To Dynamat or Not To Dynamat?

I see a lot of freshly repaired / replaced floor pans nicely covered up with Dynamat or equivalent. It looks nice, and I know the advantages with respect to noise and heat. From all the applications I’ve seen, the entire floor, firewall and transmission tunnel are totally sealed, including drain plugs. But let’s face it, British cars aren’t waterproof, and I expect that water will find its way to the metal somehow, somewhere underneath that shiny protective shield. I’ve stripped the interior of my Spitfire down to bare metal and replaced rusted panels. The reason for the rust in the first place was because the previous owner(s) allowed wet carpets to stay in contact with the sheetmetal. I wan to use some type of noise and heat shield, but I don’t want to be dealing with rust again 3 years from now, and I especially don’t want to have to strip out Dynamat to repair it. Am I being too cautious? Anybody have any long-term experience with this stuff?

I'm wondering the same thing. I guess if the car is going to be inside (out of the rain) most of the time, then go with a sound deadening material like Dynamat. I know it will help the sound. My MkI Spitfire was so loud with the top on (no carpets) that I removed the top and have never put it back on.

What about using something like Rhino Liner? It would protect against rust and provide some sound deadening without adding alot of weight. I'm with you on the DynoMat as being a poor choice for this type of application.

Since it rarely gets wet, I used foil faced felt. It's pretty dense and about 3/8 inch thick. I laid it all in, foil side up, then used foil duct tape to create a few large removable pieces. I covered from the front of the front seat sliders forward.

When I unsnap the carpets in my TR3, it's easy to pull the insulation out, from both the floor and the firewall. I've only had to do it once.

Felt insulates for heat and noise really well too.

Jack

I've read good things about this:

www.lizardskin.com

I haven't used it myself, but there are some rod & custom shops using it.

-John

Also beware that that stuff can get real heavy.

I saw somewhere some bonehead put some stupid big stereo in his Corvette and decked it out with Dynomat, said it added 500lbs to the car!!

BTW - If at all possible do not use Dynomat, it is incredibly overpriced! There are many other (very cheap) alternatives.

Dynamat adding 500 lbs to the car? I don't think so. I used Dynamat Extreme and if you do your homework correctly you can find it for a very reasonable price. If you but the stuff from 'car stereo dealers', yes, they will overprice it. But you can search around and it works very well. Also, the comment about cheaper alternatives: you get what you pay for. :)

Like I said before, I used Dynamat Extreme extensively on my TR6. It made a world of difference and I would highly recommend it. I did NOT cover up any of the drain plugs, if you will.

As far as rust: if you prep the surface and use a high quality automotive paint you should have no problems. I do not drive my TR6 in rain therefore this is not a problem for me. Go to my website at bowtie6.com and you can see the work on my car.

joe

I have tested a number of heat & sound insulating materials including Dynamat and Dynamat Extreme. The Extreme version consists of poly-foam and lead so it is VERY heavy and will hold water where you don't want it. Regular Dynamat will add a few pounds, has very good sound insulating and average heat blocking capability. I know of three Healeys using Dynamat and the owners are happy with the result. Lizard Skin did not do well in my testing for heat blocking capability. I used a felt & foil insulation that I can remove with the carpet after being caught in the rain. The cars leak - it's the nature of the beast, best to have something you can pull out and let the floors dry.

Poly foam? Sure about that?

The black tar-like material is non porous and I have tested it on my car and it does not absorb water. On one side is a foil and on the other side is an adhesive. I have separated the two (the black material from the foil) and it does no seem to absorb anything. Perhaps you are confusing it with something else.

However, they do make a hoodliner that is indeed foam-like with foil front. The back has adhesive. I have used this with very good results under the hood.

joe

The Dynamat with aluminum on one side and self-adhisive black goo on the other works very well and does not absorb water. Dynamat makes another product, I thought was called "extreme" that two layers of black ply-foam over a thin lead sheet. Holds water like a sponge and weighs in, like lead bricks, because thats what it's made of. I believe it was made for sound reduction on "DONKS" not old sports cars.

This looks like a nice writeup: http://www.sounddeadenershowdown.com/

I used a product called B-Quiet Extreme. http://www.b-quiet.com/

Out of Canada, so it made it easy.

http://www.gt6.ca/05/12-28/slides/IMG_7464.html

Does a decent job of sound and heat protection.

A.

I picked up some flat roof asphalt repair material (poor man's dynamat) at a local hardware store, but liked the felt (see above) that I did not use it. It was Waaaay less expensive than dynamat.

Jack