the reproduction sound deadener, available anywhere, compared with the original material on the right. It's not made of simiar material at all, but it does a fair job of duplicating the shapes. Old insulation from the driver's and rear floorboards is not shown because it fell apart. That is pretty typical.
On the left a reproduction trunk divider baffle is shown installed in my car. These are very stiff when they are new and I had a hard time getting it to conform to the car. I made two long cuts in the bottom that can be seen here. Go back up and look at the old divider panel. There are some wierd bumps in the underlying steel, and they get tightly conformed over time.

This piece is very heavy and backed with a fiber mat, and it appears to be a very faithful reproduction. The standard sound insulation included a light brown paper divider and these are also being reproduced.

Our junk car Schultz has the optional quietude, but instead of the correct insulated divider it had three (3) standard dividers. I guess they ran out that day.

When I restored my interior I used some of the original sound insulation that was in good condition. Under the rear seat I simulated the original sound insulation by putting reproduction sound deadener over an original fiber mat.

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