Riding in my Landie means I don't have to hold a Conversation

[Santana]

I recently put a radio in the old Landie with the knowledge that I really wouldn't be using it while on the road. More for the picnic area you see. But it got me thinking about sound levels in the vehicle and what was "acceptable". Dare I think that I might be able to lower the Decibel level?

After thinking on it I started to daydream my wife and I getting ready for a Sunday drive and her saying, "Let's go in the Land Rover." Instead of her saying, "It's so loud I can't relax."

With all this rolling around the brain I think that I will see if I can start a sound proofing project. Maybe a little Dynamat here and there to see if the noise levels change or money is just going to get thrown down another hole.

Starting a project like this means that I needed a way to measure success or failure. Being a big fan of my iPhone I took a look on the appStore and found one called PocketRTA. An application used by sound people for checking their sound stuff, blah blah blah. I measured the sound levels in my truck while at idle, high rev and off. I quickly found out that finding a quiet environment for tests was going to be very hard. Since I live in the city traffic noise from the street was throwing all my measurements off. The quietest place I could find was an enclosed compound. I had my unit set to a base of 0 decibles and took a reading. The reading came out to roughly 30 decibles with the car not running. With this I think it would be safe to subtract 30 decibles from any noise readings I take in the car as a sort of zeroize. Below is a reading from revving the engine. So if I subtract my base reading i.e. quite environment that gives a reading of 35.7 decibels with engine revved up to oil pressure at 60 psi.

In the coming days I'm going to make some more measurements on the road and will post them here. I put some Dynamat for the hood and doors on order and expect them in about 2 weeks. If it works out that I get at least 5 to 7 dB lower readings then I'll investigate other measures that can be taken.

[jrd51ox]

Use eBay for the Dynamat, it's half the price.

I did the doors, hood, inside the seat box, under the floor panels and the piece that goes over the stickshift.....it resulted in major heat & noise reduction.

Good Luck.

[leafsprung]

With this I think it would be safe to subtract 30 decibles from any noise readings I take in the car as a sort of zeroize.

Im no sound guy but I dont think that is a correct assumption.

[amcordo]

Im no sound guy but I dont think that is a correct assumption.

Ditto. Sound doesn't work like that, and decibles are exponential so a reduction of 30 db is pretty large. Vernacular aside, reducing the sound pressure in your LR is going to be difficult. The PO of my "jeep" (I stopped correcting everyone because it was getting tedious) tried to reduce sound throughout the vehicle by placing dynamat, dupont insulation, foam insulation, and carpet in every void throughout the vehicle. While that helped a bit, the BIGGEST gain in noise reduction he created was by sealing the vehicle.

Keep in mind that a air-filled void can work just as well as dynamat in reducing sound so long as it is well-sealed in. This is why real, purpose built recording studios are built off the ground of the structure they're in and have false walls around them.

If this is really bothering you go around your vehicle and caulk (or something similar) all of the gaps between floorboards, bulkhead, etc. with the goal of having no places air could get into or out of your vehicle - ESPECIALLY on the bottom. Also add the wiper strips to your sliding windows. This will have teh double benefit of keeping snow and rain from blowing backwards into your truck when passing in a larger vehicles slipstream.

You'll notice a significant drop in noise from doing this.

Finally, adding a surface absorber for noise in your car like carpet will help to reduce the pebbles in a pop can syndrom our vehicles suffer from. When noise DOES slip into the car dynamat or other insulation hidden under surfaces wont stop it from bouncing around inside the car, and all of the metal surfaces just echo like mad. Carpet or a sound insulation foam (looks wierd in anything but a church or a recording studio, but...) will help.

[LR Max]

Do it. That is one modification I'm interested in doing soon. That and an insulated headliner. In the hard tops, the sound just resonates.

I was looking at sound proofing my Subaru STi (sold it before dumping money into it ) and I found this website:

http://www.raamaudio.com/

This guy seems to sell good stuff, cheaper than dynamat. Will probably order like, 3 rolls from him when I get ready to do my 109. He also has some spray stuff. It would be cool to do the reverse side of the panels with that stuff. Would probably help and you'd only use like, 5 cans or so.

[JackIIA]

Do it. That is one modification I'm interested in doing soon. That and an insulated headliner. In the hard tops, the sound just resonates.

I was looking at sound proofing my Subaru STi (sold it before dumping money into it ) and I found this website:

http://www.raamaudio.com/

This guy seems to sell good stuff, cheaper than dynamat. Will probably order like, 3 rolls from him when I get ready to do my 109. He also has some spray stuff. It would be cool to do the reverse side of the panels with that stuff. Would probably help and you'd only use like, 5 cans or so.

Have you checked out Eastwood? They also have a competitor to Dynamat that is cheaper. Don't know if it's better than this guy's. Just another data point.

[Winooski]

Having tried to solve the rattle and vibration issues in my truck, I bought a small sheet of Sorbothane, cut it into (2) 6" x 12" pieces and glued it to the bulkhead behind the seats. For only $20, it reduced a significant amount of the noise from the truck's natural motion. Driving noise and sealing air issues aside, this may help someone looking for vibration/noise reduction. Not as universally applicable to all aspects of the truck as Dynamat, but still not bad.

[Tim Smith]

I ended up redoing my headliner with closed cell foam and covered that with fabric. It was great for sound and heat but clearly the rest of the interior would benefit from a similar treatment.

I believe the flat surfaces are the biggest issue to resolve if you want to reduce sound levels.

[redmondrover]

sound

As part of swapping the chassis on our 109, I took on the task of minimizing noise. I went to www.hamiltonjet.com. They sell a product called Dexdamp that is essentially the same as dynamat--$5 per two square foot peice--as well as a matting that is a combination of limp mass vinyl and closed cell foam. The dexdamp will go on our newly galvanized bulkhead. I have installed the matting on the seatbox and will also line the footwells and middle row seating area with it. In addition, I have made a real mess under the seatbox and in the fenders with a flame retardant expanding foam. FInally, I am installing 1/4 inch closed cell foam and a fuzzy hull liner as the headliner. Hopefully, all of this will make a difference....

[Tim Smith]

Here is my mini walk through of doing a headliner with closed cell foam and fabric. Not much but maybe it will give you some ideas.

http://picasaweb.google.com/smithco1/BumbasHeadliner?authkey=Gv1sRgCJzMg46bneCP5gE&feat=directlink

[redmondrover]

Headliner

Thanks for the pictures and info Tim. That is very helpful.

One thing I learned from the place I bought the foam and hull liner (www.perfectfit.com) is that the 3M spray adhesive is the same as the adhesive used to install laminate countertops and that you can buy a gallon of it for just a little more than the cost of one can of the spray. Since I was also recovering the lower dash and gluing down the limp mass vinyl/foam on the seat box, I went bought a gallon at Home Depot. I just brush it on and, so far, it works great. Although it does not give you much of a chance to reposition so it is best to go a two or three inch strip at a time.