55.2-59 Firewall Pad

[57FleetsideC4]

Hi All, On the 57 I am doing I am starting to weld in the holes in the firewall I don't need. There is a series of 3/8" holes that look like for the firewall pad I am guessing. The question is do most use some sort of Fat Mat/Dynamat type material in that area or the stock firewall pad? I was thinking of laying down fat mat throughout the whole cab to quiet it down. Thanks Steve

[mr48chev]

Many of us make so many changes on the inside of the firewall (along with the outside) that a stock style firewall pad gets cut up a lot if you use one. AC/ firewall mounted pedals, --------- and what not.

[1project2many]

Different products have different jobs. Materials such as Jute are used to reduce certain frequencies of sound. Fat-Mat is for different frequency. It generally takes a combination of both to make the cab quiet.

I made my own pad using jute with foil glued to linoleum. The jute has aluminum foil on one side. The other side is glued to the linoleum. The linoleum is reversed so the "bottom" faces the interior of the cab. It is painted flat black. I feel the combination of heavy, dense linoleum plus jute plus aluminum is very effective at keeping noise and heat out of the truck.

For the floor I used the same jute material under a repro rubber floor mat. It also keeps heat and noise out. I used spray on undercoat inside the doors. They are quiet although Fat-mat might be a better choice.

The inside of the truck has been quiet for years. I believe the door seals, installed in '97 or '98, are losing flexibility because I now hear wind noise that I never heard before.

My work truck is a new body style '07 GMC. It had minimal noise reduction. I suffer from tinnitus caused by wind noise so quieting that truck was very important. For the work truck I installed jute and asphalt on the floor and the rear of the cab under the factory rubber mat. That truck seems noisy still although better overall. Again, I believe fat-mat in the doors could help.

[mr48chev]

1project2many hit on an important point. How quiet do you need it or how much heat transfer do you want to block.

I'm another one with tinnitus and prolonged exposure to noise doesn't help. Plus being in my mid 70's I want the interior more comfortable and quieter than I did when I bought the truck when I was 28 and the noise and heat didn't bother me so much and sealing the doors and air leaks was more about keeping winter cold out.

I'm looking at lining the inside of the cab and roof with Lizard skin and then going with fatmat over that.

[57FleetsideC4]

Thanks everyone for the suggestions and things to think about. This truck is far from stock and am just welding up unnecessary holes in the firewall now. I forgot about the lizard skin and may be the way to go with fat mat over that. I just want the truck fairly quiet inside without building up a lot of material on the inside. Steve

[57FleetsideC4]

So I am getting ready to weld up the holes that held the original firewall pad in place and am guessing most don't use that pad. The only reason I am on the fence is this cab will go to sandblast soon and don't want to fill the holes then realize I probably shouldn't have later. I would think going with the lizard skin sound deadener and the fat mat over that would be as good as the factory style firewall pad. I used fat mat on the wagon that I did and it went down nice but only used it on the floors and wheelhouse and wonder how it would stick to the firewall with no retainers. Steve