Author Topic: 450SEL Roof Sound deadoning  (Read 524 times)

Mergyver

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450SEL Roof Sound deadoning
« on: 12 October 2018, 05:56 AM »
Hi guys, one of my main focuses now is reducing cabin noise in my SEL. So far I have done the following;

Tightened all fasteners on heat shields under the car (many were loose)

Replaced the Muffler (huge rust hole)

Replaced worn, and installed missing, rubber exhaust mount donuts

Replaced sub frame mounts

Installed missing under hood insulation blanket

With all this I think I am still hearing more road/wind noise than I would have expected.

Here is the question... when I was fixing the sunroof (it would not open) one of the issues that I found was that a piece of what appeared to be sound deadening insulation was jammed behind the sunroof which stopped it from opening more than a couple of inches. So I pulled it out piece by piece.  I assumed a prior owner had put it up in there for some reason. Recently I was browsing through a Mercedes parts site and I saw a sheet of "roof sound deadening material" listed for my SEL. Has anyone had experience with this? Did the car come with material glued to the roof? Does it make much of a difference? How tough is it to install, do I need to drop the head liner?

Also, anyone have any other ideas as to where I should be looking to reduce noise? How about door seals, do they make much of a difference?
1974 450SEL
1979 300SD
1989 560SL
2005 E320 CDI Recently deceased

floyd111

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Re: 450SEL Roof Sound deadoning
« Reply #1 on: 12 October 2018, 07:49 AM »
You started correctly, trying to solve it by tightening everything loose, but from there on, things will more complicated. Are the doors exactly in position, or are they out of alignment? If so, spending big bucks on new seals may be wasted. But, I am a fanatic about road noise reduction, and I would change the seals AND check the doors, haha! After that, I would have a go at re-insulating the firewall with GTmat, as well as the bonnet, the doors, the floors. I can't judge your sunroof issues, but I doubt that besides the sunroof, you'll have much noise coming from the roof. Heat insulation mats are more suitable there, rather than sound deadening material. GTmat does have combi-mats for roofs, but they aren't cheap!
Last thing I can suggest as a non-mechanic is to check your suspension-related rubbers under the car, as well as your engine mounts. Average-looking rubbers may already be at the point of passing on road noise to the cabin, even though they look like they may still be OK.

On that note, I would like to know how bad these vinyl cabin parts shake and tremble in real life. Do they? Are there tricks to avoid that from happening when assembling a car?

ptashek

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Re: 450SEL Roof Sound deadoning
« Reply #2 on: 12 October 2018, 08:04 AM »
Refreshing the deadening matt in door  panels does help a little too. There's two more, one each side, on the inner rear wing surface.

The roof itself has no sound proofing to speak of from factory. Some 10mm felt pad on the sunroof pan, which is more for show than function.

Another place is the rear bench, also a thick felt pad which isn't great and tends to acquire all kinds of bad smells over the years.

I've replaced all of these with a dynamat-like sound deadening, then soundproofing foam on top  of that where it made sense.  I haven't covered the entire roof with it though as it'd be to heavy (these mats weigh a lot!).

Even with the much improved materials replacing factory stuff, the car isn't that much quieter anyway.

That's how most of my car is done:






« Last Edit: 12 October 2018, 10:16 AM by ptashek »
1993 "Pearl Blue" W124 280TE
1979 "Icon Gold" W116 450SE (history, resto)
1977 "Milan Brown" W116 350SE (parted out)

daantjie

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Re: 450SEL Roof Sound deadoning
« Reply #3 on: 12 October 2018, 08:39 AM »
One thing we have to realize is that these are 40 year old cars and to expect noise levels to compare to modern cars is folly.  Not saying it's pointless to improve it just that you might want to taper your expectations ;)
Daniel
1977 450 SEL 6.9 - Astralsilber

floyd111

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Re: 450SEL Roof Sound deadoning
« Reply #4 on: 12 October 2018, 03:02 PM »
Wow, that seems almost impossible a story! That much mat did not turn that car into a Rolls of some sorts? I am confident it was heavy, but what brand did you use? Normally, it will turn a Jeep Willy into an old Ford Escape, or an Escape into a bearable car. Are you sure you're not just hearing the engine rev?

Mergyver

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Re: 450SEL Roof Sound deadoning
« Reply #5 on: 12 October 2018, 03:19 PM »
Wow, ptashek, that is one heck of a job you did there. I have to believe you have a pretty quite car at this point. must be nice.
1974 450SEL
1979 300SD
1989 560SL
2005 E320 CDI Recently deceased

Mergyver

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Re: 450SEL Roof Sound deadoning
« Reply #6 on: 12 October 2018, 03:26 PM »
I just got done taking out the back seat and package shelf (Hat rack?). I am looking for rattles and the source of a leak that seems to fill up my rear passenger foot wells.

I found the source of some of the noise. The car is missing the medical kit compartment. this has left a large open access panel into the space between the back seat and the fuel tank. There was just a piece of thin wood paneling over it.

The other problem is that the vacuum reservoir behind the back seat is being held in with just a coupple of zip ties. So it has been banging around back there. Anyone know where I can get the vacuum reservoir bracket or the medical kit compartment?
1974 450SEL
1979 300SD
1989 560SL
2005 E320 CDI Recently deceased

floyd111

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Re: 450SEL Roof Sound deadoning
« Reply #7 on: 12 October 2018, 04:34 PM »
You'll need to find a used hat shelf, but why not consider placing a JL Audio slim bass speaker in there? It's the only spot in the car to fit one, without cutting into the metal.

Mergyver

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Re: 450SEL Roof Sound deadoning
« Reply #8 on: 12 October 2018, 08:35 PM »
Not a bad idea Floyd. I will take a look.
1974 450SEL
1979 300SD
1989 560SL
2005 E320 CDI Recently deceased

ptashek

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Re: 450SEL Roof Sound deadoning
« Reply #9 on: 13 October 2018, 10:01 AM »
Wow, that seems almost impossible a story! That much mat did not turn that car into a Rolls of some sorts? I am confident it was heavy, but what brand did you use?

StP Silver 1.8mm (3.4kg/m^2) for vibration damping, then K6s either 6mm or 9mm closed cell foam for sound proofing.
The only thing the butyl mat does is resonance frequency shifting, the sound proofing is done by the K6s and that drops the noise by 40dB, best case, per manufacturer spec.

You have to remember that most of the road noise is getting through the glass panels, and roof, and it somewhat cancels out all these sound proofing efforts lower in the chassis.

I mean the car is quiet, but it's not drastically quieter than with the factory stuff.
Compared to my W124 or daily Toyota, there's no contest. Both are vastly quieter.

Hardly a scientific test, but these two videos will give you an idea of how much of a difference there was.

pre-resto
https://www.youtube.com/watch?v=c8pqaOCKEG0

post-resto
https://www.youtube.com/watch?v=voSgTwfES_A

The camera in the second video is windshield mounted and has a more sensitive mic.
 
1993 "Pearl Blue" W124 280TE
1979 "Icon Gold" W116 450SE (history, resto)
1977 "Milan Brown" W116 350SE (parted out)

ptashek

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Re: 450SEL Roof Sound deadoning
« Reply #10 on: 13 October 2018, 10:07 AM »
leak that seems to fill up my rear passenger foot wells

Most common reasons:
- rust holes in the top corner under the hood, where the hood cable enters the chassis, or the same spot on the other side
- blocked sunroof drains.
1993 "Pearl Blue" W124 280TE
1979 "Icon Gold" W116 450SE (history, resto)
1977 "Milan Brown" W116 350SE (parted out)

ekipe

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Re: 450SEL Roof Sound deadoning
« Reply #11 on: 27 October 2018, 05:36 AM »
Before any modifications I would check and replace if possible all rubbers and seals from doors and glazing. Also would be wise to check subframe bushings and engine mounts.

nathan

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Re: 450SEL Roof Sound deadoning
« Reply #12 on: 27 October 2018, 05:48 AM »
nice work PT

Mercgyver, I was beaten to it by ekipe, the door rubber seals.  the doors let in a bucketload of wind noise if old. be sure to check these as I would think the most likely culprit as a perishable item.
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Mergyver

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Re: 450SEL Roof Sound deadoning
« Reply #13 on: 06 November 2018, 06:19 PM »
Thanks guys. I replaced the sub frame mounts. That made a huge difference. I am thinking my door seals are so dried out that replacing them would make a huge difference. I can't wait to find out.
1974 450SEL
1979 300SD
1989 560SL
2005 E320 CDI Recently deceased