Sound deadening. What to use

I want to add some sound insulation to the Molvo. While the sound when you are stsanding outside is not bad, inside the car it is too loud.

So what to use? Starting with the rear deck I was thinking of something like the firewall mat that comes on the Miata, kind of a rubber/fiber mat sandwich. but have no idea of what I would be looking for or where to buy in bulk.

There are a few spots where the dynamat kind of tile would help with some resonance type noise, but I am not a believer in the wall-wall dynmat approach that I see a lot of people use.

Gotta be some audiophile people here with experience in this stuff.

Pete

In reply to NOHOME :

Pete, I know there are several folks in here that have used lizard skin with good results. I’m following for the Ramcharger. It too needs quieted down on the inside.

Paging Dr. DusterBD.  Duster to the white courtesy phone.

I'm not much help, but have heard patches of dynamat style stuff are effective, for instance, just a 1'X1' square on a floorboard, instead of covering the whole thing. Kind of like OEM, so makes sense to me. Note: I have no actual experience doing it this way.

Depends on what you want to achieve. Dynamat (ie butyl/mass loaded vinyl) et al is good to quieten panel vibrations. You should see reasonable improvements from partially covering panels already, although getting the positioning and sizing right to change the resonant frequencies of the panel requires some science and/or experience. That's one of the reasons people tend to cover the whole interior.

For car audiophile installations the Dynamat type materials are usually only the bottom layer, to quieten things down further, you need another layer of sound absorption material on top.

At some point you need to stick a turbo on the engine to counteract all the extra weight .

Keeping in mind I haven't done this before, I think a combination of small areas of Dynamat and then covering everything with Dynaliner would work well and give you a sound control. The spray on stuff seems like it would take a million coats to get as thick and effective as the roll materias.

In reply to dculberson :

Off to Google Dynaliner

Ill be back after work.....

First off, most important, make sure there are NO AIR LEAKS.  A very small air leak can transmit a LOT of sound.

As noted putting a 6 inch square in the middle of a door skin is about 80% as effective covering the entire door, so you can use it sparingly.  Also Dynamat is super expensive for what it is.  You can find similar material fro much cheaper (you just need something heavy, rubbery and flexible), the primary difference might be the adhesive, so you might need to upgrade that.

The spray on might be useful in some areas (and probably good for pluggin leaks), but mass is important, so a square of mat is likely better on a flat panel.

Jute mat (normally under carpets) is cheap, light and good for higher frequency noise.

In reply to aircooled :

There's some bitumen foil backed material available that can be used, but as some people found out, it helps if you like the smell of a freshly installed roofing membrane .

That said, there are a bunch of butyl off-brand materials around that are supposedly pretty good an considerably less expensive.

aircooled said:As noted putting a 6 inch square in the middle of a door skin is about 80% as effective covering the entire door, so you can use it sparingly.  Also Dynamat is super expensive for what it is.  You can find similar material fro much cheaper (you just need something heavy, rubbery and flexible), the primary difference might be the adhesive, so you might need to upgrade that.

...Stick-on wheel weights?

Heck, some of them are dense rubber, not steel or lead.

I currently have a 1/4" thick rubber matt, but it is not bonded to the steel flat rear deck and it stinks of rubber fumes.

Pete

So....

Its after work. This is going to be quick and dirty because i want to get the diff back in the miata, nachos and cheese, and a nap. By 8pm est... 

Theres 4 areas of noise. 

1. Panel resonance. This is what dynamat targets. If you rap your onuckles against any part of a panel and get a bong/rattle/ting or really anything other than a knuckle thud, start with dynamat. 50-80% coverage usually does 99% of what its going to fo. However, guys miss using it on the backs of door panels, in beyween the roof and roof support where theres that little 2/8 gap, etc. I use McMaster carr mastic. Its 20ish gor a 3x4 foot sheet. Heat gun to soften and REALLY work it into nooks and crannies with a j roller and various sticks. This will take care of 99% of loe frewuency noise. The stuff you dont notice, but bothers you yhe most in the back of your brain.

2. Ambient . Tire noise. Guy next to you. Exhaust (to a point). Generally, road noise. We hangldle it with two prodects here in redneckistan. First is reflectix insulation glued right to the panel. Thats the foil plated bubble erap you get at lowesdepot. It acts as insulation (yay!) And an acoustic decouple layer. Its suprising how much it changes on its own. However, over that we use foil backed jute. Glue this jute side down to the panel civered in dynamat/bubble wrap. This will take care of most road noise. If room, layers behind interior side panels and headligher make huge differences. Additionally, auto custom carpet has begun to offer mass backing to their carpet. Its a layer of 1/8 rubber like all new cars since the 80s (lucury) have had. Its AWESOME. 

3. Dynamic: exhaust, engine. Youre on the right track with a firewall pad. But at the end of the day, you can only do so much about the actual noise they create. Adding a few layers of extra soind proof nearby helps, as well as heat shields underneath to deflect the sound waves away from the body.

4. Point. Wing windows. Door weatherstrip. Etc. Fix issues, and sometimes remember that its a 50 year old design, its as good as its gonna get.

I use the cheap hardware store butyl flashing. Smell it first, a few brands stink, but most are okay. Watch a few videos on installing it. I tend to hit panel resonance (both metal and plastic!) first with strips or x's, then seal problem areas, and then use whats left over for general deadening around trans tunnel and fender arches. I then cover the lot in cheap fiber padding where needed. Fabric tape between plastic seams, around a/c and door lock linkages, bundles of wires, etc does wonders for rattles. 

Dusterbd13-michael said:

So....

Its after work. This is going to be quick and dirty because i want to get the diff back in the miata, nachos and cheese, and a nap. By 8pm est... 

Theres 4 areas of noise. 

1. Panel resonance. This is what dynamat targets. If you rap your onuckles against any part of a panel and get a bong/rattle/ting or really anything other than a knuckle thud, start with dynamat. 50-80% coverage usually does 99% of what its going to fo. However, guys miss using it on the backs of door panels, in beyween the roof and roof support where theres that little 2/8 gap, etc. I use McMaster carr mastic. Its 20ish gor a 3x4 foot sheet. Heat gun to soften and REALLY work it into nooks and crannies with a j roller and various sticks. This will take care of 99% of loe frewuency noise. The stuff you dont notice, but bothers you yhe most in the back of your brain.

2. Ambient . Tire noise. Guy next to you. Exhaust (to a point). Generally, road noise. We hangldle it with two prodects here in redneckistan. First is reflectix insulation glued right to the panel. Thats the foil plated bubble erap you get at lowesdepot. It acts as insulation (yay!) And an acoustic decouple layer. Its suprising how much it changes on its own. However, over that we use foil backed jute. Glue this jute side down to the panel civered in dynamat/bubble wrap. This will take care of most road noise. If room, layers behind interior side panels and headligher make huge differences. Additionally, auto custom carpet has begun to offer mass backing to their carpet. Its a layer of 1/8 rubber like all new cars since the 80s (lucury) have had. Its AWESOME. 

3. Dynamic: exhaust, engine. Youre on the right track with a firewall pad. But at the end of the day, you can only do so much about the actual noise they create. Adding a few layers of extra soind proof nearby helps, as well as heat shields underneath to deflect the sound waves away from the body.

4. Point. Wing windows. Door weatherstrip. Etc. Fix issues, and sometimes remember that its a 50 year old design, its as good as its gonna get.

What would be the best product for floor pan underneath factory carpet?  Like you mentioned the 1/8 rubber mat that Auto custom carpet offers, could you install a rubber mat underneath factory carpeting as the best value solution for floor pan?

https://www.accmats.com/articles/everything-about-mass-backing/

In reply to engiekev :

Every now and then, Summit sells garage floor pad mat things in a maybe 4'x6' roll for $10 or so.  Might not be a bad place to start?

This stuff

engiekev said:

Dusterbd13-michael said:

So....

Its after work. This is going to be quick and dirty because i want to get the diff back in the miata, nachos and cheese, and a nap. By 8pm est... 

Theres 4 areas of noise. 

1. Panel resonance. This is what dynamat targets. If you rap your onuckles against any part of a panel and get a bong/rattle/ting or really anything other than a knuckle thud, start with dynamat. 50-80% coverage usually does 99% of what its going to fo. However, guys miss using it on the backs of door panels, in beyween the roof and roof support where theres that little 2/8 gap, etc. I use McMaster carr mastic. Its 20ish gor a 3x4 foot sheet. Heat gun to soften and REALLY work it into nooks and crannies with a j roller and various sticks. This will take care of 99% of loe frewuency noise. The stuff you dont notice, but bothers you yhe most in the back of your brain.

2. Ambient . Tire noise. Guy next to you. Exhaust (to a point). Generally, road noise. We hangldle it with two prodects here in redneckistan. First is reflectix insulation glued right to the panel. Thats the foil plated bubble erap you get at lowesdepot. It acts as insulation (yay!) And an acoustic decouple layer. Its suprising how much it changes on its own. However, over that we use foil backed jute. Glue this jute side down to the panel civered in dynamat/bubble wrap. This will take care of most road noise. If room, layers behind interior side panels and headligher make huge differences. Additionally, auto custom carpet has begun to offer mass backing to their carpet. Its a layer of 1/8 rubber like all new cars since the 80s (lucury) have had. Its AWESOME. 

3. Dynamic: exhaust, engine. Youre on the right track with a firewall pad. But at the end of the day, you can only do so much about the actual noise they create. Adding a few layers of extra soind proof nearby helps, as well as heat shields underneath to deflect the sound waves away from the body.

4. Point. Wing windows. Door weatherstrip. Etc. Fix issues, and sometimes remember that its a 50 year old design, its as good as its gonna get.

What would be the best product for floor pan underneath factory carpet?  Like you mentioned the 1/8 rubber mat that Auto custom carpet offers, could you install a rubber mat underneath factory carpeting as the best value solution for floor pan?

 

https://www.accmats.com/articles/everything-about-mass-backing/

Honestly, it depends on which of the 4 noise types youre targeting.

On cars with factory carpets in good shape, i do everything outlined except the mass backing with very good results. You should take a rude in my 70 duster with three inch pipes.....

In reply to Knurled. :

That is what I have in the rear deck now. It has a distinctive aroma . I think it would work better if it were more attached to the sheet metal deck.

Pete

In reply to Dusterbd13-michael :

2. Ambient . Tire noise. Guy next to you. Exhaust (to a point). Generally, road noise. We hangldle it with two prodects here in redneckistan. First is reflectix insulation glued right to the panel. Thats the foil plated bubble erap you get at lowesdepot. It acts as insulation (yay!) And an acoustic decouple layer. Its suprising how much it changes on its own. However, over that we use foil backed jute. Glue this jute side down to the panel civered in dynamat/bubble wrap. This will take care of most road noise. If room, layers behind interior side panels and headligher make huge differences. Additionally, auto custom carpet has begun to offer mass backing to their carpet. Its a layer of 1/8 rubber like all new cars since the 80s (lucury) have had. Its AWESOME.

I think I will concentrate on this aspect first. The foil bubblewrap I can get at Home Depot. Foil backed jute sounds like a good idea even on its own, any contacts on where to purchase?

Pete

In reply to NOHOME :

I was able to order a couple of giant rolls from Home Depot a few years back for something like 50 bucks and roll. I still have some. So not sure of current pricing. I know Dad got some off Amazon but it seemed high-priced to me.

They still have it just not quite as cheap. Home Depot website. Called a Radiant Barrier with recycled cotton.

In reply to Dusterbd13-michael :

This stuff? https://www.homedepot.com/p/UltraTouch-48-in-x-24-ft-Radiant-Barrier-with-Recycled-Cotton-30000-11424/100661257

In reply to Matthew Kennedy :

Yup! Thats the foil backed juste i use. Been real happy eith it.

In reply to NOHOME :

I have one of my cars covered in Reflectix and it does nothing for noise. I would try anything else.

Edit: no experince with the jute stuff.