Creating a new vapor barrier for the door
 

Hello everyone -

The car I've been helping a buddy fix back up is getting nearer to going through each door and fixing/installing/restoring things. The car as it sits has no vapor barrier (the clear plastic sheet between the door panel and door).

I would like to go with something that will -

- Be fairly straightforward to install
- Be able to peel it back to service door components in the future and re-install without having to remove and throw it out
- Do the job properly

I will be installing keyless entry on this car with a JDM power door lock actuator. There will be a speaker up front but no crazy stereo stuff.

Ideas and things you guys have tried would be awesome.

Thanks!
Dale

Hi Dale,

This probably doesn't meet your second criteria, but I have used foil-backed sound deadening material with great success for the doors. The added weight is negligible, but helps rid the doors of the hollow feeling/sound. I think it also helps reduce some outside noise (subjective) and added to the overall speaker sound quality. If you ever need to service, you could either peel it back, which may not always be possible, or just remove and add a new section.

Jehan

Seems like you wouldn't need the sound deadening over the open holes in the door. I can see it being on the metal of the door, though. We may do some sound deadening inside the door as we did put some Dynomat down in the hatch and under the carpet.

Dale

Dale,
In my build thread if photo bucket allows the pictures to show, I made new water shields from the clear plastic vapor barrier that you get from Lowe's or Home Depot to use under your house. It's like $10 for a roll.

I used plumber's caulk to hold it on. It can be easily removed/reattached.

For some reason I think you can get them new from Mazda for cheap.

Vince

Yeah...rope caulk or double-sided automotive tape works ideal.

I recently did this (sound deadening), although I didn't close off the hole or replaced the vapor barrier. That said, I think it's worth doing as the door is much less tinny when knocked or closed and I'm sure it will be way quieter when I hit the road.

T

To attach the vapor barrier to the car door use butyl tape sealer. You can peal off and reattach the plastic sheet many times and it stills stays soft, sticky, and water proof. The specs say that it will stay soft and seal for up to 30 years.

Good advice on the butyl, that makes a lot of sense. I'll look into how much they run new from Mazda or if it would be worth getting a sheet of Visqueen or something from Home Depot.

Any other ideas are appreciated!

Dale

The stuff you need is called VB-2 and it’s made by Cascade Audio.

Mineral filled vinyl-copolymer - damper

I used this material on my daily and replaced the vapor shield and what a difference it made in sound quality! The speakers were night and day better and it was easy to work with.

As Jehan pointed out, if you need to service the door, simply cut a slit in it or a section and access what you to and when you’re done, just stick some more of it on top to seal the hole. How often you’ll actually need to go into your door, I don’t know but you can in the future.

And because it’s a sound barrier it will reduce the outside noise and clean up some rattles from the panel.

Nick

Wow! I like that, it looks really sharp installed in the link above.

Dale

Hey dale if you find a new way of making one or used the above product please make a writeup :)

I think I'll have to import some of that VB-2, looks ideal for the job :cool:.

I used it in my Camry...I’m tellin you guys it’s good stuff. Only word of caution, don’t get too much extra. I bought a whole roll for future projects and come to find out the adhesive only lasts about two years without being applied. Once you apply it, it lasts forever but for whatever reason it won’t really stick after a couple years if you haven’t used it yet. Now, I need to find some contact cement in order to apply it to the RX-7 doors.

I also used a thicker “dyno mat” like material from Cascade for the outter door skin on the Camry and the 7, that stuck just fine.

If you want to see the material in other uses, I sealed up my door speaker adapters with it as well. Check my build thread, first or second page.

Nick

Nick,

That stuff looks good. Nice find.
Vince

garbage bag and tape! its not very exciting, but it works and its cheap

That VB2 stuff looks nice. Something inexpensive would be heavy clear vinyl that is sold a fabric shops.

At $90 per door that's expensive stuff.
14 Square Foot Sheet 37" x 54"

Once it is on can you peel it back and reseal it again if you have to get behind the door? I would hate to have to buy another sheet because I had to get behind there just to replace another broken plastic lock mechanism clip.

Any idea how much is needed to properly apply to each door?

I don’t remember it being as expensively as you’re quoting. It was like 5 years ago but I recall paying something like $60 for a roll, a big roll. Enough to do 4 doors no problem.

I dont know how easy it is to unstick and restick cause I’ve never had to do it.

I wouldnt recmend you use a cheap plastic or a garbage bag. You do realize we drive JDM royalty right? We have special cars....don’t use the cheapest shit imaginable...

Nick

THANK YOU, I wish more people would think this!

I imagine there could be a way of making that stuff removable, maybe putting down a layer on the door metal then having another piece that covers the hole in the middle that can come off with some sort of attachment.

Dale

Dale,

The question to ask is what are modern cars using as a vapor barrier? The plastic sheet and bead of tar has been used for many decades and works. It is a simple, light weight, and effective solution. Is there a need to re-invent the wheel? I would argue that repeating the original method of moisture (vapor) protection maintains the car's JDM royalty as Nick kindly mentioned.

Do we need to artificially elevate the FD to demi-god or god like status? If so, then chances are the road along Mt Olympus is unimproved and atop its peak is a Toyota HiLux. LOL

Cheers,
George

Dale,

I believe the Miata forum has the answer you seek:
Original Miata Thread: https://forum.miata.net/vb/showthread.php?t=618312

They cite either 3M window weld product available on Amazon here:

3M 08611 Window-Weld 5/16" x 15' Round Ribbon Sealer Kit -
3M 08620 Window-Weld 1/4" x 15' Round Ribbon Sealer Roll -

I have not replaced the barrier on any of my cars so I cannot give first hand experience. I am proliferating the information from a different forum because they already tackled this problem. Does this help any?

Cheers,
George

P.S. I dislike the text editor since its upgrade last month (or two)!

Yes you are most certainly right, at the peak would be a Toyota Hilux, an AK-47, a cockroach and a war in the Middle East.

However, if we’ve got th chance to improve a design, why not do so? And to your comment about what cars are using today, I’m not sure if you’ve been in many door panels of late, but I’ve seen more and more composite materials and a closer attention to sealing the panel as automakers seek to eliminate the need to upgrade factory stereos.

Cars these days have so many systems tied into the information displays that replacing their factory stereo becomes tricky and as such they’re making the stereo systems better and better.

To me, you’re there already right? Leave your mark, make an improvement.

Nick

something like an 04-09 Mazda 3, Rx8 and the 6's don't use one at all. these cars have a basically hollow door (no inner skin), with a flat (basically) panel that bolts in. the window regulator then bolts to this thing.

and of course the door panel is also plastic..

Dale, I know this may be a little too late to help you. But, for any folks stumbling upon this thread looking for the OEM sealant used to attach the polyethylene sheet to the inner door panel C.R. Laurence makes the stuff, its called
CRL7708 Windshield and Body Sealant.
It is a non-curing flow grade butyl in cartridges that remains tacky forever, it does not skin over or dry out ever. Just one caution, this stuff sticks to everything, your fingers, shoes, the carpeting, upholstery, and door panel. How do I know? Unknowingly, I got some on my fingers and for 10 minutes, before I discovered it, everything I touched had the sticky gooey stuff on it. The only way to remove it is with mineral spirits, amazingly acetone has no effect on it. So practice first, wear disposable gloves, and remove the gloves as soon as you are done applying it and don't let it touch anything else!
https://cimg7.ibsrv.net/gimg/www.rx7...e1e9477ee2.jpg