Road noise suppression (undercoating)

Back in the 1950s I read an article in Popular Mechanics magazine about a g uy who bought a new 1950 Ford car. He removed the door panels and painted s ome apsalt roofing inside the doors, then he painted that stuff underneath his car. He said it helped prevent rust and also made his car run quieter.

Great stuff is light. You need weight. I used to rub thick roofing tar on underneath.

Greg

Some swear by Dynamat:

I've no personal experience with it.

Small cars are inherently noisy. They are thin and cheaply made. There is not much you can do about it except buy a bigger car. Move up to a Hyundai Sonota or Azera. You will find them much quieter. I rent cars frequently and always wear ear plugs when driving cars smaller than mid-sized.

Road noise is transmitted up through the tires and suspension into the cabin. The suspension is very small and thin. You could try different tires and have soft suspension bushings installed.

certainly not as quiet as my 2000 Silverado pickup.

wheel wells and floor boards be of any benefit? Are there other products? Anybody done this?

My dad had a Dodge Caliber for a short while. I drove it a few times and was surprised that it apparently had nothing to quiet down the large metal panels. It reminded me of a cargo van. It was just unpleasant to ride about in. He replaced it with a Dodge Journey.

My guess is that you should try the stuff on the doors and roof first, if there's nothing there to deaden the sound then it should work. OTOH, I don't have any experience with these products. My gut feeling is that the self-adhesive mats would work better.

Op wants outside stuff. Around here you could just take it to a rust-proofer. The cans of waterproofing spray are not any good, and I found the stuff turns to dust.

Greg

You're absolutely correct. Sorry about that. I didn't know there were shops still doing undercoating. That sounds so 70s. :-)

certainly not as quiet as my 2000 Silverado pickup.

wheel wells and floor boards be of any benefit? Are there other products? Anybody done this?

IMHO: bad idea. I don't even like traditional tarry undercoating as if not meticulously applied promotes rust. I've seen cases in the past where manufacturers experimented with filling body cavities with foam for stiffness and noise deadening (e.g. the roof pillars of the Porsche

914) and almost uniformly they caused rust problems. I've also heard tell of people filling the "frame" cavities of unibodies with quasi-frame rails with expanding foam and as I'm sure you can guess I don't like that idea either unless you drive a car that will never see rain or wet conditions (or even have its underside hosed off.) You won't like this idea, as it's more work, but my suggestion is this: get some Dynamat or similar product (basically, a tar-like material with an adhesive backing on one side and a foil facing on the other - available under many brand names and at many price points) and remove the seats, peel back the carpet. Stick the Dynamat (or other product etc.) to the inside of the floor, and then if it's still not quiet enough, remove the door panels, and stick it to the inside of the outside door skin. (be careful when replacing the plastic water shield that is no doubt there; you want to get that back just the way it came off and have it be well adhered.) You don't need full coverage of the panels with the Dynamat, even a little bit on a large panel will help deaden resonance, but more coverage obviously is better (to a point.)

good luck,

nate

I've used roofing tar as seam sealer on the undersides of vehicles... actually works fantastically. I repaired a rocker panel on my dad's '73 Chevy pickup back when I was in high school and before I had a welder, I used sheet steel, roofing tar, and pop rivits. Once the rust hole was patched, I sprayed asphalt undercoating over for some texture, then covered the whole mess with some brush on Rust-Oleum. You laugh, but the last time I looked under that truck (many years later) that repair was still solid. Roofing tar = good stuff.

nate

Ziebart.

Greg

Hearing aids work in a tough environment. In the old days, the standard practice was to coat the electronics with some greenish-blue stuff or wrap the circuit in silicone. I never liked that stuff. The wraps trapped moisture as did the protective coatings once moisture took hold. They also made re-soldering joints harder. That would have been ok if the coatings actually worked. They did not. It was aggravating that the manufacturers seem to have no clue about this.

These days the corrosion protection coats seem to work better and most aids are coated with a water resistant nano-coating. I don't know how it works but it's supposed to be miracle stuff. I like miracles. :-)

I find no end in the amusement of how some posters will respond and offer a fix to a problem without any acknowledgement whatso- ever that the very same either approach or solution has already been suggested, leaving me to wonder whether they're in fact that obtuse themselves or simply hope and trust that their audience will be. ;

does a stooopid trying to eat a stoopider make a stooopiderer? it looks like you're trying to show us.

Missed spots rust faster out of spite?

How can you tell undercoating accelerated the oxidation process? -----

- gpsman

I have heard the story many times that it can Promote rust. Fact is, aftermarket application start to crack after 3-4 years. Water gets in and stays there. You have to do another application for the cracks. I had factory applied soundproofing attached to the bottom of my datsuns that never cracked, and was extremely difficult to remove. No rust when water cant get in.

Greg

Urethane pickup bed coating. Or Rhinoliner, something like that. You can buy it and paint/roll it on yourself. Some people have applied it to other things other than pickup truck beds. They say it works great.

I knew I had it bookmarked somewhere.

Interesting, but irrelevant.

All undercoating material is identical, or behaves identically?

When it "cracks", it cracks all the way to the metal, then retains that little moisture to a sufficient degree to accelerate rusting?

Is there some lack of meticulousness of application that causes cracking, every single time?

Huh?

That's good info, I guess. -----

- gpsman

When it's too thick, it cracks, and starts peeling back. Occasional thin coats is the way to go.

What part didn't you get. I didn't ask for it. It came like that.

Greg