Replacements for crumbled rear foam pads

[kobachi]

I've got my interior torn apart for a stereo upgrade and noticed all of the yellow foam pads (with rubber? layer) are crumbling apart. Like this one:

https://store.delorean.com/p-10067-rr-tnl-insl-pad.aspx

This material is also coating the back wall right under the rear window, and some of it is quite sticky/goopy. Does anyone know what this material is called and what a suitable modern replacement would be? I was looking at Dynamat products to insulate sound from the engine, but Dynamat has like seven different products now and I can't tell which would be most appropriate for this kind of application.

[jawn101]

That stuff is just carpet padding, available at any home improvement store. I got a few square feet of it for free because it was a cut piece that wasn't big enough for anyone to use for carpeting.

[jawn101]

Sorry. I should say the yellow stuff is just carpet padding. That thick rubber mat is just that - rubber. But it lays on top of a layer of padding that the throttle cable passes through, and provides sound deadening from the transmission.

[kobachi]

Thanks for the info. Would DynaPad be an appropriate replacement for the carpet pad? Or would that be overkill?

[DMCMW Dave]

Thanks for the info. Would DynaPad be an appropriate replacement for the carpet pad? Or would that be overkill?

Dynamat damps resonance in the panel. It doesn't do much to block sound. Dense foam is better for that. Ideally you use both.

[kobachi]

Dynamat damps resonance in the panel. It doesn't do much to block sound. Dense foam is better for that. Ideally you use both.

Thanks, but dynamat is not the same as dynapad. You describe the former accurately, but the latter is a different product from the same company.

[dmc6960]

The stock "foam pads" are a loaded mass damper (unsure of composition and density) decoupled from the body with Juke (carpet padding). Dynapad would give you similar characteristics with a 1lbs/sqft loaded mass damper sandwiched between two 3/16" urethane foam layers. The foam layers are not very thick though. I'd suggest dynamat on the fiberglass, with at least a 1/2" dedicated closed cell foam, topped off with this as your loaded mass damper.

Since you seem willing to shell out the $$$ for Dynamat products, I'll save you my lecture about using cheap asphalt-based alternatives.

[kobachi]

The stock "foam pads" are a loaded mass damper (unsure of composition and density) decoupled from the body with Juke (carpet padding). Dynapad would give you similar characteristics with a 1lbs/sqft loaded mass damper sandwiched between two 3/16" urethane foam layers. The foam layers are not very thick though. I'd suggest dynamat on the fiberglass, with at least a 1/2" dedicated closed cell foam, topped off with this as your loaded mass damper.

Since you seem willing to shell out the $$$ for Dynamat products, I'll save you my lecture about using cheap asphalt-based alternatives.

Solid, thanks for the information. I'm not going to use asphalt-based alternatives, but I'm more than willing to entertain other alternatives, if you have recommendations on other vinyl/butyl/foam-based equivalent products that aren't the $$$$ of DynaMat products.

[dmc6960]

McMaster-Carr used to sell loaded mass vinyl, but unfortunately they do not anymore. They still have standard acoustical foam which is great for absorption in general areas (open-cell with sealed ends). I've also used 1/8" true closed-cell in smaller areas. I was able to obtain a fair amount of standard 1lbs loaded mass vinyl from a local audio dealer so I've used that on top of the foam in all applicable areas (even double/triple layering it in some spots). Use a good urethane adhesive between layers. Dynamat is still what I recommend though for the resonance reduction on the panels themselves, before any foam or blocking layers are added.

[kobachi]

McMaster-Carr used to sell loaded mass vinyl, but unfortunately they do not anymore.
Are you familiar with http://sounddeadenershowdown.com/? Looks like they sell all the various products you speak of. Although this all seems more designed for rattling steel panels than a fiberglass unibody.


Dynamat is still what I recommend though for the resonance reduction on the panels themselves, before any foam or blocking layers are added.
To which panels are you referring? My post was about the padding+rubber panels between the relay box and lambda box (over the transmission), and the similar material that seems to be spread around the firewall (under the rear window). Neither of these have panels over them that would resonate -- it's carpet and air.

Are there places/panels in particular on the DeLorean that would benefit from actual Dynamat that I'm missing?

[dmc6960]

All of the broad flat fiberglass areas resonate like a drum. Its a much lower tone than typical steel panels, and much harder to block. There are 3 major areas of the interior and one minor one which should all be treated. The drivers and passenger side floorboards under the carpet in front of the seats, the trapezoid above the transmission on the rear shelf between the electrical bays, and the rear wall under the rear window. Due to the proximity of the engine, the rear wall and the rear shelf got the OEM sound treatment and should get extra if anybody is actively replacing it in that area.

[dmc6960]

Are you familiar with http://sounddeadenershowdown.com/? Looks like they sell all the various products you speak of. Although this all seems more designed for rattling steel panels than a fiberglass unibody.

Yes, they sell very good stuff there, and the products are a bit more refined than the industrial McMaster-Carr stuff. Properly applying everything will reduce noise in the car. Just don't expect it to be tomb quiet or you will be disappointed.

[kobachi]

Yes, they sell very good stuff there, and the products are a bit more refined than the industrial McMaster-Carr stuff. Properly applying everything will reduce noise in the car. Just don't expect it to be tomb quiet or you will be disappointed.

Oh I'm certainly not looking for quiet as a tomb. I'm not even planning (yet) on doing a full noise reduction job on the car. I just want to replace the gross carpetpad/rubber panels. They are badly crumbled and (literally) melting off the car in some places. They're sticky and gross. I just want to find the best material for replacing those panels to start with. I can handle the rest of it later.