I was annoyed by the level of road noise and required higher stereo volumes at highway speeds as I spend about 10 hours each week in my car. I was also somewhat concerned about the long-term effects on my hearing. I had an SPL meter used to calibrate my home theater and thought I could do a before and after measurement to see what real gains B-Quiet might make.

I drive a 2005 5AT sedan with the basic OEM non-Bose stereo. I purchased a 50 sq. foot roll of Ultimate B-Quiet that came with a small roller. The entire roll weighed about 25 pounds. I removed the rear seat and all trunk area parts and spare tire. I placed double thickness peices over the entire trunk floor and about 80% double and 20% single thickness over the trunk-side wheel wells as I was running out of material. I placed double thickness over most of the areas under the rear seats except for the 2 round 6-inch diameter areas that may be for gas tank access. The install took about 2 hours and was not too difficult. The included free roller was too flimsy to be of much use so I mostly used hand pressure to get it firmly in place. The sticky side of the B-Quiet looks as if it is made from tar, but has no smell. It did stick to my hands, but was easily removed with a little gasoline.

Prior to install, the interior sound levels measured at 92- 94 dB while driving 75 mph on asphalt interstates with the stereo a level 10 and at 90 dB with the stereo off. Driving 60 mph on concrete streets, levels were 90 dB with the stereo at level 7 and 88 with the stereo off.

After install, sound levels were all measured at 4 dB less across all above listed situations. These were made with a RadioShack SPL meter meter set at C-weighting which measures levels between 32-10,000 Hz. You can also use A-weighting to measure leveles between 500-10,000 Hz which is the range of greatest sensetivity for our ears ( I don't know which is used by car reviewers). So what do the numbers mean?

A normal conversation inside a quiet building is about 65 dB. Most sources report 90 dB as the beginning of unsafe levels if exposure lasts for more than 6 hours. It now sounds like the floor of my car is covered with a thick bed comforter. Since hearing loss is a gradual, cumulative and irreversable process, the cost and effort were definately worth it and will likely pay off the longer I own the car. Next up will be the door panels if I can figure out how to remove them without doing any damage.

 

Thanks for the review. I've always wondered about the alternatives of dynamat.

 

I remember reading a DIY thread a long while back. Apparently, on the coupe, the most significant place to reduce road noise / tire howl is a cavity that acts as a resonance chamber for the tire noise. It's the inner-fender area located behind the front wheels. The rear of the plastic fender liner (wheel-well liner) needs to be romoved to access the area. The poster used normal home insulation and wrapped it in plastic, I believe, to fill the majority of that space. His review was that it greatly decreased the road noise and was the most significant area he did. He also removed most of the interior (at least the rear) and did nearly 100% coverage, so I take his review and suggestion very seriously.

This is on my to-do list but it's still just a matter of time.

 

GT-Ron,
Thanks for the info. I could not find the thread you saw. Do you remember what type of insulation he used?

 

It was the garden-variety home insulation from Home Depot or the like. I believe he said he had some on hand so he used it. I do recall him being pretty adamant about that space needing to be filled as opposed to just lining the panels with Dynamat. He wrapped it in plastic to keep it from soaking in and retaining moisture.

 

I tried the above mentioned home insulation project last weekend to see if it made much more difference in road noise levels. It was not too hard and could be done in about an hour if you do not make the mistakes I did. I thought I'd post to save any other who are interested the time I wasted by not being prepared. You will need a good light source, car's jack, Phillip's and flathead screwdrivers, waterproof tape, scissors, waterproof plastic to wrap insulation in, and a regular roll of $10 insualtion from Lowe's.
1. Jack up car per manual instructions.
2. Remove two of the plastic rivets,a bolt underneath and 3 screws holding the plastic peice. You do not need to remove all hardware as the whole plastic does not need to come completely off. Removing the entire wheel is also optional.

3. Cut a peice of insulation in the shape and size of the space and remove about 1/4 to 1/3 of the thick layering of the insulation to allow it to fit in the space.
4. Cover the insulation with the pastic and tape edges together with the waterproof tape making what looks like a little pillow.
5. Cram it into the space and replace the car's plastic peice and any scews, rivets, and bolts you removed in step 2.
6. Lower car and repeat on other side.

 

^review???

 

Indeed! I'd love to hear another review from a second person who's done this. It might be enough to encourage me to do the same.

It looks like you took a slightly different approach by blanketing the back of that piece. From what I recall, the first guy that did this ended up packing that cavity with the wrapped insulation.

I'd definately like to read your review.

 

yeah, howmuch quieter did it get?

 

darnelled

how did you insulate the back though?

 

Anyone bother to hit the underside of the car, the whole trans tunnel and trunk area seemd totally devoid of any kind of deadener when i was under doing my exhaust?

 

Sorry to leave out the review- I was at work and posting this in free time.

The pieces I made were packed into the cavity in the wheelwell space behind the plastic piece I had to remove. I had also previously placed B-Quiet in the trunk and under the rear seat ( as described in the initial thread review).
I did not get to take any sound measurements that would reliably compare before/ after as the next day I got new rims/ tires put on and 350z springs with sport suspension pkg. to lower the sedan. I went from stock with 215-55-17's to 245-45-18's plus lowering which added some road noise before I was able to take SPL measurements.
In city driving, it had about the same effect in the front as the B-Quiet had on the road noise level in the rear. It is noticeable, but not real dramatic.
It allowed me to hear the same radio loudness at 1-2 levels lower than before this project. I will be on the 65-75 mph roads later this week and will try to take measurements. Again, since the mods made to wheels/ suspension it will not really be a true before and after comparison.


Driguez- I looked at doing the rear, but it did not appear possible. There is no removeable plastic piece that creates the pocket of space used to hold the pillow as in the front. There may be some sort of sound-deadening spray available to adhere to the rear's wheelwell area. Let me know if you find any.

 

My main concern is the space behind the front wheels, as road noise at highway speeds is such a roar that it makes conversations difficult, especially from front to rear. This is with the OEM 19's, which seem to be notoriously loud at highway speeds.