Back shelf foam

[Bitsyncmaster]

I am looking to replace the center foam and broken black "rubber" pad that was OEM on the back shelf. I measure about 30" x 16" is needed. I looked at dynomat but they don't tell how thick it is. I was thinking of just getting a rubber top sheet and putting foam under it. I can get a neoprene sheet as thick as I need but it's pretty expensive.

What have you all done for this fix?

I see the throttle cable needs a channel cut into it also.

[AdmiralSenn]

Dynamat is THIN unless you're thinking of a foam alternative (a lot of the people that sell this type of stuff make filler foam products too). But regular dynamat is something like 1/4" thick if that. You could easily install it with regular foam and not tell the difference, but it won't fill up the space at all.

Dynamat is pretty good, just don't go nuts and plaster the area with it - you don't need very much to accomplish what it's supposed to do. Covering the area just costs (and weighs) more.

I'm actually still on the factory foam...

[jmpdmc]

I used the Extreme and Vcomp products from here: http://www.b-quiet.com/index.html
I ripped out the old foam and put these products on the rear parcel shelf and a few other places. It worked better than what was there and was cheaper than Dynamat when I did it in 2006. I am still happy with it.


Jeff

[1batt4u]

One crazy idea I have had, that is also a good idea. I have a Foam Mat I bought form sports authority: http://www.sportsauthority.com/product/index.jsp?productId=10969806&cp=&sr=1&kw=foam+mat&origkw=foam+mat&parentPage=search Still new in box after so long!! LOL! it is 2x6 feet, I'm sure you can cut it up!! It is 1cm thick!

[dmc6960]

The ideal setup is...

Bottom layer - Resonance reducing layer - Dynamat eXtreme or similar NON-ASPHALT based product. Your looking for a 100% bytul based product.

Middle layer - High density closed cell foam - Absorbs higher frequency noise and acts as decoupling layer for top layer...

Top layer - Loaded mass damper - Thick/heavy vinyl, usually about 1lbs/sq/ft, helps block whatever noise gets through the bottom and middle layers.

If you really want some good soundproofing, do another layer of foam and loaded mass damper.

McMaster has what you need in industrial supply for the foam (Page 3494 Part #5692T61 or 5692T49) and loaded mass damper (Pages 3497 part #54665T32) . And even though everyone says Dynamat eXtreme is a ripoff, it really is the best product for its job. Cheaper asphault based roofing products will break down after a few years cycling in heat and cold.

[Byrne H&A]

Incorporate expanded metal (screened vent) over the elecrical compartment and avoid more fuse box melt down.

[JIMJAM]

I ripped out every bit of that stinky red, white and blue mystery foam in my entire car and dynamated it. Also did the rear shelf,vertical back wall and replaced the foam on that board. Almost to silent now as I can barely hear the engine. One of the worst noise offenders was when I took off my stick boot I could see the ground. Early vin did not have the rubber boot. If you need to see some pics or any specifics,tips I would be glad to help. I also have a few boxes of dynamat left over. If you decide to buy some I can get it about 1/2 off. Or at least I could.


I ordered some of that ss steel spray paint. I took out the stock grey rear shelf carpet and got some black from Lowes. Cut it as stock but left off the corner covering the elec panel. I then cut this wood that had holes predrilled although I did bore a few out. Painted it and here ya go.

[TTait]

I can recommend the soundproofing kit from Hervey - http://www.specialtauto.com/delorean-parts/accessories.html (1/3rd of the way down)

I did a lot of dynamat (a competitor actually called fatmat), the foam kit, and a new carpet kit. The car is a lot quieter, and it may have helped the low end of the audio system, but it's hard to say as the new speakers went in at the same time.

See this thread for more info on that project and peoples experience with these products:

http://dmctalk.org/showthread.php?439-New-carpet-soundproofing-and-dynamat-any-tips

Info on kick ass speakers (Infinity) for a great price look here...

http://dmctalk.org/showthread.php?572-Choices-of-speakers

(Note that for these front speakers you need coupling nuts off ebay to install them on an oem dash - no modification to install them on the reproduction dash - read the whole thread)

[john 05141]

I have the insulator and the new carpet set from Hervey, + dynamat. installed that 3 years ago, very good. Teh insulator can alsmost be compared with a thick diving suit material.
for the record, I'm talking about the the insulator BEHIND the rear shelf.

I did nothing under the carpet in the cargo area besides Dynamat. Maybe the same insulator as behind the wooden shelf would be an improvement again.

John

[Spittybug]

Can't remember if it was Lowes or Home Depot.... In the carpet/flooring area they have a big roll of 1/2" thick or so thick gray spongy mat material used for cushioning at work stations. It isn't a carpet underlayment, it is stand alone stuff. It's closed cell rubbery foam that is pretty light and not expensive. I cut it to shape and glued it down on the back deck. I'm pleased with its sound deadening, absence of smell and cost.

[David T]

A good substitute if you feel you have to remove the old foam is to get some cheap carpet underpadding and lay Dynamat or something like it on top. You do have to be careful with products like Dynamat, it is HEAVY! Overusing it will add significant weight to the car but it WILL make it quieter. An alternative is to just lay some Frost Guard over the old, cracked up stuff. It is used on roofs to prevent damage from ice dams and has glue on one side.
David Teitelbaum

[dmc6960]

Dynamat (extreme) is designed to be a resonance reducer. It should be applied directly to large sheets of metal or in our case fiberglass. On top of that you want your foam, then on top of that you want your mass loaded barrier.

The same concept was used with the original soundproofing, minus the dynamat/resonance part. Foams and Vinyls have advanced greatly since then so replacements are a big improvement.

Yes, they are very dense. A good mass loaded vinyl barrier is about 1lbs per square foot. Dynamat extreme is about .55 if memory serves me correct. You NEED ALL THAT WEIGHT. Its the only way to soundproof in such a small area. Also keep in mind, adding a 20lbs box of soundproofing will NOT add 100lbs to the car. It will add no more than 20!

Edit - Carpet foam is what was originally used there. While it works, it is marginal at best. There are MUCH better alternatives available like true acoustical foam or in more generic form the open floor matting mentioned previously.

[Chris 16409]

I am looking to replace the center foam and broken black "rubber" pad that was OEM on the back shelf. I measure about 30" x 16" is needed. I looked at dynomat but they don't tell how thick it is. I was thinking of just getting a rubber top sheet and putting foam under it. I can get a neoprene sheet as thick as I need but it's pretty expensive.

What have you all done for this fix?

I see the throttle cable needs a channel cut into it also.


Dave, I had the same situation. The black rubber in my car was all deteriorating. I went to the hardware store and found some rubber with the same thickness and just cut it to fit. The carpet padding underneath was still okay so I just left it in place.