Adding extra sound deadening to doors

[darek_u]

I'm thinking about adding an extra layer of sound deadening to all 4 doors. Is it possible to apply Dynamat to outer sheet metal of the doors without removing window mechanism, door latches, harness etc? I haven't removed the door cards yet on this car, just gathering information prior to kicking off the project. Any input will be much appreciated.

 

[gerryvz]

I'm sure it's possible to add it, but the access will be somewhat limited through the hole in the door to get coverage. I think you would have to have the window in the "up" position to be able to do it.

You are looking at this type of opening for each door:





Not a ton of room to place the pads, but workable. It will be tighter inside of your doors, as opposed to the doors in these photos, because of the window motor/regulator, glass, lock and latch mechanism, etc.

 

[darek_u]

Many thanks Gerry. Front door will be a problem... With window regulator in place nearly impossible. Well, I guess it will be a perfect time to overhaul it and grease. Rears should be ok, even with all parts in place.

 

[maw1124]

When I asked about that I almost got laughed out of the shop... no one wanted to touch it... I guess if you're DIY maybe that's a good use of time and effort... maybe... I never felt the need for more sound deadening in this car... the windows do a LOT and the doors are plenty hefty, as you see.

maw

 

[gerryvz]

It's definitely a job that would be more of a labor of love, rather than something that is really needed. In my opinion, the ROI for doing this would be very, very low, and only if you were doing a complete refirb (removing everything from the doors for rust repair, total repaint, nuts-and-bolts restoration, etc.). Otherwise, as @maw1124 says, there is not a pressing need for more sound deadening in the car.

 

[gsxr]

Remember that you DO NOT need to cover anywhere near 100% of the sheet metal to get sound reduction with Dynamat or equivalent products. Usually around 10-20% is plenty. They don't like to tell you this, because they want to sell more product. Years Decades ago, some car stereo shops had demonstration displays to show this. You can make your own... get 2 identical tin cans (i.e., tuna can, cat food can) and apply a 1/2" (1cm) square bit of Dynamat to one. Now tap on each with your finger, a screwdriver, whatever. The difference in resonance is amazing, even with a tiny amount of Dynamat.

And yes, you can apply inside the doors without removing any wiring or internal hardware. If the factory sound damping material is peeling off the outer skin, you can just remove it and replace with Dynamat.

 

[darek_u]

I know that W124 has a good sound deadening from the factory, especially floor area where sound proofing material is as thick as 7 cm in places - hard to beat that. Anyway, there is still a room for improvement, especially in the door area. I've already added some material to the roof and it made a difference. I don't expect night and day but definitely there will be an improvement. I applied Dynamat extreme to my 944 doors, floor and rear bench and the difference is significant. It is a whole different animal but I believe i can get similar results in 500E.

 

[gsxr]

I agree there is room for improvement, and I've added Dynamat in a couple of my 124's. My point was, you don't need anywhere near 100% coverage, and there's no need to remove window regulators or door lock/latch mechanisms. Just remove the door panel and vapor barrier, and replace the vapor barrier if damaged. You can apply a healthy layer over bare metal under & behind the rear seats and rear fender well areas.

 

[PJmak]

I agree there is room for improvement, and I've added Dynamat in a couple of my 124's. My point was, you don't need anywhere near 100% coverage, and there's no need to remove window regulators or door lock/latch mechanisms. Just remove the door panel and vapor barrier, and replace the vapor barrier if damaged. You can apply a healthy layer over bare metal under & behind the rear seats and rear fender well areas.

View attachment 117082 View attachment 117085 View attachment 117086

Any noticeable improvements?

 

[gsxr]

Any noticeable improvements?

Yes, but it's a modest improvement, not drastic. If you are installing a high-end stereo system, I'd recommend it, as anything you do to reduce exterior noise will improve audio quality. Otherwise, I'd just add small amounts where convenient. This was on the 124 chassis, I'm not sure how the 202 or 210 would respond to similar treatment.

 

[Jlaa]

Like @gsxr indicates, you don't need to cover 100% of the inside of the exterior skin of the doors to yield a big effect. Just apply where you can reach. It makes a big big big difference when knocking the doors with your knuckle. I'm not sure if it make that big of a difference in reducing the noise floor, but in terms of reducing the probability of metal vibration, it does a good job.

 

[sheward]

I added my own insulation to the doors as well. I used pieces about 6 x 20 and was able to fit them with the upper edge at the side intrusion bar without removing the window regulators quite easily. I thought this might make the closing sound of the doors even nicer if nothing else.

drew

 

[a777fan]

On the noise front... the only area of complaint I have ever had in the 124 is the errant 'wet tire' noise I get from the rear end when its raining. By this, I mean the noise present from the tires when rolling over wet pavement at speed. I'm not doing a very good job explaining this, but its definitely more noticeable in the 124 than I would have expected.

Being in Seattle, I deal with this a lot, so I am wondering if anyone else has ever noticed... or if I am just nuts.

 

[LWB250]

It's all about adding mass to the component. The more mass, the lower it's resonant frequency. Doesn't really matter where on the door, for example.

Dan

 

[kegmankipp]

I used a case of Dynamat Extreme on all doors over the vapor layer, a couple 6x10” pieces in each door on the outer skin, parts of the floor in front, inside car on fender wells front and rear , and under the rear seats top and back.

You can get a case of 10 -4.33 square foot sheets cheap from Amazon for around $175 delivered.

I measured a14 db drop in road noise at 65 mph. Worth every penny and an afternoon.

Pure Luxury

 

[szvook]

This sounds like a weight gaining course for 124’s suffering from anorexia...

 

[darek_u]

I measured a14 db drop in road noise at 65 mph. Worth every penny and an afternoon.

This is a HUGE difference. I definitely want to do doors, as much are as I can but without going crazy, and sheet metal under rear seat including top of wheel arches. I don't think I'll add anything to the floor pan as I consider it well done from the factory. Anyway, if I have some sheets left I can apply some there as well. Like I said before I have roof done, as I have A pillars covers off I mad add some small strips on top of them as well, I heard that it helps with wind noise at highway speeds.

 

[darek_u]

Just to wrap up this thread... I completed this task, obviously it turned from simple "add some soundproofing material" to complex "while you are in there" stuff... Cleaning, fixing, replacing, painting, preserving, polishing - you know what I mean. Anyway, rear doors are relatively simple to do, front ones are more tricky due to window regulator in the way. I managed to cover around 90% of the area without any major issues.
I can report that there is a major improvement. It's not like 0 - 1 change from usual noise to Maybach like silence but definitely an improvement. My best guess would be 40-50% less noise, in my opinion - it was definitely worth of doing. I used 2.5mm thick butyl (not sure if it is a correct English word?) mats for doors and rear bench area, thick butyl-aluminum-butyl-foam (12mm thick all together) material for rear wheel arches at rear bench area. I also put 6mm foam material on the inside of the door cards.

 

[darek_u]

BTW what is this sensor (?) under comfort module? Is it for brake system? I remember reading something about newer cars having a sensor for distributing braking force between the axles. My car is Euro '92 but with late LH and other late model goodies.

 

[gerryvz]

Hi @darek_u,

That yellow module is the control module for the heated seats. On the W124, it's found directly underneath the comfort/convenience module, correct, on the driver's side under the rear seat bottom.

 

[darek_u]

Thank you Gerry. I can see Mercedes made it complicated... I would expect a simple relay with timer, not a module with thick wire harness, unless it IS a simple relay in a fancy box

 

[gerryvz]

I think this relay required some extra engineering because of the voltages involved to power the seat heaters.

 

[gsxr]

The relay is required because there is a high/low setting for the heaters, AND also a timer function with different time limits for high and low heat. It's not a simple on/off function.

 

[500AMM]

On the noise front... the only area of complaint I have ever had in the 124 is the errant 'wet tire' noise I get from the rear end when its raining. By this, I mean the noise present from the tires when rolling over wet pavement at speed. I'm not doing a very good job explaining this, but its definitely more noticeable in the 124 than I would have expected.

Being in Seattle, I deal with this a lot, so I am wondering if anyone else has ever noticed... or if I am just nuts.

Exactly what I find as the most dominating as well - wheel noise. Especially from rear, sounds like it blows straight through the sides of the rear backrest. In front it sounds like the noise comes through each end of the dashboard. If I ever take out the dashboard I will pack the cavities behind the dashboard + the tiny cavity in the chassis behind the footwell side panelling, really good noise transmitters with close to zero barriers IMO. Is anyone aware of some sort of noise reducing expanding spray foam for filling inaccessible cavities?

 

[a777fan]

Exactly what I find as the most dominating as well - wheel noise. Especially from rear, sounds like it blows straight through the sides of the rear backrest. In front it sounds like the noise comes through each end of the dashboard. If I ever take out the dashboard I will pack the cavities behind the dashboard + the tiny cavity in the chassis behind the footwell side panelling, really good noise transmitters with close to zero barriers IMO. Is anyone aware of some sort of noise reducing expanding spray foam for filling inaccessible cavities?

Yes! Exactly this!

@darek_u any pre and post relevant improvements noted on this specific observation other than the reduction you have already shared?

 

[speedy300dturbo]

A lot of road noise comes in through the rear wheel wheels which basically transform the trunk into a large echo chamber. The noise then resonates up through the rear bulkhead into the passenger compartment.

Pull back the trunk liner panels and apply sound deadening to the wells and you'll notice a massive improvement. Newer cars have this area heavily insulated. The first picture shows a W210 with factory insulation on the rear wheel wells. The W211 (second picture) has a molded foam insulation piece.

 

[500AMM]

Very good points! And the best effect is from molded and bonded material to the metal, like the various sound deadening mats.
I once tried to reduce noise on an aging, small outboard and cladded the cowling entirely inside with a 15-20 mm compact foam, but with absolutely no effect. So it has to be high density, low frequency materials.

 

[darek_u]

@darek_u any pre and post relevant improvements noted on this specific observation other than the reduction you have already shared?

I know exactly what you are talking about - annoying sound of gravel and sand hitting the wheel arches. That's why I used different material, sandwich like and thick, in that area. There is no night and day difference, the sound is still noticeable but quieter and not so aggressive, just like you would turn the volume down from 5 to 3, maybe 3.5. I fully agree with what speedy300turbo says about covering the arches from the trunk side, this would definitely make a huge difference. I didn't do it because I'm anal about stock look, even behind the trunk liner... I couldn't already sleep well knowing that behind the rear bench my car doesn't look stock

 

[darek_u]

The snow is gone now and I had chance to drive 500E for a bit longer - I can't be more happy about the sound proofing I added. Now when the headliner is back in the car and the whole interior is completed I can fully appreciate how quiet it become. I strongly recommend adding some sound deadening material to the doors, roof and rear bech...

 

[Kyiv]

the only area of complaint I have ever had in the 124 is the errant 'wet tire' noise I get from the rear end when its raining. By this, I mean the noise present from the tires when rolling over wet pavement at speed

Oh yes. Sounds like the rear door or window is open. I still to this day check if the rear windows are indeed closed when it's raining