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At rear bumper side. none
At the spare wheel well........none. ( yep I broke part of the big plastic screw holder , still works )
Ugly pattern hahahaha
I add a bit of aluminum tape, so that the bitumen joint layer gets protected. Again messy job
Bye bye ECO batttery. I decided to remove it to compensate for the 9KG of 3M 08840. I use 98% of 3 square meters or 6 of 50 cm x 50cm sheets.
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For those who never seen stiffener pads installed by MB on rear wheel well, here they are, those white lines.
Rear wheel arc shield is fleece like.
LEFFT REAR
FROM REAR VIEW TO SKY VIEW TO FRONT VIEW
Supposedly these white rubbery-bitumen like material prevents certain resonance and vibrations.
They are also found all over the trunk metal sheet, but painted white. BUT...none of it at the spare wheel well.
I shall report how this 3M blackie stuff performs.
I don't have after or before decibel reading.... I will know if I hear improvement. I know my car very well.
Bitumen is heavy, so this is good for low frequency range noise reduction. Also I am hoping less heat into trunk.
On long drive and surely with traffic jam, the trunk get hot because the last two mufflers are under the trunk.
Okey............ experimenting with front fender now.
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Side note : S-Class W220 front fender liner is the same as W212 rear one, the quiet felt/fleece type but with extra padding like W212 option 839, basically better stuff.
From Ebay . S-Class front fender liner
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01. I Sprayed rubberized undercoat to the plastic liner of front wheel.
At least if sand and pebbles on the road, less plastic-ky sound and more thud-thud like rear wheel liner.
This is the REAR portion of the liner, firewall side. Only the side facing the tire get this coating.
Damn, I suck at painting/spraying.... LOL
The FRONT portion. Also tire facing side.
02. Onlt the REAR portion of the liner, firewall side. Its firewall facing side gets 3mm and 10mm HVAC foam.
DUMB ME !!! Some area can not take any extra thickness added to it as installation is impossible, the male stud on car body can't get to its hole...LOL.
So me got to remove some....like 35% of total area ..DUGGGHHHH
03. I stiffened the wheel arc which is thin aluminum, with bitumen pad, different brand to 3M 08840 but same asphalt based.
I do not want 100% coverage, I fear corossion may come if these pads will trap water if 100% coverage.
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I am immitating the rear metal wheel well , where MB placed 4 lines of their white "glue" which is like bitumen too as stiffener. Find below.
This reduce drumming noise which comes from vibration of wide metal surface if without re-inforcement ribs.
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04. Last desperate measure. 10mm hvac insulation foam as medium frequency blocker to interior.
I did not glue the 10mm foam, just stuf it in there and use two nylon nuts to secure foam sheet, there already availble 2 male threaded studs.
I think the bitumen pad even not 100% coverage has done good for the thin alumimum fender skin W212 uses.
With simple Tap test , I can hear its difference between RIGHT side treated one and not yet treated one on the LEFT.
In real life the tin-can-ness resonance is now much reduced on that fender skin when I whack it harder.
I think this will aid a bit in terms of less transmitted vibration or droning overall, minor but bit by bit slowly I will find metal sheet I can treat, it may do good when all combined.
Which special glue does the 10mm foam call for? It looks the same as most closed cell foam, can just use the believe its 3m 90 spray glue just fine. Hit both surfaces let it tack up some then stick together and good to go.
The glue they reccomnded ( same brand as the HVAC foam ) and sold me is in a can and very jelly like, worse than PVC glue we use to do pipe. Black color too.
I have to admit the glue is awesome, but too messy for me.
did you do sound tests prior with dB meter so you can compare when done?
The AC stuff is better at heat transfer insulation then sound transfer insulation
I bet the dynamat is better at sound insulation then your AC stuff when glued to sheetmetal.
I did not measure anything, too lazy.
My ears are very good for anything coming out of and into my car, its better than a dB meter.... no kidding.
Yes, the HVAC EPDM closed cell foam is not as good as dynamat for sound control.
However, I am for super light weight and zero water holding foam.
I can't layer my plastc fender liner with butyl rubber or bitumen pad, too heavy.
I also will never fully coat my metal portion wheel well with any soundproofing which can cause rust long term, example dynamat 100% coverage, be it bitumen or butyl rubber.
I think I explained this some post up.
The glue they reccomnded ( same brand as the HVAC foam ) and sold me is in a can and very jelly like, worse than PVC glue we use to do pipe. Black color too.
I have to admit the glue is awesome, but too messy for me.
Yeah thats good stuff from what I recall. I believe over there you actually get the good glues that still contain the correct ingredients to work like they use to. In the states its harder now a days.
The 3m 90 I cant say is any easier to use unless ya can tape off what ya dont want glue on. Its a spray aresole type so if it blows anywhere it will stick to it lol. It will work really well with that foam. I used it alot when doing leatherwork when adhering the foam to metal, plastic, or leather. Also works to adhere the leather to the same but thats not really what your concerned with.
Anyhow good ideas and be worth noting for possible future endeavers.
Under carriage. MB made many stiffener "folds" on the floor for stifness purpose.
So I add very little asphalt/bitumen pad there.
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Suprise suprise, simply from having a few attachment points for fuel line and fuel vapor line, the LEFT under carriage floor panel produce less resonance when I knock it.
So I added only 2 strips of bitumen pad and not 3.
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FRONT LEFT WHEEL ARCH
Too bad there is no threaded male stud at LEFT wheel arc for me to use to secure the 10mm HVAC foam, so 3M alu tape is next choice.
Do you guys know that MB also occasionaly stuffed foam pads here and there without glueing ?
AT the trunk, see below :
This time the foam on the wheel liner facing tire, firewall side I dare not use the 10mm , only 3mm one and not 100% coverage anymore.
No point if installation is so difficult.
Rubberized undercoat
Engine Bay side. Rubberized undercoat only for the side facing the tire
I am still trying to source for small "impact" noises of components not sitting down properly or not secured properly.
The spare tire tool kit is another small noise source. You guys can test by hammering with your hand the spare tire itself and see what sound you get from the tool kit.
The jack if not screwed down well, its white nylon jack point can make noise, as it has hinges.
The tool kit tray itself make noise a bit from the jack jumping around on bad roads.
So I use foam and microfiber cloth to stuff here and there to make sure no more small rattle.
I even placed a thin beach towel ....LOL. Touch wood if I ever need to do spare tire change, at least I have a beach towel to use.
My car does not get the extra inner liner for spare wheel well, as some older moded of W212 without START-STOP do get.
This inner liner no 2. This inner liner also support at least 15cm the width ( marked green) of the unsupported floor no 1.
The total unsupported width of the floor no 1 is approx 90cm and that is very wide. So on bad roads, this floor no 1 jumps a tiny bit and made noise, very little.
The noise comes from the red zone I marked below :
I already have a light weight foam trunk floor "carpet", but it is very light weight and can't create a tightening/weight-down force for the vibration of the said red zone of floor 1.
Yes, one imagine the floor no 1 and the car itself are all fleece like material, should be quiet right ?
Well the middle part of the floor 1 is where resonance happen, too wide an area unsupported.
It is awesome, heavy and yada yada...........BUT, it has very STRONG rubbery smell !!!!! when re-open the trunk after 5 minutes....holly cow, what an irritating smell.
It shouldn't have smell as per data sheet. LIAR LIAR LIAR !!!!!
My intention with this MLV is cut it to fit 100% of the trunk floor shape.
So the MLV will become also a noise barrier and an even weight-down material for floor no 1 to no more make noise....well that is the plan.
I will sun dry and vent well the MLV hoping it will gas-off itself in a week or so..... I hope.
It is expensive at US$50 per square meter.
There are 2 more irritating noise source from the car and it will only be heard if the road is bad enough or when on a azz-hole designed rumble strip painted on the road.
Developed country rumble strips are at side of the road for sleepy driver going off course in a highway like those in USA.
Unless superb air suspension, my Bilstein B4 front and B6 rear is not designed for such frequency and the sudden 10-12mm thickness without nice sloping gradient 0mm to 12mm kind of rumble strip.
In the rain such rumble strip is VERY dangerous for motorbike and even cars without ABS when wet braking, they are very slippery.
Even simple zebra-cross paint at traffic light is slippery in the rain if one's car is decently high power.
Anyway, front bumper is the worse noise maker of all for such rumble strip or bad roads.
It is so plastic-ky and has so much flexible surface area for pedestrian protection, try hammering your front bumber with your palm and enjoy
the irritating noise it can generate.
Rear bumper not too bad, because not much hardware on it.
I someday need to find ways to get rid of such potential vibration/mild-rattling for bumpers without adding much weight or else the
tabs holding the bumpers will break from extra weight.
In the name of crumple zone, this is the El-Cheapo sound the front bumper can produce
So its been 5 months today, that I have aired it in open air but not under the sun.
So I tested the MLV this few days.
I have not cut it to a nice trunk floor space shape yet, will do soon as I have decided, it is worth the road/tire noise reduction quality.
Hear my talking/voice and the signal light clicker as "ambient" noise.
I was testing my N70b1 interior temp sensor actually, so might as well install on my HDMI recorder a good mic and get high fidelity audio while at it.
For road joints the Bilstein B6 at the rear is mild harsh, no choice.
The tires are Michelin Pilot Sport 4, which is not the quietest UHP tires.
The first time I brake hard ( cleaning my rotor disc ) at 1:31 video time, that was 100 miles per hour and usually road noise is much louder at this speed. The dashcam GPS is slow for its update.
Before I did the trunk spare tire noise sealing , discussed here : https://mbworld.org/forums/e-class-w...uch-thing.html
and all the noise reduction effort on this post, and this MLV. sheet.... road noise was higher.
The MLV weight is pressing down on the "noise-maker" trunk floor, as explained below ( post #14 ) : and MLV noise block quality seems working.
The total unsupported width of the floor no 1 is approx 90cm and that is very wide. So on bad roads, this floor no 1 jumps a tiny bit and made noise, very little.
The noise comes from the red zone I marked below :
Okey, cut to fit for the MLV.
The rear portion on-purpose I keep the MLV a bit longer. That zone is the widest noise passage from under the floor board.
10-05-2022, 01:22 PM
when re-open the trunk after 5 minutes....holly cow, what an irritating smell.
