[Aces_High]

Given how fucked up the conditions of the surface streets and freeways are in Los Angeles, I find that perhaps BMW insulates and sound deadens the cars they manufacture to a level appropriate for European roads, and that that level of sound deadening is inadequate for the subpar Metropolitan roads in America. I dunno how to quite explain it but I'll give an example:

Often times while driving certain stretches of freeways, for example certain stretches of the 5 freeway south of the 110, it sometimes feels my BMW isn't a BMW. Feels and more importantly sounds like a piece of junk. I know this gross interior noise intrusion is primarily caused by the poor quality of the road surface. I know when I drive on new or newer asphalt the ride and QUIETNESS is just absolute bliss.

Hope thats understandable. Now my question part:

Is there any affordable/practical/DIY way of reducing the amount of road noise that enter the cabin?

I've recently done a lot of close examination into things, and a bunch of research . I'm concerned with addressing the amount of noise that makes its way into the cabin from the floor/wheel well/ trunk/firewall areas. I feel the car is awesomely aerodynamic. Wind noise is quiet enough that when I'm on a clean new/er highway @ 80mph, its so beautifully quiet inside, with that faint hint of the inline 6 , revving away merrily @ 2600rpm.

I've recently done some looking into sound insulation/deadening products for automobiles. I've come across dynamat, fatmat, etc. All see to say they more or less do the same thing. Does anyone have any experience with these products on Bimmers? Also is there anything lightweight like a thick neoprene (that soft material for laptop sleeves) pad?

Weight is important as I dont want to add a 100lbs onto the car.

Another question, does anyone know where most of the noise intrusion takes place?? is it near the wheel wells? transmission shaft? or the bottom of the car(since it rides closest to the ground)? ??

I'm real serious about doing this, for two reasons:

1. 90% of the time I ride in the car in absolute silence (ya cell off, radio/ipod off). I have a 10K sound system @ home, I bought this thing to enjoy driving the hell out of it. hehehe dont hate me I know I'm wierd.

2. I want my Bimmer to sound like a Bimmer irregardless of what road surface I'm navigating her through. I know that shitty roads will translate to shitty rough ride. I Agree! .......but it can have that quiet isolated feel that it always has.


Plz rain in some comments/critics/suggestions/ideas

[arabbmw]

i think getting a softer suspension might help. it will absorb more shock so other things in the car wont shake.

[Aces_High]

ya thought about that a lot. but I dont want to change the feel of the car, as i find it awesome, and at the same time I dont think the softer suspension will have any bearing on the amount of noise.

[jasonn]

Alot of reputable audio shop can help you with dynamat and what not. They make a huge difference and I have sat in cars with and without it.

[JO3]

The easiest and cheapest way of doing what you want is to get more luxury oriented tires. Kill the noise at the source.

IMO, the sound will travel through the physical connection between the tires, suspension and chassis, so you won't be able to get rid of it completely with dynamat or similar solutions.

[ronn16E90]

it is the RF tires that are making those "like plane noise" i read some forums about changing tires with just normal ones. because RF has something in it that makes the suspension hard.

[StarrDlux]

nah its tire brand in general. you buy a noisy tire its going to be noisey there are plenty of non RFT tires that have alot of road noise.

i think the bmw is quite sedate honestly.

[Aces_High]

has anyone swapped tires and noticed an reduction of cabin noise? i searched and found quite a few threads on tire swaps but they were more perf orientated. so anyone done it for noise reduction??

also if swapping will produce the desired results, shall i pick up better RFTs or regulars? I've got that tire/wheel protection shit so I don't mind having them replace 20 RFTs per year =)

[urbanite]

I installed Michelins this winter (X-Ice I think, I'm embarrassed to admit that I can't remember!) and then Kumho Ecsta ASX for this summer. Get rid of the run flats! Both the Michelins and Kumhos are far quieter. I found it amazing when I replaced the run flats with the Michelin winter tires in the fall, and the new tires handled better and were less noisy! And the Kumhos are great too.

[continentalg5]

As it was said before, Dynamat will probably help out a considerable amount.

[JackMac]

The tires are the primary source of noise/rumble in any vehicle.

I briefly had 19" non-RFT tires and it was much improved. Going to the extreme, 17" non-RFT all-season will be very quiet. But you will give up some of the BMW handling crispness.

[tintivilus]

From the OP's comments about the poor quality of roads in US metro areas, I'm thinking he's talking about impact (crack/seam/joint) noise rather than flat-pavement tire noise. Wouldn't this be primarily transmitted through the suspension?

Softer tires (think "Grand Touring", not sport) would help, as would taller sidewalls.

If you're concerned about weight I don't think you'll get far with Dynamat. Isn't the whole theory of operation there to add mass to reduce resonance?

[ibimmer954]

Roads are constructed differently in California compared to the midwest. That much I know for sure. A lot of the highways have these "grooves" in them that they don't use in Illinois or they use different materials without the grooves. I think you get more road noise in CA than I remember growing up in the Chicago area.

[atom]

Originally Posted by Aces_High

has anyone swapped tires and noticed an reduction of cabin noise? i searched and found quite a few threads on tire swaps but they were more perf orientated. so anyone done it for noise reduction??

also if swapping will produce the desired results, shall i pick up better RFTs or regulars? I've got that tire/wheel protection shit so I don't mind having them replace 20 RFTs per year =)

I know that in my GTI, tires make a HUGE difference in road noise.

I've driven on the stock 17" goodyears, 17" Potenzas RE960's, and on 15" Dunlop wintersport M3's. The bigger sidewalls on the snows makes them the quietest of the 3. The Bridgestones are TONS quieter than the stock tires.

I would assume that since the runflats are stiffer, they'd be louder. I'd swap for regular performance tires and see how that helps before I added the weight of dynamat.

[stressdoc]

Tires and dynamat.

Trade-offs between quiet and performance (although high quality non-rfts are a win-win), sound insulation = weight. Get a tune, dynamat, expensive non-rfts. Maybe consider suspension mods like Koni fsd.

[purplewidow]

your rft's..it's pretty simple get new tires with thicker side walls..that will make it more quiet..i have to say i am extremely pleased with the sound deadening..but i think it deadens it too much..if you add dynamat your gonna be adding weight and changing the weight distribution depending on how much you use..going between rft's and non rft's will make the difference..when i put non rft blizzaks on my car became much much much quieter.i really think you should change your tires first then change other items.

funniest thing is your in SoCal..i mean those roads are like heaven compared to us that just went through one of the worst winters in history..i mean we had so much ice it was unreal and the snow slows dig up the road..what does socal have to worry about..to much sun? i mean i have been to La recently and i didn't think the roads were that bad..i think you need new tires and that's it..the sound level of road harshness went from a 7 to a 4.5 when i switched and that was going from summer rfts to winters..i think i might get a lil more noise when i put the Ps2's on b/c they are a harder tire..you really need to look at tires with a larger sidewall..if your old car was on 15 or 16 inch rims with old fatty tires that is where you might be hearing a large diff..i drove my 540 yesterday and though i haqave the dinan suspension on her she is soo quiet in side all i hear is my engine and exhasut roar and my fat tire michelins do a great job of creating virtually no noise..low profile tires with rfts creat the harsh noise you are talking about..and if you still want it to be more quiet switch to a different suspension setup.. but that will make the car handel like ass..shit the more and more i write i think you want a buick not a bmw

[BK]

Originally Posted by stressdoc

Trade-offs between quiet and performance (although high quality non-rfts are a win-win), sound insulation = weight. Get a tune, dynamat, expensive non-rfts. Maybe consider suspension mods like Koni fsd.

+1 Dynamat probably is the surest way to deaden the sound in your cabin, but it is notoriously heavy.

[Pike]

Keep in mind that noise insulation/reduction and sports-car handling are in opposition. Wider, lower-profile tires (especially RFTs) will generate more noise in all kinds of conditions. Anti-roll bars will also transmit more noise to the chassis. And so forth. If you could float the car like a boat on very soft tires and suspension, it would be quieter, but it wouldn't drive like a BMW.

For my part, I think the E9x is way too quiet, but I'm coming from an E30 and an E46 M3. To each his own.

Frankly, you probably wouldn't notice an extra 100lbs of dynamat or equivalent sound insulation material, in most everyday driving. As others have said, some well-placed insulation might help. But I wonder if you'll be bumping up against the law of diminishing returns here. The last time I stripped out the interior of an E30 I was shocked at how much insulation ships from the factory. I imagine an E9x must have *much* more.

[lauer87]

Like others have said, get non-RFTs and your problems will most likely disapear.

[jetblk328i]

Ok if you have the turanza tires, you can get them swapped for free!!! thats right! i went to my dealer and told them that the road noise was unacceptable and i got a free set of contis... better but not great(i have a lexus lol) but give it a try!!!

[Storto]

I used to work at a car stereo shop for about five years. I have used all different types of sound detoning materials. Here's how they work; The basic principal of sound detoning products, dynamat etc., is pretty simple. If you increase the mass of an area, it will take more energy to make that area vibrate, less vibrations = less noise. That's all that these products do is increase mass/weight.
If your going to do it, I recommend buying the spray. You can get aerosol cans of it or, if you have an old paint gun and an air compressor, you can buy it by the gallon.
I think that spraying the undercarriage would probably give you the best results. Just make sure you tape off any thing that you don't want coated.
If your worried about weight, you can decide how many pounds you want to add prior to starting. Then weight the can/container. It's difficult, but lightly and evenly cover the undercarriage while periodically reweighing the can/container until you have used the amount you wanted.
Some of the sprays are different colors, make sure you get black if you do your undercarriage.
I hope this gives you so insight, or maybe some ideas.

[-=Hot|Ice=-]

I blame RFTs.