undercoating inside the doors and sound deadener

[burdar]

So, my 68 Dart has factory undercoating inside the doors.(on the inside of the outer skin) There are no impact beams or anything inside the doors...they are just a hollow shell. Did the factory add an impact beam inside the doors at some point? What year? If/when an impact beam was added, did they omit the undercoating in the door?

I'm in the process of applying butyl sound deadening to the car. The floor is done and I'm to the point of doing the doors. Most of the threads I've read, people say to apply the sound deadener to the inside of the doors. They don't say anything about undercoating being there already. I'm questioning whether or not I need to add it to the doors if there is undercoating there since it's a sound deadener in itself. Then there's the fact that I'm not sure how well the sound deadener would stick to the rough texture of the undercoating.

Maybe the later years have an impact beam and no undercoating...thus the need to apply sound deadener in those cars? Thanks

 

[Treblig]

I always use brush-on liquid undercoat inside the doors to keep them from rusting. But be sure to leave the drain holes open at the bottom. The stuff I use is expensive but sticks to anything and won't come off. It goes on real thin not like bed liner, it also acts like a deadener. Dynapro 544 paintable rubberized undercoating.

 

[burdar]

There is already factory spray-on undercoat inside the doors. I'm using the foil backed butyl(Fatmat/Noico/Kilmat) type sound deadener on the floor and was going to use it inside the doors. Now I'm questioning whether it's needed in the doors since there is already undercoating there.

 

[Treblig]

There is already factory spray-on undercoat inside the doors. I'm using the foil backed butyl(Fatmat/Noico/Kilmat) type sound deadener on the floor and was going to use it inside the doors. Now I'm questioning whether it's needed in the doors since there is already undercoating there.

Most older cars I've done usually have old dried out undercoating there but the factory undercoat almost always doesn't cover the very bottom of the door. That's why doors always rust at the bottom, plus the drain holes get plugged. Clean the doors out real good and see if there's undercoat at the bottom of the doors!

 

[Murray]

Reinforcing beams didn't become standard until the '70's when safety became more of an issue.

 

[burdar]

So, did they undercoat the inside of the doors when the beams showed up?

 

[forphorty]

My 73 RR has intrusion beams and the factory undercoating in the doors. The undercoating doesn't extend to the bottom of the skin. A few of my own personal opinions: I hate that stick on sound deadener stuff. If you ever want to remove it, it's a royal pain in the azz. With the factory undercoating intact, I doubt there would be any audible resonance from the door skins unless you have a megawatt sound system. On the inside of my Duster quarters, I scraped off the old gooey factory undercoating and , after priming, applied a paintable aerosol chip guard . 3m Rocker Schutz works good but requires an applicator gun. For rustproofing in the door seams, I like 3m cavity wax. A lot of old undercoating will crack and separate from the body, allowing moisture underneath. It seems like the biggest noise issues with the old cars is wind noise. An otherwise super quiet car can make those little whistles even more annoying.

 

[67dodgedartconv]

I put fatmat in the inside of the doors over the factory undercoat on my 69 Barracuda. Haven't driven it yet but I can tell you there was a big difference to me in how the doors sounded when they closed. Much more solid sounding.

 

[str12-340]

no internal braces until they changed the doors and eliminated the vent windows (1973?). They changed all the internal mechanisms, moved the inside door release, redesigned the door interior appearance, so except for the outer skin they are really different - and weighed A LOT more.

 

[burdar]

I heard from some other people that they installed the sound deadener over the factory undercoat. I have (4) sheets left so I'll put three sheets in the doors and call it good. Once the glass is in and all adjusted, I'll put the last sheet on the inner door skin. That's got a lot of noise to it when you tap on it. I think that might be worth it more then the outer skin. Thanks

 

[Treblig]

I heard from some other people that they installed the sound deadener over the factory undercoat. I have (4) sheets left so I'll put three sheets in the doors and call it good. Once the glass is in and all adjusted, I'll put the last sheet on the inner door skin. That's got a lot of noise to it when you tap on it. I think that might be worth it more then the outer skin. Thanks

What about the bottom of the door where the rust usually begins? The lower door seams are really a problem because the seam holds moisture. I paint all those areas with the undercoat stuff I talked about earlier. The sound deadener would soak into the seams the way that liquid undercoat does.

 

[Mike69cuda]

I put the Dynamat right behind the door panels on mine & that seems to work well.

 

[burdar]

What about the bottom of the door where the rust usually begins? The lower door seams are really a problem because the seam holds moisture. I paint all those areas with the undercoat stuff I talked about earlier. The sound deadener would soak into the seams the way that liquid undercoat does.

The car just got painted. The bottom of the doors didn't need any work. They were perfect. The inside of the doors were completely sprayed with primer.(epoxy I assume) The drains are free and clear. The sound deadener is for "sound"...not rust protection.