Forgot how loud these cars are, how to quite it down

[oldford]

I would like to insulate the interior of car to help with noise. There are so many products to choose from. Anyone recommend a good insulator material.

[JayJay]

Originally Posted by oldford

I would like to insulate the interior of car to help with noise. There are so many products to choose from. Anyone recommend a good insulator material.

Just went through this. Noise and heat needed to be reduced to satisfy my navigator. I have some background in industrial noise reduction, the principles are the same: reduce noise production (not much you can do in a Model A), radiation (dampen panels) and transmission (insulation).

Dynamat brand seems to have the most vocal proponents as a dampener and insulator, but it is quite expensive. Almost any of the two-component (rubber and metal) stuff sold in sheets will work fine, and there is some European stuff available. I used nominal 2 mm when I did the kick panels on my ‘31, but I think next time I would use thicker stuff. Look on the River Store for “car acoustic insulation”. I found that adding in an AcoustiShield firewall insulator (quietride.com) really helped with noise, as did filling the openings at the base of the cowl with foam backer rod. I also put two layers of 1/8” foil/foam thermal insulation on top of the acoustic insulation. Next time I would go straight to 1/4” or thicker.

To cut down noise transmission, look to put the rubber on large panels - cowl, door, floor pans. Doesn’t have to be 100% coverage, just enough to break the vibration. Quietride sells kits of insulation plus their firewall insulator. The metal panels act sort of like speakers transmitting vibration noise unless properly damped by the firmly attached rubber. Warning - you really need to put a lot of pressure on the rubber to get it to properly and effectively attach to the metal panel. I use a wallpaper seam roller.

But be realistic - you’ll never have it as quiet as a modern car. If that’s your goal, buy a Lexus.

[German guy]

LOL! I never had a pre-war classic before and was amazed at how noisy my 30 A was when I bought it. Here is what I did:


Removed all interior panels and applied two component sound/thermal adhesive insulation...the kind with one side black sticky asphalt stuff and a metalic waffle side...to EVERY surface (controls vibration resonance),...inside door panels, firewall, every floor board...both sides. Then I added a Dynamat version(egg carton looking) foam inside door and wall panels. I did the same thing under the hood and on the fuel tank on the engine side.


TaDA! I can actually hold a quiet conversation in the car. The only part that is visible is under the hood...buy as long as I do not fold it over...just use the hood support rod it is barely visible.

[chap52]

I always left my hearing aids at home. Chap

[Dan McEachern]

Snyders sells a firewall insulator panel. That and insulation on the floorboards- either under the mat or under the floorboards will eliminate a good majority of the engine noise. It will still be a Model A when you get done, but .......

[nkaminar]

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I just turn my hearing aids off. If you don't wear hearing aids use ear plugs or you soon will.

[Y-Blockhead]

First I spent a lot of time tracing and eliminating all the squeeks and rattles I could find. Then I used Dynamat in the body, doors and cowl area. The doors sound really solid now when you shut them. Firewall has a QuiteRide Firewall Insulator. Under the carpet and seats, I used Dynamat and foil backed insulation. Foam Backer Rod helps with heat and under hood odors entering the cab from the lower cowl area.

I have a roll of DynaPad that I have not installed yet.

[LeonardS]

B-QUIET.COM I am not associated with them, but I have purchased their noise and heat reducing products. Excellent quality at a fair price. Check them out.

[Synchro909]

How soft have we become to be complaining about a little noise and heat. Heck our cars are light years ahead of the horses they were replacing so IMO, we have nothing to complain about.

[CT Jack]

There are 2 basic types of annoying Model A noise. A constant drumming sound and rattles. The rattles seem to lessen when driving on smooth surface roads. Rattling can be somewhat reduced by tightening, strapping, or sealing. It is also important that the exhaust manifold an muffler connections are sealed. The drumming or constant vibrating noises can be reduced by applying sound dampening materials and sealing as indicated in the posts. I installed sound dampening material behind all panels. It is important to seal the edges of the floor boards and tighten them to the frame. I used 1/2" thick felt carpet padding material over the floor boards and fastened them with double faced velcro. Then I installed carpeting over the felt. When cruising at 55mph on fairly smooth roads the level of the drumming sound is present but not as loud as it would be if I had rubber mating over the floor boards. If your engine has a vibration problem or the Ujoint is worn there's not much that can be done other than drive drive slow.

[Y-Blockhead]

No complaining here, but it doesn't hurt anything to make your ride more comfortable by adding a little insulation.

[oldford]

Lots of good info to think about. Sold a vintage V8 car and thought I would get a car that was not as loud. I was wrong. How can a 4 cylinder car be louder than a V8. Thanks everyone for your input.

[Synchro909]

Originally Posted by oldford

Lots of good info to think about. Sold a vintage V8 car and thought I would get a car that was not as loud. I was wrong. How can a 4 cylinder car be louder than a V8. Thanks everyone for your input.

Our house was never so noisy as when we had little people in it.

[JayJay]

Originally Posted by Synchro909

Our house was never so noisy as when we had little people in it.

Yeah, same here - but never as much fun, either. Like driving a Model A. Infinitely more fun than whatever comes on second.

[Zax40]

Does anyone know of a Dynamat type product that doesn't have a logo or graphics all over it?

[LeonardS]

Originally Posted by Zax40

Does anyone know of a Dynamat type product that doesn't have a logo or graphics all over it?

None on the B-quiet material that I received.

[serocontra]

would any of these tips be useful on an open car?

[David in San Antonio]

@Serocontra - I installed the single piece firewall insulator (Snyder’s) and it helped a bit. Then put this stuff: https://www.designengineering.com/fl...esive-42-x-48/
Under the floorboards, dimpled metal side down, including the removable metal covers for battery access, etc. Also on the underside of a muffler heat shield-deflector https://www.snydersantiqueauto.com/p...8527&cat=41736
Installing the muffler heat shield did NOT take 10 minutes.
For the floorboards I traced them onto brown paper, cut out the paper stencils, then laid the paper onto the insulation and traced the outline using a Sharpie.
Cutting the darn stuff was interesting. A regular heavy duty scissors cut the reflective dimpled metal sheet, but the attached fiber insulating material jammed the scissors, and the very aggressive adhesive layer and peel-off plastic stopped all progress. I tried a few other things then finally: plunge a sharp utility knife vertically through the whole sandwich to make a puncture. (Put corrugated cardboard underneath so you can punch through the sandwich.) Then punch another slit in line with the first, and repeat a 195,000 times. Be very careful as the edges of the dimpled metal is razor sharp.
Then wash all the grit and dirt off the underside of your floorboards, let them dry, then stick on the insulation. When you’re sure it’s where you want it to be, press hard all over.
Results: Blessed relief from engine, exhaust system, and radiated road heat. A bit quieter, but that was a pleasant side effect. The main benefit is that when the ambient temperature in Texas is 100 degrees, the inside of the car is barely above 100. Especially noticeable on the passenger side under which the muffler is located.

[philosofriend]

Originally Posted by serocontra

would any of these tips be useful on an open car?

Yes, because the metal panels of the body resonate and make a lot of noise. If say the frame that is 4 inches deep is vibrating it can only grab hold of a little bit of air. Hook a big piece of sheet metal to that frame and now the vibration will be efficiently turned into a lot of sound. The low rumbling in particular can come off a large panel.

To make low notes you need either a huge amount of power (like an open exhaust) or a large radiator (like the fifteen inch speakers that bass guitar players love.) Or both!

[philosofriend]

Originally Posted by serocontra

would any of these tips be useful on an open car?

Yes, because the sheet metal efficiently turns mechanical vibrations into sound. The low rumbling vibrations can shake a lot more air through a body panel than they can through a skinny frame rail.