Masking hardtop foam during installation

[Tomnistuff]

Since the hardtop flows air through the cabin as a function of the ventilation system when the windiws are closed, shouldn't one mask the foam where the oval holes are in the inner roof braces so as not to completely block off the air flow with contact cement or spray-on glue?

I did not do that, so I think I will cut out the foam in the holes and "patch" them with fresh foam glued only around the edges.

Any comments?

Opinions welcome.

Tom Kizer

[Pawel66]

I would have thought that with windows closed the source of air for cabin ventilation is the vent system for windshield, dash and under dash areas...

[Tomnistuff]

What I meant is that with the windows up the air comes in through the cowl scoop to the heater or air conditioning or dash vents but there is only one exit, ignoring leakage.  That is, as far as I know, through the perforated headliner, through the foam, and through the roof inner panel holes to the rear roof vent at the top of the rear window.

If the foam is plugged with adhesive on the upper side where it is glued to the roof, the exit flow is likely pretty badly restricted for either heat or air conditioning.

I'm just suggesting that reducing the restriction of the foam at the inner roof panel holes would perhaps help the air flow, summer or winter, when the windows are closed.

I am wondering if it is even necessary to close the holes with foam, since their surface area is so small compared to the foam covered metal of the inner roof.

The whole issue may be irrelevant, since most of our cars are not even driven with the hardtop on in the Summer, or at all in the Winter.

Tom Kizer

[Tomnistuff]

Here's the picture that goes with the air flow.  From the Mercedes introduction video.

[Tomnistuff]

Maybe I should ask the question a different way.  Has anyone ever seen an intact original foam hardtop linsulation that would show whether the foam glued to the hardtop was cut out where the holes in the inner braces are?  I guess it would have to be someone who saw hardtops being made in the factory.  Gernold maybe?
Tom Kizer.

[66andBlue]

Tom,
I believe the foam covered the elongated holes along the sides but I let you be the judge.
When I restored my hardtop I used a closed-cell foam for sound and temperature control and cut out the holes.

[Sead]

Holes on l +r were covered by insulation material.
Far rear end must not be covered! to allow air flow.
See pictures. Clearly visible are signs of cutter where foam has beeb cut off to free up 3 spots.

[66andBlue]

Air flows also along the channels on left and right and not only through the center openings in the rear.
The original was course open cell foam that let the air through similar to what is now in some air filters used in heating and cooling applications.

[Tomnistuff]

Fascinating!  I opened the foam that covered the three holes on each side at the top of the quarter windows, based on your observations, Alfred.  And I opened a "sort of half circle" in the foam at the rear of the three center panels, based on your observations, Sead.  See the photo.

I then probed, and probed, and probed with a wire in all the holes and in the vent slots across the top of the rear window, and can find no access between the holes and vent slots.  That is not to say there is not an access, but I can't find it.  It must be there because I can find no other explanation for the holes on the inside, the separation between the inner and outer panels at the inside rear, the slots across the back on the outside above the rear window or especially the illustration of air flow in the Mercedes 230SL Introduction Video.

At some point, one has to trust that Mercedes did all of that for our own well being.  I do.  So I'm going to get on with the reassembly of my hardtop and trust the Mercedes engineers.

Thank you all for your previously validated opinions, logical observations and, in my opinion, good judgements.  Isn't that pink just so feminine?

Tom Kizer

[66andBlue]

Tom,
you should give it another try to find the vent openings. Probe with a flexible wire from the out side. Perhaps the attached photo might help.
Also I would cut more than 3 holes along the sides and also down the end pillar. You want as much air flow as possible. Perhaps enlarge the slits in the center a bit more.
Lastly, I think the strips that keep the headliner lifted up should be a bit more bowed.
Just some suggestions.

[cfm65@me.com]

Hi Tom,
I am about to start fitting the hood lining in my hard top. I did one a few decades back and have done a few on other cars as well.
Could you please let me know the thickness of the foam you are using?
Regards
Chris
Cape Town

[Tomnistuff]

Hi Chris,
My foam is called sewing foam, which means it has a nylon fabric bonded to one side for reinforcement so that when sewn in a garment, it won't move around and bunch up.  That's the way I understand it.  It is 1/4 inch thick (maybe a bit too thick).  I do not know the correct thickness of the original foam.  I bought it from a Canadian fabric supplier.  I did not buy the foam from a Mercedes parts supplier because I wanted one piece and those I found were expensive and slightly too narrow in width.  In retrospect, that was not achieved anyway.  Mine may be too thick because it was necessary that I cut away the foam in the area of the rods to allow the headliner "pockets" to slide more freely on the rods when stretching the headliner (front to rear).
This is my first, and last, Pagoda restoration so I am a restoration novice and by no means knowledgeable on the subject.
Good Luck
Tom

[cfm65@me.com]

Thanks Tom,
Much appreciated.
Regards
Chris
Cape Town

[Tomnistuff]

Tom,
you should give it another try to find the vent openings. Probe with a flexible wire from the out side. Perhaps the attached photo might help.
Also I would cut more than 3 holes along the sides and also down the end pillar. You want as much air flow as possible. Perhaps enlarge the slits in the center a bit more.
Lastly, I think the strips that keep the headliner lifted up should be a bit more bowed.
Just some suggestions.

Hi Alfred,
I was delayed answering because I took your advice.  The attached photo shows the added holes, and although difficult to detect, the wider slots to the center rear.  I found the passages you were talking about at the lower corners of the C-pillars and also from all the rod clip punched holes to the center rear slots.  I tried faithfully, but was unable to find any passages leading to the outside slots above the rear glass (back-light was what we called it in the U.S. auto industry).  I'm reasonably sure they are there, but I just couldn't find them, probably because I've never seen the inner sheet metal being welded to make the hardtop.
Anyway,  If the passages from the center to the top center vents are there, I have accommodated them.
Thanks for your help.
Tom Kizer 

[66andBlue]

Looking good, Tom. 👍
Before going further punch the holes into the foam for the two grab handles screws. You want to prevent the possibility that the foam starts twisting when you put the screws in later.

[Tomnistuff]

Thanks, Alfred.  The screw cutouts there, but the photo angle doesn't let you see them.  I've got the Heritage headliner.  it's beautiful.  I'm supposed to receive the rear window seal tomorrow.  I'm going to take my time.  Thanks for everyone's help and guidance.  The black plastic strips to support the headliner are now so tight to install that they bow naturally upward to the shape of the hardtop after installation.  They will be a little bit hard to install, but they are for another 50 years.

Tom

[66andBlue]

Tom,
these "black plastic strips" need to go through a sleeve on the headliner.
In addition to these sleeves an OEM headliner also had a gauze fabric sown in that was glued down to help stretching the headliner into a wrinkle-free shape. Later aftermarket (and I believe also those sold by MB now) no longer have the gauze.
What does the Heritage headliner have?

[Tomnistuff]

Hi Alfred,

I was aware of the cardboard "tabs".  Mine were garbage so I cut them out from a heavy plastic container.  I assume, when you said to make them bowed, that you meant, "make them longer so they are bowed when installed and are in compression when supporting the headliner like an arch.

My Heritage headliner does NOT have the gauze material for gluing like the one in your photo.

Although I am reluctant to cut on the headliner rod sleeves, I expect that I must "trim" the rod sleeves to fit the rod lengths, especially in the corner where the outside "short" rods meet the rear cross-rod.  I also assume that to ensure that the sleeves can slide on the rods during stretching and gluing, I will have to cut rod access notches in the sleeves so that the stamped rod-retainer hooks on the hardtop can "access" and support the rods without restricting the sliding of the sleeves on the rods.  At least that's what everyone does in all of the headliner installation videos that I have watched.

If I am unclear in my above assumptions, or have "missed" something please let me know.

Thanks,

Tom Kizer 

[66andBlue]

Yes, you need to cut the ends of the rod sleeves; miter cut at the corners and the front-back sleeves just before they touch the rear cross-rod. For the rod retainer hooks/tabs cut a slit parallel to the rod and long enough to push the tab through. Don't bend them too often they break easily!
I mailed you a very large photo that might help a bit.
Just to be sure, check the width and length of your headliner. Some aftermarket sellers don't have correct templates and the dimensions can be wrong as you can see in the attached photo, in addition to sloppy sewing. 

[Tomnistuff]

Hi Alfred,
You were right about the razor slots parallel with the rods.  My original one (which I saved when I took it off) has the same thing.  I was afraid if the clips grabbed the sleeve, then I would not be able to stretch the headliner enough - wrong.  I did a trial fit with the rods and headliner and everything stretches beautifully.  I'm not far from starting the final installation.  Even the black plastic cardboard replacements work nicely.  After fitting the headliner to the rods and the rods to the hardtop clips, I gave a light tap to each clip so that during final assembly and stretching, the rods don't pop out of the clips.

It's time for me to quit for the day.
All the evidence tells me that this is the first time the headliner has been changed on mine.  I've had it since 1987 (it was 21 years old when I bought it), and I've had it for 33 years.  By the way, there was no trace of gauze on the original headliner either.
Tom Kizer