Door sound proofing

[Brennie]

I wonder if anyone can advise me on the subject of  car door sound deadening…I’ve just taken the door card off and found one black sticky pad stuck to the inside of the door skin( there was two but one had come unstuck and was lying crumpled up by the bottom of the door,looks like a botch job)…what should be there and what should I use now? Thank you 

[Pawel66]

There was one sheet of sound damping material. You may get an idea how it looked here:  https://www.sls-hh-shop.de/main/de/mercedes-230-280sl-w113/72-tuer/72-a-tuer

What you get today from a lot of vendors is just a piece of insulating mat (also at Mercedes).

I glued insulating mat and them foam all over the inner surface of the doors, as the sound when you close the door is important to me.

[Brennie]

Thank you….two layers? It didn’t interfere with the window mechanism?

[dirkbalter]

Originally, the doors has a single mat of insulation. The mat had arrays of holes to (supposedly) prevent the warping of the outer door skin during temperature changes.
You can buy the insulation mats from most supply places and cut them yourself or get pre-cut mats from various known vendors. 

[Pawel66]

Thank you….two layers? It didn’t interfere with the window mechanism?

Two layers is the usual dampening technology - harder and softer/thicker. No, it does not interfere with anything. The shifter is on the inside side, not the door skin side - on the door skin side, you have just glass and empty space.

[Brennie]

Thank you
Dampening and foam ordered…
My next job….

[dirkbalter]

Two layers is the usual dampening technology - harder and softer/thicker. No, it does not interfere with anything. The shifter is on the inside side, not the door skin side - on the door skin side, you have just glass and empty space.

Pawel,
Not familiar with the two layer theory. However, modern insulation mats, one can choose from, have multiple layers with an aluminum layer in-between for know reasons.
With the doors opening and closing, I would be careful when gluing to much stuff in the inside of the door. I would be afraid of the foam or other things coming loose and interfering with the mechanism in the long run.

[Jordan]

Brennie, here are two pictures of my door insulation, the second you can see the texture.  It was a single piece and I believe this is original.  The brown you see on the door facing is just old glue used to hold the plastic sheet in place.

[Pawel66]

Pawel,
Not familiar with the two layer theory. However, modern insulation mats, one can choose from, have multiple layers with an aluminum layer in-between for know reasons.
With the doors opening and closing, I would be careful when gluing to much stuff in the inside of the door. I would be afraid of the foam or other things coming loose and interfering with the mechanism in the long run.

Yes, certainly there are multilayer dampening mats, but the essence is the same: higher density for certain frequencies and lower density for others. Any material I read from several suppliers for several systems were all about that. You can achieve it via one mat with multiple layers or via several separate materials glued one on top of the other. Aluminum is there additionally where thermal insulation is important, e.g. over the exhaust.

Yes, the gluing needs to be done in such a way that these mats stay glued. I would have thought, that if part of the mat gets unglued, it may somehow get under the glass when the glass is raised. Same applies to the original one. It needs to be long enough piece that it is held by the rails on which the glass is sliding so that it does not lean inside to get under the glass. I have it for several years now, I have had doors opened for shifters overhaul - nothing wrong is happening there and the sound of the doors closing is just great.

[dirkbalter]

Marcus, I don't think yours are original (holes).

[Pawel66]

The drawings on parts lists do show holes in those panels.

[bogeyman]

On both my '69 an '70 they have the same panel as Marcus shows - no holes.

[Brennie]

So interesting… someone stuck two sticky slabs of dampener on my door.. one fell off and it lay crumpled on the bottom of the door… I’m guessing it’s all about clean surfaces for perfect adhesion..
Any other tips?
There is no plastic sheet there either… should I replace that while I have the card off? Any particular thickness or product recommended?

[Garry]

The whole idea of the dampening is to deaden the panel.  More is not necessarily better. Unlike a building wall where they try to block the sounds out, it is to change the frequency in the outer panel thus you see only a piece in the middle of the panel and not necessarily all over it so not too much as you may end up with a completely different problem.  As I said, more is not necessarily better and the whole panel does not get covered. I think they actually used left over pieces of the same material that the firewall pad was made from, same under the front of the footwell and also same pieces in the trunk.

You definitely need to put a plastic sheet over it as shown to stop the moisture and condensation getting on the door card.

[Jordan]

There is no plastic sheet there either… should I replace that while I have the card off? Any particular thickness or product recommended?

Anything thicker than a garbage bag.  You should be able to get a roll of plastic sheet (6mil) from your local hardware store, and then just cut it to shape.  The plastic sheet keeps the exterior water off the cardboard door panel (such as when it rains or you wash you car).

[Pawel66]

This foil was a clear foil, transparent. Similar protection was there behind the upholstery panels behind the, forgive my language, B pillar.

[Pawel66]

The whole idea of the dampening is to deaden the panel.  More is not necessarily better. Unlike a building wall where they try to block the sounds out, it is to change the frequency in the outer panel thus you see only a piece in the middle of the panel and not necessarily all over it so not too much as you may end up with a completely different problem.  As I said, more is not necessarily better and the whole panel does not get covered. I think they actually used left over pieces of the same material that the firewall pad was made from, same under the front of the footwell and also same pieces in the trunk.

I have the impression, actually, that it does dampen the sound better. Of course I may be biased.

[Garry]

Pawel.

The theory behind the piece of dampener material in the door was that the thin outer metal sheet of the door is excited by vibration and in effect becomes a loud speaker that will radiate vibration as noise into the car as the car is driven. Sometimes described as acoustic resonance. It is not to do with keeping any noise coming in from outside which is what the multilayered sound deadening on fixed surfaces is designed for.

If you have put lots of other sound deadener in there you may well end up with the same effect but you can also generate a water trap which then has other knock on effects on the inner door mechanisms of the door. It's a common mistake that restorers of older VW’s make and wonder why they have major rust problems several years later.

Garry

[Pawel66]

Thank  you. I understand working of the door skin as a speaker diaphragm in this case. That is why the stiff piece that factory installed is necessary there, I think. I also understand inside of the door is a very wet environment (that is why the outer foil is so important, we well as the drain holes at the bottom of the door). But the doors are aluminum and water, when it gets there stays a bit away from the shifter.

I think, that the inside of the door also works as a quite substantial resonator box and dampening its inside plays a role. It seems to me that, as the final effect may not be critical, it may be just a slight improvement, the materials availability and the cost may be factors why sound dampening made by factory was what it was. I cannot imagine thick felt there, for example.

[Garry]

Pawel,


Keeping the water away from the door card is pretty simple. We agree. The door skin and frame is aluminium we agree, but if you have taken a couple of doors apart you will see that the internal mechanisms can get quite rusty, particularly the glass holder base made from steel and several other items also steel.  Drain holes in the bottom of the doors often get blocked and water and thus the humidity level in the inner door gets quite high if the outside of the door gets any sun on it hence the rust of those parts. This is why it is important that door drains are kept clear.  If you introduce multi layered insulation that has the slightest possibility to capture or retain moisture you again increase the likelihood of increasing the rust rates on the components considerable.


Its always been a hot topic on VW Kombi forums and door skins have been known to rust through in a year and winder mechanisms fail due to inappropriate insulation in and on the inner doors and wall panels. As i said right at the start, more is not necessarily better.

[Pawel66]

Garry, thank you. I understood the warnings and everyone who reads it will benefit from them. I also have absolutely no intention to argue with them, as I think they are correct and useful.

It is a topic for close watch out.

As for my subjective view:I did apply insulation and I enjoy its effect. For the way my car is used - I think it is fine.

[Brennie]

Thank you all for your input and advice.. I think I’ll add the dampening squares and perhaps leave out the foam laver.. although I’m a sunny day driver, you never know when you’ll get caught in the rain…
Definitely going to replace the plastic sheet protector…
Any other tips whilst the door card is off?

[Garry]

Brennie,


One of the common problems with the mechanism is that the glass guides fixed to the lower edge of the glass get dislodged.  Whilst you have your doors all opened, it is worth checking that the guides are securly fixed to the glass as it is a bit of a pain having to remove it all again when your windows start to rattle and you realise a guide had detached and fallen to the bottom of the door.

[Pawel66]

I think it depends a bit on when were you there the last time and if you experience any issues with the doors, e.g. glass lifting, door locks working, rattling. What I looked at this winter when I opened the doors:
1. Are the guide jaws fitted to the glass (this is the most important point that Garry wrote about)
2. Certainly if the locks or shifters do not work properly - that requires attention
3. Condition of the plastic parts such as slides - are there rattles and if so, is it possible to eliminate them by slides adjustment (the slides are difficult to see without removing of the glass)
4. Slack in the window shifter - there are plastic parts too
5. Condition of the rubber rod holders and their plastic sleeves
6. Some cleaning and lubrication may be needed of the shifter mechanism and/or locks/rods
7. Any glass adjustments (but then you need to remember the order: door adjusted to body, glass to hard top, soft top to glass)
8. The foams in door handles might have deteriorated - you may want to replace them

More advanced, if you want to get into it, is the play or slack on window shifter - in my case it was the key reason I could not fully close the windows with top on. I had to replace the pins. Usually replacement of the plastic washers helps.

If you are gluing on the insulation/dampening - I do not know if the stiff plate is easy to fit there without dismantling the shifter. Soft mat is easy, but the rigid plate - I do not know. It is absolutely critical to de-grease the inner door skin surface well for the glue to hold.

As for the sound dampening, IMHO, nothing is going to get rusty -  when you are caught in the rain from time to time or wash your car from time to time - because of sound dampening mat in the door. I have it for some time now. Same rules, by the way, apply to overall sound dampening of the entire car.

[johnk]

I just finished my doors and the X-Mat I added didn’t seem to make much difference. What made a big difference was installing the new window whiskers at the top of the door as they hold the glass tightly when the door shuts. I was extremely fortunate though that Shvegel had an original MB set that he gave me. I understand the new ones are not that great.