Cabin Sound Deadening

[Slugfarm]

My daughter's dog doesn't like riding in my 65 Valiant, and my wife absolutely refuses to, mostly because it just gets too loud at speed. Rumbling tires, engine noise (4bbl Slant 225 with solid lifters and Dynaflo muffler), and wind noise through all the gaps in the doors and body all contribute. What strategies and techniques have folks found successful in quieting the cabin?

 

[67Dart273]

1...Rear mount small resonator and tailpipe out the rear
2...Floor insulation if not, does not take much and add some to the rear cavities such as quarter windows area and behind seat/ trunk bulkhead. Fiberglass weighs little
3..."Gaps?" "Gaps?" I don't understand. Holes in the body/ weatherstrip/ etc will suck in exhaust if nothing else.

One of these girls in good shape should not be substantially noiser than a typical modern car

 

[MinnesotaMopar]

If I was a smart___s, I would tell you to swap the engine with an electric motor. But... I won't do that.

From my own experience even the best sound insulated car will become loud inside with a loud exhaust. So the exhaust will be the best place to work to solve the problem. You need a quieter OEM type muffler, and an exhaust pipe that exits at the rear bumper. Of course that takes a lot of fun out of the car, but that is the sacrifice we have to make to please our non-motorhead family members.

You can put in dynamat type insulation on the floor and behind the interior panels but that is only a very small help for a lot of work and expense. If you haven't already done so, sealing off the trunk from the passenger compartment will make a lot of difference. And don't forget to close off and insulate the opening behind the back seat, since a LOT of noise will come through the seat itself.

There is little to be done with the wind noise, since these 50 year old cars were just are not very aerodynamic and have lots of places on the body the wind will whistle over, such as the rain gutters. You can get new door and window gasket rubber and make sure the doors are adjusted to close tightly and that will help, but only a little. You could test this by temporary putting duct tape on all the gaps and then going out for a drive to see if the improvement is worth the effort. Sound insulation on the bottom of the hood can be a significant help since a lot of sound will come in through the cowl vent. You could try taping off the cowl as well to test that.

Good luck and be sure to let us know if the dog approves of your changes. Inquiring minds want to know.

 

[Lord Sparky]

Without full-framed doors, the wind will always get in. Even with new weatherstripping, it’s difficult to perfectly adjust the windows.

 

[dart4forte]

I just turn my hearing aids down

 

[Slugfarm]

I just turn my hearing aids down

My strategy has been turning the stereo up but that really pisses off the dog.

 

[Slugfarm]

3..."Gaps?" "Gaps?" I don't understand. Holes in the body/ weatherstrip/ etc will suck in exhaust if nothing else.

The body's is good shape, but the driver's door is a little rough, and there's just so much new weatherstripping and seals seem to do. Definitely need to replace the wing vent seals though.

 

[LO23M8B]

I just put the top down.

 

[Just Send It]

This is the stuff that I used in my 72' Scamp. 60ft was enough to cover the entire floor, inside of the firewall, inside of both door panels, and inside of both quarter window areas. I even had some leftover. The downside is it's pretty heavy. If you don't mind the extra weight, it's hard to beat. Very easy to install as long as you have a roller.

With the windows up, I can have a nice conversation with my passengers. My 421 stroker is loud and the exhaust dumps right in-front of the axle.

 

[Sdriche]

Kilmat

 

[RustyRatRod]

I used Kilmat in Vixen. Covered the floors, trunk floor and roof. It rides really quiet. Kitty loves it. She's proud mainly because she helped. lol

 

[leechris81]

Another vote for Kilmat. $60 from Slamazon and covered the entire floor pan of my ‘73 Swinger. Noticeable difference in road noise. Good for temp control too.

 

[Mineallmine]

X3 on the Kilmat. I put it in my 63 Dart and when I have it running (stock 170 slant with a slightly louder muffler) it is very quiet inside. This is sitting in my garage running with the door closed and just a hose under the door for exhaust. I would imagine it'll be even quieter once I get it outside in the open. I haven't had it out for a drive yet (hopefully in the next week or two it'll be done) to test for road noise. I even put it on the inner roof before installing the headliner. Took out the tinny sound when you tap the roof. Nice thump sound now. If you go sound deadening make sure to go right up under the rear seat. This is a common spot for a lot of noise as that's commonly where the muffler sits

 

[Jim Kueneman]

I know your pain. I have found that the early A bodies seems to be the worst. I thought the '63 Dart was noisy because it was a convertible but the '66 Valiant is noisy as well. The aerodynamics are terrible. If there is not much wind then it is not bad but if it is a windy day just the exterior wind noise gets old. I have new weatherstrip and everything this adjusted correctly and there is no air leaks, they are just noisy cars and push a lot of wind. My '68 Coronet is much better quieter but the Duster is the best of the bunch. Seems like they finally started thinking about how the car moves through the air with that body style.

 

[Slugfarm]

Thanks all. Ordered the Kilmat and should see it arrive Monday. On another note, anyone have hints on successfully removing a headliner? I still have shoulder belt straps waiting for me to figure out how to get the headliner out, and now I have extra incentive.

 

[LO23M8B]

Talk about noise, you should ride in my Caravan.

 

[Slugfarm]

My wife's CR-V isn't exactly peaceful, either. There's only so much one can do to make a brick aerodynamic.

 

[Jim Lusk]

Noise? Bah. I've driven my son's 440/4sp Dart convertible 600 miles in a weekend. It's a visceral experience, all of it. These cars are meant to be heard and then some.