How do you reduce cabin noise

I have been driving my replica Coupe for about a month now, and I came to realize that it is not very comfortable to drive on the freeway faster than 70 mph. It is more due to the noise in the cabin more than anything else as it track straight and handles well.

I am not sure how it is with the Speedsters as I imagine the wind noise at that speed might be louder than the engine and trany noise, but in the coupe it is really loud. Any suggestion on how to reduce the noise level in the cabin. Anybody has experience with Dynamat?

Any suggestions are welcome.

Thanks

Theron recommends Bituthene.

https://www.speedsterowners.com/forum/readmsg.asp?t=7775

You could try the "Harley" solution - wear ear plugs and remove all the mufflers. You won't hear the wind at all then.

Or you could try the "Bose" solution - put a 15,000 Kw amp and some 12 inch woofers in the back seat and crank it up.

Sorry about that.

Eddy, I've been pleased with the results I obtained from a product called B-Quiet, which is a clone of Dynamat. For best results, particularly in a closed car, I think you'll also want some of the thicker stuff (who's name escapes me). The Dynamat-like products basically damp out vibrations, while the thicker stuff, when used in concert with Dynamat (or other) will provide some accoustic insulation. The problem is that proper installation would mean pretty much ripping out your interior to install the appropriate product under the carpet, above the headliner, on both sides of the firewall, in the doors, etc. How badly do you want this?

I compromised with the B-Quite in the doors and on one side of the firewall. It helped, but it's still kinda noisy - moreso with the top up than with it down.

So, Lane......


How quiet is Pearl compared to your Speedster?

Just curious.....

Dear Lane, thanks for your comments, I was thinking to put it against the firewall and the floor behind the seats as they were above the transmission, however, I have to see how difficult it is to take off the upholstery parts, the door might be actually the easiest as the panels are screwed to the body and I don't plan to touch the roof as the headliner seems to be a pain to re do

Eddy,


I guess you have spoken to JPS. I heard (have no details) that one of the "fixes" done on Dewalt's Coupe by JPS was added soundproofing. What that was, and how it works, will have to come from Tom. What I see mentioned here is stuff you put on the inside, w/ the carpet over. Is there anything that can be put on the outside, (under the car, in the back cavity by trans, etc. firewall) thereby by-passing the tearing up of the insides to do it?

dynamat in the engine bay helps, but it should be place on the back-side of the rear seat

G-man: Pearl is much quieter, but some of that is your exhaust. When I get the new one on we can do a better comparison. Did you put sound insulation under the carpet, etc.?

One issue with the Beck is that there aren't the two walls of fiberglass between the engine and interior. Instead, the Beck has a shelf in front of the engine, making the wall on the other side of the interior carpeting the only sound barrier.

Dymamat works good and is very waterproof. But the foil back Jute padding is a much better chose for a coupe. Sence you wont have the top down and don't have the risk of getting it soaked in a rain.

Its a good insulator an covers the sound very well. try Jegs or Summit racing

Lane:

Good point about the shelf in front of the engine. That would tend to make things a bit noisier in the cockpit, and your exhaust note has a lot more "Rap" in it than mine.

I used 3/8" thick, shop floor padding all over the place. Mostly held in with very liberal use of 3M upholstery adhesive and DAP contact cement, it is used on the engine side of the firewall (I used under-hood "mushroom" fasteners on that), under the carpet in the rear seat area, under the rear seat, under the carpeting everywhere in the cockpit and inside of the doors (glued to the inside of the outer skin). I honestly have no idea of the amount of sound proofing it provides, but when I was still working and building a bunch of high end "sound proofed" conference rooms, the stuff the contractor put on the walls looked a lot like shop floor padding, so that's where I got the idea.

Seems to do the trick and gives the doors a nice "thunk" when they're closed. Also, if I pull out the floor carpeting, I have a nice, black, rubber floor mat sitting there (which doesn't seem to absorb water, either).

I tried the Bituthane roofing material and found that it didn't seem to work as well as what I had originally, so I went back to that (and still have half a roll of the roofing stuff kicking around, too).

gn

What am I missing? The noise in my Speedster is not at all onjectionable. What sounds I hear are pleasant.---Jack

As are mine - most of the time. However, as you'll find out on the drive to Carlisle, it can get old after a while. Also, in a coupe (or a Speedy with the top up) the sounds are considerably different from a Speedy sans top.

i have noticed in my D with the top up and the windows closed the engine noise is more noticable.

Im sure a coupe would be even more so.

I like the Dynamatt in the doors and yes it does make the door sound more solid when you shut them.

It would be perfect in the area just behind the engine But I still would add some inside the cab to further improve the sound deading.

More Is MORE ..The more you inprove a car the better the car

Jack:

On a long trip (for me, "long" is anything over two hours) I find the wind noise far more objectionable than the engine noise.

I just put in a pair of those mooshy foam earplugs and crank up the radio/IPOD.

I used to have more valvetrain noise (it was pretty loud, in retrospect), but that got quieter when I replaced my rocker shafts so now I can actually hear the tires on the pavement (some of the time....).

gn

I just learned about a sound reduction coating. The website link is http://www.quietcoat.com/index.html .

I think it would be easier to apply than mats and it could be installed in places like the underside of the pan if you didn't want to pull up your carpet.

Of course, the website claims that it works much better than Dynamat.

Does anybody have experience with the Quietcoat product? Looks intersting.

Marty G.

I bought 1 gallon of the Quiet Coat and applied 3 layers on the firewall in the engine compartment, under the back (seat) area above the transmission (from underneath) and I think it reduces the engine noise a bit. I have not driven at 70 mph for an extended time, but now it seems more bearable (or my ear is getting used to it). I figure it is worth to try and I don't have to take apart the interior. Small improvements at a time.....

how do you reduce cabin noise... my first thought when I saw this again was not to let my wife ride with me...

I'm tellin', I'm tellin'!