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1983 300SD
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Discussion Starter #1
Sorry for posting so much. My restoration is moving along insanely quickly. What an incredible hobby and I'm just super jazzed. But so many questions for the wise ones of Benzworld!

I've been coming across a variety of different types of insulation and foams that need to be replaced because of the smell, degredation or "it's 2019, I think we can do better".

I purchased dynamat extreme, dynapad and frost king. For carpet backing I got 1.5" memory foam and yoga mats in addition to everything else

Where I'm left scratching my head is on insulation that's draped. And foam insulation and seals. I'm not sure what a modern replacement for these is.

A couple of examples of one type of foam from headliner. If you look behind the HVAC box that's some of the draped insulation I was referring to. It's also behind the rear seats.

Anyone have thoughts on what to replace the stuff with? My opinion is the more sound deadening the better.


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SuperModerator
1986/1990 W126
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13,422 Posts
You don't have to worry about posting too much. That's what the forum is for.

I recently redid the rear bulkhead, behind the front seats and underneath them. I used some nice butyl stuff with a kind of quilted aluminium on the upper surface and super sticky butyl on the other. You have to apply it with a roller until all the quilting effect is gone, for the proper effect. (Maximum adhesive without any air pockets.)
It shapes incredibly well to contours etc.

I used the same under the front mats and wherever I saw a spot that could take it, until I ran out.

I had previously done things with sound deadening mats and one thing I have learnt is so not use anything that can contain water! What a bloody mess it was when the car sprung a leak again. It held all the water and was difficult to then extract from under the floors etc.

Doing that rear bulkhead was great because I put in a bass unit in the boot that kicks arse. Possibly all that deadening helped because it sounds so awesome and of course no rattles at all.
 

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Premium Member
1990 SEC
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4,088 Posts
It's a great project you've embarked upon. Enjoy it.

I wouldn't go overboard on the sound dampening material. Too much just adds weight. Plus it's expensive so it quickly adds up. Been there, done that and have the scars to show for it.

Sound deadening has multiple components and they work together.

CLD, or Constraint Layer Dampening (think Dynamat) consist of a layer of flexible butyl (dampening) on thick aluminium foil (constraint). CLD is applied to panels that can vibrate and helps reduce this noise source. You only need to cover about 25% of the surface to get the full effect. Brakets and reinforcement structures don't vibrate so they don't benefit from CLD.

MLV, or Mass Loaded Vinyl, is an effective sound barrier and is used on floors and things like the rear shelf, trunk floor, the panel between the passenger compartment and the trunk, etc. It's heavy, so difficult to use on vertical panels or upside down as you're not supposed to glue it. It looses much of its sound-dampening effect if you do. Works really well on top of CLD.

Closed-Cell Foam, works well underneath panels to eliminate squeaks and rattles. Does not work well as a sound barrier as it only absorbs high-frequency sound and most of the noise in cars is low frequency. Closed-cell foam does not absorb water (closed-cell, duh!) which is a major benefit in cars.

If your original foam is crumbling, I'd use closed-cell foam to replace it. Various thicknesses are available.

Good luck with the project.
 

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1991 560Sec
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68 Posts
Please keep making these posts because I’m in the same position as you are so this is perfect. And this is the second post too! Seems you’re moving a bit faster than I am though.
Ianrandom do you have a link to that butyl stuff you’re talking about? I want it to be precisely what you’re talking about as I plan on redoing the sound system with potentially a bass unit as well so this thread is perfect!
 

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1983 300SD
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Discussion Starter #5
Great information, thanks guys.

I'm going to rethink my sound deadening strategy and incorporate the prospect of leaks. The frost king I have doesn't appear to be 100% butyl but it looks water resistant. Seems important given its application.

Generally, it sounds like for the floorpan I may want to use a combination of frost king, dynapad (strategically) and if that's not thick enough add memory foam. Save the dynamat for doors, hat rack, behind rear seat, way up in front footwells. Exclusively frost king on roof. Then purchase a bunch of different thickness closed cell foam to redo seals. That seem about right?

Any thoughts on the cloth looking insulation/padding? Had to rip out all of mine due to the smell. It's hung up in many places (like behind the dash) and a substitute designed to adhere to stuff wouldn't work in those areas.


Seems you’re moving a bit faster than I am though.
Yeah, my girlfriend and dog are not happy about that. It's literally all I do. Every weekend and every day after work.

Probably a good idea for us to PM each other as we come across issues or interesting ideas on tackling something. A lot of items might not be post worthy but could help each other out.

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1999 E320, 2003 E320 Wagon, 2005 C230K SS, 2010 Accord LX w Eibach & Koni FSD's
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Probably a good idea for us to PM each other as we come across issues or interesting ideas on tackling something. A lot of items might not be post worthy but could help each other out.
Please DON'T be afraid to share! We're all open to new ideas and techniques here.
 

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Premium Member
1990 SEC
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4,088 Posts
Great information, thanks guys.

I'm going to rethink my sound deadening strategy and incorporate the prospect of leaks. The frost king I have doesn't appear to be 100% butyl but it looks water resistant. Seems important given its application.

Generally, it sounds like for the floorpan I may want to use a combination of frost king, dynapad (strategically) and if that's not thick enough add memory foam. Save the dynamat for doors, hat rack, behind rear seat, way up in front footwells. Exclusively frost king on roof. Then purchase a bunch of different thickness closed cell foam to redo seals. That seem about right?

Any thoughts on the cloth looking insulation/padding? Had to rip out all of mine due to the smell. It's hung up in many places (like behind the dash) and a substitute designed to adhere to stuff wouldn't work in those areas.




Yeah, my girlfriend and dog are not happy about that. It's literally all I do. Every weekend and every day after work.

Probably a good idea for us to PM each other as we come across issues or interesting ideas on tackling something. A lot of items might not be post worthy but could help each other out.

Sent from my Pixel 3 using Tapatalk
I looked at the products on the Frost King site and didn't see anything that can be used as a CLD. I'd stick with products such as Dynamat and equivalent. I've used Second Skin products in several vehicles with good results.
https://www.secondskinaudio.com/shop/
There are CLD products on the market that use asphalt instead of Butyl. Steer clear of those. Asphalt turn liquid at high temperatures and makes a mess.

The Dynapad product looks interesting as a variant of MLV.
 

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1983 300SD
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Discussion Starter #8
I looked at the products on the Frost King site and didn't see anything that can be used as a CLD.
Yeah, this is very much a hacky use that's not advertised but is popular in some automotive communities. It's supposed to be a replacement for peel and seal but cheaper and not asphalt. There are strong opinions about it but I was initially planning on doing everything in Dynamat. Some people swear by it. I figured using Dynamat strategically then something cheap, lightweight and didn't smell on every other surface could save some coin. But at this point I've torn up the budget so that doesn't really matter anymore.

At any rate, I overbought a little and then Amazon sent me double because of a shipping snafu... long story short, I'm freaking stocked on Frost King atm. It would be nice to find somewhere in the car to put it.

Since it's allegedly CLD that's why I was thinking FK on the floor where I might be concerned about leaks and then cover that with Dynapad. Wouldn't be a big deal to use Dynamat there instead. I think the question is if the Dynamat is sufficiently resistant to water intrusion and if not whether mitigating the effects of water intrusion is worth leaving it out there. I plan on having this vehicle the rest of my life and it's not going to be in many situations where water will get inside anyway.
 

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Premium Member
1990 SEC
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Since it's allegedly CLD that's why I was thinking FK on the floor where I might be concerned about leaks and then cover that with Dynapad. Wouldn't be a big deal to use Dynamat there instead. I think the question is if the Dynamat is sufficiently resistant to water intrusion and if not whether mitigating the effects of water intrusion is worth leaving it out there. I plan on having this vehicle the rest of my life and it's not going to be in many situations where water will get inside anyway.
Butyl does not retain water and forms a solid seal if the panel it is applied to is reasonably clean. Doesn't have to be super-clean, but must be free of grease and oils. I have had CLD in my SEC for more than ten years with no ill effects and still getting the job done reducing panel vibrations.
 

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1983 300SD
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Discussion Starter #10
Somehow I didn't realize dynamat doesn't retain moisture. I've had some of the stuff sitting in my living room for like two weeks and haven't even opened it because I'm not at that stage yet. Looks like I'm investing some more money in dynamat.

Interestingly, the FK and dynamat appear and feel very similar. But the dynamat is MUCH more dense. Makes sense that it's the choice of budget sports cars. Maybe I'll put some of the FK in my Jeep and see if it reduces the sound of mud coming up over my hood and hydrolocking my engine.

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