Under carpet insulation

[280sl1968]

To what extent were the floors of factory original cars insulated with sound dampening or heat insulation material?

The cars I have looked at seem to have insulation in the front footwell area, but elswhere it is just carpet laid directly on the floor. I have seen a few aftermarket solutions, but don't know the extent to which the added thickness causes problems with new carpet fitment.

Road noise and heat isn't really a concern, but if I ever come to replace the carpet in I'd probably want to install some kind of underlay if that is what was done originally. My interest is early 280SL, but any general info would be good.

Thanks

David

[49er]

My 280 SL has only  jute pads  under the mats. I purchased a set of  GAHH mats for everyday use and they had a foam backing but still fit reasonably well over the Jute (after cutting the "notch" in the passenger side mat).

John

[280sl1968]

If you ever have the chance to post a picture of the jute pads, I'd be very interested to see what MB installed originally.

When you say you have put a set of GAHH mats in for daily use, is that so that you can take the originals out for safekeeping?

In the rest of your car is it simply original carpet adhered to the floor?


David

[49er]

 Hello David,
 Here are couple of pictures of the original jute pad from the driver's side, the first taken from the top and the 2nd showing the waffle pattern on the bottom. The passenger side is nearly identical and the pads only cover the flat part of the floor, not the foot rest. My original mats are in good shape but the driver's foot pad is cracked and brittle. I keep them sealed in a large plastic bag for safe keeping. When I had work done on the car a few years back (shifter bushings) the original tunnel carpet was damaged. It had pretty well "glued" itself down to the tunnel and tore when pulled up from around the shift lever. I bought the tunnel carpet at that time and decided to get the floor mats as well  to try and blend the color (dark brown) with the original. The match was close but not exact. all the remaining carpet in the car is original and all glued down.

John

[280sl1968]

John

It is fascinating to see some of the original materials in these cars and so well preserved.

Given that you say the pads only covered the flat part of the floor and didn't extend up behind the pedals it might be reasonable to conclude that they were to prolong the life of the carpet in a 'high traffic' area of the car as opposed to serving a primary function of being either a sound or heat insulation pad.

I have been tempted to buy a roll of foil backed insulation foam being sold by SL parts suppliers for the purpose of reducing road noise and heat in the car, but was concerned that the additional thickness might cause problems with fit of a new carpet set.

Given what I've seen and heard here, I might just limit it to the footwell floor if that is what was originally intended.

Thanks

David

[66andBlue]

Hi John,
are these pads on bare metal or do you have the tar/bitumen insulation over the bare metal floor?
On my 230SL these pads are on top of the bitumen layer.

[49er]

Hello Alfred,
 They are over a tar/bitumen surface and that is why there is some discoloration in the pads (from the tar) even though the surface was painted body color

John

[66andBlue]

Thanks John.
Quite interesting that they painted this bitumen layer!
That must have required an additional trip to the paint booth after these mats were melted/glued down.

[49er]

 This is probably the ugliest picture I have ever posted but after nearly 45 years of being stepped on I guess it isn't too bad It would be interesting to know if the body was first painted, these "tar/bitumen" pads glued down and then repainted. Seems like an unnecessary process.

John

[280sl1968]

Is that firewall pad material in the area behind the pedals?


david

[49er]

Is that firewall pad material in the area behind the pedals?

Yes

[66andBlue]

... and it is still available!

[280sl1968]

Thanks Alfred, you pre-empted my next question there.

Is it a pre cut MB part or would I need to buy the material and cut to fit? If not MB, who supplies it?



Thanks


David

[66andBlue]

David,
pre-cut diamond pattern material using actual  MB spec drawing for precise fit.  Here are the details to read up on: http://www.sl113.org/forums/index.php?topic=15615.0
I'll send you an email with ordering details.

[capcgn]

Dear John,

how thick is the original jute pad in mm ?  Is it like kokofibre or mor jute ? Thanks

Andreas

[49er]

Hello Andreas,
 The pad measures approximately 10mm in thickness and is jute.

john

[capcgn]

thank you.

[Tom Colitt]

John

One of my favorite subjects  ....

I'm quite sure the bitumen was in place when the cars were painted. What makes you sure that there is paint under the bitumen? Only on 1970 and 1971 cars, was there an additional aluminum/ fiberglass insulation on top of that....

[66andBlue]

Hi Tom,
the inverse question to you would be "how do you know the insulation was put down before the car went to through the paint station"?  
Or in other words, what was installed inside the cabin before painting?
On my 230SL the bitumen insulation was added after painting and never painted again.

[Tom Colitt]

Hi Alfred

You kind of answered your own question. If it was painted it was installed in the car before it was painted, as on 280SLs, if not it was installed afterwards, as it apparently was on your 230SL...

Unless, I misunderstood your question and you think that paint on the Bitumen doesn't prove that is was painted together with John's car. In that case, I will bet you that you won't find paint under his bitumen mats, only primer... :-)

[Tomnistuff]

While, as an ex-automotive engineer, I find the "paint-before-vs-after-bitumen-installlation" discussion fascinating, I would really like to know where one can buy real jute padding locally.   What I mean is, what kind of shops sell it?  If I buy it from the Online Fabric Store or Stock Interiors, in the U.S., while the product is not expensive, the shipping to Canada is several times the price of the padding.  I can't find carpet stores here that still use jute for carpet padding.  They all use some sort of foam now.  The businesses that still sell it, automotive upholstery and carpet supply places, seem to be scarcer than hens' teeth here in Canada.

At least the bitumen is easy.  It's available here from building supply stores or lumber yards and one version is called RESISTO ALUMINUM WATERPROOFING MEMBRANE.  Their advertising says, "it is a multipurpose selfadhesive membrane composed of SBS modified bitumen, protected by an aluminum surface film. It is perfect for flashing and repairs, as well as other small maintenance jobs around the home, cottage or farm. (50cm x 10m). (20" x 33')."  Here in Canada, it's $77 per roll.  I used a version without the aluminum for another restoration and it worked well.  Even better, this version has an aluminum film (that does not peel off) on one side and a plastic film on the other side that peels off so it can stick to anything instantly and permanently.

I plan to stick aluminum cooking foil to that side also so it doesn't stick to the car forever and ever, and I'll lay the four pieces of jute padding over the bitumen sandwich.  In that area, It will be: floor - foil - bitumen - foil - jute - carpet.

In the firewall interior area, I think I'll stick the firewall pad material to the sticky side of the bitumen and glue the bitumen/firewall pad assembly to the car with the aluminum side against the sheet metal.   It will be: floor - foil - bitumen - firewall pad material - carpet.  I hope that is a correct way to insulate the car for future air conditioning.  Any opinions?

Now to the fascinating discussion.

To me, logic says, "Since the bitumen is not ever supposed to be visible to the customer and, the last I heard, bitumen doesn't rust, then there is no reason to take the extra effort to paint the bitumen if it is installed after the car is painted."  Additionally, there is no reason to paint the car before installing the bitumen, since bitumen will protect the sheet metal floor better than paint anyway.  So, I would postulate that the bitumen is probably installed wherever on the line that it is convenient to install, without regard to whether it is before or after paint.

I would think that a sure bet would be to say, "If there is paint on the bitumen, then there is no paint under the bitumen, and if there is no paint on the bitumen, then there is paint under the bitumen."

Maybe someone will be willing to take several cars apart to verify - fat chance!  Not me!

If anyone has a idea where to find jute padding (locally), similar to the idea of using roofing material for car noise damping (or dampening, depending on which dictionary you prefer), please publish it here.  Does anyone know for what else it might be used?  I'm getting desperate to avoid paying $50,000 to restore my car and another $100,000 shipping and customs brokerage costs (I tend to exaggerate, but not much).


Tom Kizer
Québec

[49er]

All I can say is the tar/bitumen is really bonded to the floor's surface and would be impossible to lift up a corner to see if there is paint underneath. My belief, in looking at the uniformity of the paint application to my floor is that the insulation was applied before painting the body color. Perhaps after the primer coat? Alfred? Achim?

John

[Bonnyboy]

My 1969 280sl had the following on the floor - Painted metal, glued bitumen, foil over fibreglass and then carpet

However where the bitumen wasn't covered by the carpetting over foil over fibreglass, the bitumen was sprayed body colour (up under the dash)

That suggests to me that the bitumen was placed in two distinct processes - the flooring put in after the interior was painted.  The workers knew where the carpetting would go and would have placed the bitumen / foil over fibreglass and carpet in a single sequence.  

[badali]

Here is the original pad that is still in my 230 SL.

[49er]

Here is the original pad that is still in my 230 SL.

 Looks good to me:-) Just curious as to what lies under the pad.

John