Time To Refine

[seduced]

So I just used Dynamat Xtreme in the boot and the rear parcel shelf.

Now just to clarify - Dynamat is NOT a sound barrier/absorber!!! It merely takes the vibration out of panels to improve the decay on frequencys running through said panel. Basically it stops vibration, therefore reducing vibration-sourced noise.

To reduce road noise and tyre roar, a sound absorber or barrier is required. This is why its seriously overkill if you dynmat every square inch of panel inside your car.

The required amount is 25% coverage to deaden a panel. I went about 50% coverage in the boot area and under the parcel shelf. I dont believe adding more and more dynamat would improve it further. You only want enough until the panel ceases to vibrate. To absorb some road noise, I chose a heavy blanket I had laying around and placed it under the boot carpet. The combination of vibration deadening and sound absorbing material is astonishing!!! The amount of diff virbation I used to hear is significantly lower, the road noise is dramatically reduced from the rear. I havn't purchased another dB meter to check what difference, the one I've got is giving false readings..(98db at 80km/h apparently!) One thing I have noticed - the road noise used to be louder from the rear, it is now much much quieter than the front. I can really hear the front tyres now... annoyingly. that's for another day...

Also, the factory sub has suddenly come alive! I deadened the rear parcel shelf fairly heavily around the sub, just enough til the vibrations ceased. For the first time, the factory sound system actually sounds good, great bass response that now happily vibrates the rear-view mirror like crazy! Everyone who has premuim sound should deaden their parcel shelf as a minimum. The results are fantastic! My mate asked if I installed a sub... he didnt even know there was a factory one, you could never hear it properly...

This is only stage one. I am sourcing some better sound absorbing material and I plan to completely line the boot well, rear quarters, under the rear seat and more under the parcel shelf. Also, the reaminder of the dynamat will line about 50% coverage inside each door and along the driveline tunnel. The sound absorbing material will also be placed as a barrier inside the each door and possibly under the entire carpet. Although the factory carpet is very thick as it is... I will also fill the ABC pillars with sikaflex 227, especially around the base.

Under the car, I will fill that chassis cross member with more sikaflex 227, and make a rubber bush between the diff cradle and the chassis mount. My car did have the Ming Sound deadener sprayed everywhere when it was purchased, so I wont need to apply anymore. I will however apply heaps around the front and rear wheel well covers.

Lastly - I noticed my std diff bush has 4 hollowed sections (bf mkII, different bush to previous models) but the design is bad. I managed to video the bush under load. The bush streches to the point that the diff bolt actually sits on the diff cradle because of these hollowed sections. Which is why I get some much vibration under full throttle. I am going to fill the sections with sikflex 227 to prvide extra strength and cushioning when under load.

A full write up and pics will be produced when I'm done.

[seduced]

Ok, after much searching I have found the best stuff to use for sound absorbtion and a barrier.

What you'll want to achieve is to reduce the amount of low to mid frequencies you can hear from the tyres, engine, exhaust, driveline. A simple roll of jute or foam will not achieve this. Neither will layers and layers of dynamat. As mentioned above, dynamat and other variations only reduce panel vibration, they are not effective sounds barriers or absorbers. In saying this, they are still very much needed for a good overall result.

The product is called SoundMat from and Aussie company SoundControl. Soundmat is a heavy (8kg/m2) sound absorber and barrier and super-effective at reducing road noise etc. Its a mass loaded vinyl and only a few mm thick. Its also flexible and easily cut with a stanley knife. It comes in a 1350mm x 5m roll (Enough to do 2 - 3 cars) and costs $510 for the roll. Expensive, but it is the best. Also means I dont have to line the wheel wells or any other underbody parts.

So I will buy this product in a few weeks and install by chrissy. The results will be fantastic - as they say... it will be Lexus Quiet... nothing wrong with power and luxury! Whats annopying is that Ford wouldnt install this at factory... it would cost $500 per car, and boost the quality of the ride enormously. I'm sure we'd happily pay an extra $500 for a luxury quiet ride...

[Daniel]

I would confirm adding mass to the parcel shelf increased the performance of the factory sub, significantly.

It wasn't even something I was thinking about or expecting... I was driving around in my car with the stereo off to gauge the difference in road noise after putting a few different materials on the surface of my boot and after having a listen I put my stereo back on and wow, it was like a 'what the heck, why is there so much bass/lower mids all of a sudden?'

In my boot I had the same Dynamat liner you have used, with an adhesive foam covering and then a THICK dynapad to top it off!

I too notice only sound from the front now...

Cant wait to see how you go with this new material.

[Guest Al@n]

As a new anally retentive member, this attention to vehicle refinement is absolutely incredible. There are obviously people out there that are taking DIY refinement to the next level. To those that are willing and able, well done. Thinking laterally is something that we all struggle with at times. Concratulations for your innovation andscreativity, it is tremendous, and allows us all to understand the benefits of thinking outside the square, Cheers

[wiresquire]

Hey guys

Much respect for your attention to detail.

I'm interested in the premium bass getting a little boost. But as a newbie on the sound side, I have a few questions.

OK, time to begin stupid questions:

- Would just doing the rear shelf with Dynamat be worthwhile?

- From what I see above, the parcel shelf needs, say, 50% coverage. And most of that's around the sub. Does the dynamat go under the sub as well or just around it? Where do you actually 'attach' the dynamat. Pics would be awesome :D

- How much (square metres or whatever) Dynamat would be required to just do the parcel shelf?

- What's a rough cost to cover the above so I know I'm not getting ripped off?

- Where can I buy this stuff?

Thanks for help in advance

ws

[seduced]

Dynamtting the rear shelf is very much worth doing. Its like a light switch on your sub, doesn't sound too bad for a factory unit.

All you would really need is a dynamat xtrme door kit or two to get the coverage you need for just the shelf. I only put patches of dynamat on the underside around the sub and wherever there was a flat space. There are alot of holes and bumps on the shelf, so just work around them. Have a look under there, you will see where you can put dynamat and where you cant. Once you have about 50% coverage on the underside, you will find its probably enough. Remember, you only want to stop the shelf from vibrating. You are not sealing anything or reducing road noise etc.

You could get away with it for less than $50. Im not sure how much the door kits retail for, as I purchased the bulk pack to do the whole car. I ordered mine from Ryda.com.au, they were the cheapest.

As for an update for this thread, I have scored a ChassisEAR diagnostic set-up which will pin point noisy parts of my chassis and boot area, I'll then be looking at improving those points. I am yet to purchase the sound barrier gear from SoundControl as christmas has killed my financial plans once again....

[wiresquire]

Thanks very much for the info.

Much appreciated!

ws