Smart ForTwo 453 Cabin Noise!! Is it legal??

[mrmcrae]

So I have picked up a new ForTwo Sport Prime Premium Plus 0.9 Turbo and I can't believe how loud it is inside when driving. It is so loud I am worried about my hearing and starting to resort to wearing hearing protection whilst driving it!!

My daily commute consists of 22miles mainly on A roads and the cabin noise reaches an average of 92-95dB using Decibel X App which compares this against a food blender and a motorcycle?! I have seen it spike to subway noise levels!! I believe safe exposure levels are below 85dB. For what I can remember even when idling the cabin noise is still above it!

If I new it was this loud I may of considered something else. Now I am considering sound proofing the thing! In fact I have already used some Dynamat on the engine cover and that has had no noticable effect. I am looking at different tyres now to hopefully reduce it further but I'm not sure how much that will take it down. So I think I will have to start taking out carpets and fitting more sound proofing! This is getting expensive...

Anyone else have this issue and have you done anything about it? Such a shame as its a fun little car to drive.

[Thrumbleux]

Are you sure there isn't something wrong with it? Eg, some mechanical component making direct contact with the chassis where it should be rubber insulated (engine mount, suspension bush, etc...)
The dB levels you quote sound to be far too loud,

[mrmcrae]

I don't believe there is something wrong with the car, just bad sound proofing and standard tyres fitted from what I have manage to find out so far. I will have a look around the engine bay, not sure how easy it will be to see anything obvious. The bulk of the noise seems to come from the right hand side rear wheel and door. It is a new car that had 10 miles on the clock and still less that 500 and been like that from the beginning, so hopefully that's not the case.

[BBE]

I have a Brabus and I fully agree with you regarding cabin noise. I remember my reaction to this on my first drive home from the dealer.
I have never done any measures, but 95 db seems like a bit steep; are uou sure your measurement is ok ?
Anyway, I can tell you that most of the noise comes from the rear wheels. When I first changed to winter tyres (as everybody in Norway does before the winter),
there was a significant reduction in the noice. I use the nordic (Wiking) version of the Continentals which has a softer version of compound.
I once removed the rear wheels and the inner fender to see if I could find the reason for the high noice.
What I found is that on the back of the inner fender smart has added a diaper looking pad in the middle of the fender which I doubt has much effect.
Also, above the inner fender there is no covering at all, just open space all the way up. I am pretty sure this is where the problem is.
I have not done anything to this so far, so if you do, then I will be most interested in hearing your experience.
Bjorn

[mrmcrae]

BBE I am waiting for some continental WinterContact TS860 tyres to come so I'm interested in how that works out, good to know that you have noticed a significant reduction! so that's promising. The tyre has come top a few years in a row and best for reducing cabin noise (even though the rolling noise is reported slightly higher than the ContiEcoContact 5 by 1dB which I have on at the moment). I have learnt that cabin noise and rolling noise are different things, so I'm trusting the reviews and not the tyres stats on this one.

Like you mentioned, I think I might look at removing the inner fenders and sticking some dynomat onto those areas and see if it helps... Was it straight forward to remove and reattach?

[mrmcrae]

fullsizeoutput_550.jpeg
Just back from a test run to update my readings which were slightly incorrect however still a concern.

Idling - 61.3dB
60mph - 88-91dB
70mph - 89-95dB

I have attached a 3min recording, even though it was a longer drive it would only let me export that length of time for free.

I might contact smart and see what they say about these noise levels, it can't be right.

[mrmcrae]

I have just tested with a different app called dB Meter Pro for comparison and there is a big difference in measurements (about 10dB) so I would say that my posted results are inconclusive. None the less its still loud enough for me to be concerned about.

[Chopper]

Did you not notice this when you feet drove the model prior to purchase? If not, then it could be something wrong with your particular car.

What are the tyre pressures set to? Last time I looked at a car for this the boots had been pumped up to over 40psi by a Muppet tyre fitter. Resetting them to the correct levels cured it.

[mrmcrae]

Sort of noticed during a test drive, but didn’t think it would affect me as much as it has been. I’ll check my tyre pressures tomorrow, didnt think of that.. kind of assume all should be correct from a new car, but good shout!

[tolsen]

Lucky I am blessed with a whisper quiet 450 diesel. A needle dropping on the rubber floor mat can be heard in mine. No road noise and hardly any sound from engine.

[mrmcrae]

Swapped over to the winter tyres now. First impressions, I think it has reduced the cabin noise around the 60-70mph mark but not much. I would say it was more noticeable around the 30-40 mph mark. I think I’ll have a go at sound proofing the drivers side rear wheel arch

[mrmcrae]

Anyone have any pictures on what it looks like when the wheel and trim is removed? Not sure how much room is available f or sound deadening/proofing, so can't order any just yet. Was looking at getting it done next weekend. Anyone recommend what you would use in the area. Was thinking more dynamat but I think that stuff needs to stay inside the car... so maybe some of the 4mm waterproof sound proofing type stuff by Noico might do the job, I would imagine the thicker the better but how much space can I play with is the question...

[mrmcrae]

Purchased some more sound deadening and sound Isolator sheets from SilentCoat. Fitted 1 sheet of sound deadening behind the drivers seat, wanted to add more but meant taking a bit more carpet up which I couldn't be bothered to as it was getting dark. Then I though sod it, I will try adding a length of sound isolator foam in the wheel arch (temp) to see what it would do. Went for a test drive and again not much of a difference, I think it may of helped as I don't think the noise is coming directly coming from behind my right ear. So now I am suspecting its the drivers door. Anyone taken the door trim off before?

[mrmcrae]

Not sure if anyone is reading these messages anymore... but just in case some is looking for more info I'll keep adding.

So the other day I took it out for a 2.5hr drive mostly on motorways and noticed the droning noise I experience wasn't that bad at 70mph. A quick check on the meter and it was hovering between 74-76dB at 70mph. What was strange is that the droning noise started coming back 60mph and below. If I have time at the weekend I may add some more soundproofing where I can. I still feel that there is a lot of noise getting in through the door, so I will look at taking that appart....

[ColSmart]

Have never driven a 453 Fortwo, but those noise levels seem very excessive, have you went back to another dealer for a test drive of another 453 with same engine for comparison? Take it on motorway at 70 MPH. Then if your car is noisier then take it back to your dealer for sorting.

I have a 451 Cdi and as it is a bit noisier than a petrol car at idle, but quietenough on the move, so I sound insulated with car underfelt over the boot but under the carpet, using 2 rolls to put two layers down in boot, and cost was around £30 with post and packaging, it made a difference. note I also insulated down the short bulkhead behind the seats, but avoided rear of the handbrake mechanism..... .

[2fortwofamily]

With the sometimes (ok, often) leaky nature of Smarts i'm loathe to put anything other than bitumen mats down for sound deadening, the engine cover & beyond being a quick job in the 450 on a nice day, got to do the rear arches on one this spring as the love of discounted goods code meant a bigger pack for less.

I'm also dubious as to the excessively high db reported, you need to validate those numbers, however NOISE like musical preferences is down to the ear & mind of the person hearing it.

Is the engine cover loose? (that pin is about a fiver to replace if so, ditto the seal it may / may not sit against).

Yup, I realise this is an old thread.