S212 interior road noise

[phobos]

Right, Saturday! Measurement day.

Got a SPL meter from Amazon and a massive 13 tog duvet...

At both 50 and 70 mph I got with SPL meter around 75-77 dB.
With the duvet where the spare tyre is located, i got 72-75, so between 2-3 dB of gain which is pretty good!

Also done an interesting test with a A4 piece of paper.
Put the piece of A4 paper between the door seals, close the door and ty to pull the paper.
Driver and passenger rear door - need to do quite a lot of strength to get the paper out
Driver and passenger front door - easier than rear doors, but still some strength required.
Tailgate - super easy to pull out the paper ( there is only 1 rubber seal as all the other doors have opposite rubber seals )

I would expect that the tailgate seal should seal better, but having said that, I hear road noise, not necessary wind howling noise..

Has anyone replaced door seals and saw a reduction in road noise ? Or should I consider better soundproffing?

Many thanks

 

[190]

I have an Excel file of dB measurements at idle and various speeds. It covers over 1500 cars but I can't post it as it's not a permitted file type. Here's a couple of screen shots of some Mercedes models. It's a few years old so doesn't cover the latest models.

Diesels are obviously noisier than petrol and an interesting observation is that newer versions of the same petrol models are not necessarily quieter which I believe is due to the adoption of direct injection engines which are inherently nosier than port injection.

 

[phobos]

I have an Excel file of dB measurements at idle and various speeds. It covers over 1500 cars but I can't post it as it's not a permitted file type. Here's a couple of screen shots of some Mercedes models. It's a few years old so doesn't cover the latest models.

Diesels are obviously noisier than petrol and an interesting observation is that newer versions of the same petrol models are not necessarily quieter which I believe is due to the adoption of direct injection engines which are inherently nosier than port injection.

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Hi 190,

Thanks for the information, very informative.
Do you know where the measurements took place, UK or Europe as the tarmac might have played its part.

 

[190]

I couldn't remember where it came from as I've had the data for a few years, so I was surprised how easy it was to find the the source simply by doing a web search for "dB at idle"


It looks to be German

desktop

 

[phobos]

Thanks, looks like the tarmac played a big role.
Did some more experiments today and tried 4 different types of road and you can definitely hear the different between different tarmac takes some of them being much noisier than others...

Oh well, I will try to should deaden the wheel arches and properly sound proof the spare wheel well and see what results I get!

 

[ChrisHGTV]

Thanks, looks like the tarmac played a big role.
Did some more experiments today and tried 4 different types of road and you can definitely hear the different between different tarmac takes some of them being much noisier than others...

Oh well, I will try to should deaden the wheel arches and properly sound proof the spare wheel well and see what results I get!

Hi Phobos - did you try using some sound deadening? I think more out of interest than anything i bought some Silent Coat deadening to try on my S212. I don't find it loud tbh but i was curious to see if i could make it any quieter - it does seem to be noisier from the rear. I was going to try adding some to the spare wheel well and the rear wheel arches but not sure how easy they are to get to, i've not really looked yet. From what i understand it's not necessary to cover the whole area in the deadening mat but just enough to stop any resonance?

 

[esscee]

Have you tried placing the duvet just on the floor of the rear compartment? Reason for suggestion is that I used duvet to protect an item I was carefully transporting in the back to another location. Then on the return journey without the item, I noticed how much quieter (less road noise) the car seemed especially being able to drive at "normal" motorway speed.

 

[Gazwould]

Hi Phobos - did you try using some sound deadening? I think more out of interest than anything i bought some Silent Coat deadening to try on my S212. I don't find it loud tbh but i was curious to see if i could make it any quieter - it does seem to be noisier from the rear. I was going to try adding some to the spare wheel well and the rear wheel arches but not sure how easy they are to get to, i've not really looked yet. From what i understand it's not necessary to cover the whole area in the deadening mat but just enough to stop any resonance?

Yes .

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Tap out with a knuckle the most resonating parts and apply .

 

[phobos]

Hi Phobos - did you try using some sound deadening? I think more out of interest than anything i bought some Silent Coat deadening to try on my S212. I don't find it loud tbh but i was curious to see if i could make it any quieter - it does seem to be noisier from the rear. I was going to try adding some to the spare wheel well and the rear wheel arches but not sure how easy they are to get to, i've not really looked yet. From what i understand it's not necessary to cover the whole area in the deadening mat but just enough to stop any resonance?

Hi Chris, I have only put a massive old duvet where the spare tyre goes and it has quieten down a bit. Having using sound deadening ( on the boot of my old S211 I think you will need a combination of both - sound deadening and a sound absorber to obtain a half decent result.

Also what tyres do you use?

 

[ChrisHGTV]

Hi Chris, I have only put a massive old duvet where the spare tyre goes and it has quieten down a bit. Having using sound deadening ( on the boot of my old S211 I think you will need a combination of both - sound deadening and a sound absorber to obtain a half decent result.

Also what tyres do you use?

Thanks, I’ll give the deadening a go then can add some absorber or a duvet if I feel it needs more!. I’m using Goodyear Eagle F1 assymetric 3 on the rear and Dunlop SportMaxx RT 2 on the front. I normally use Eagles but the Eagle 5 seemed quite a bit noisier (71db) than the older 3 (69db) so went for the Dunlops Which are actually 68db

 

[190]

If you have a removeable access plate for the parking brake adjuster under the rear seat, check that it is correctly sealed. I made a noticeable reduction in road noise by removing the plate and re-sealing it properly.