Noise Reduction 101
This project was started after I changed out the exhaust in favor of a better breathing system. After installing the exhaust my wife gave me one of the looks on our maiden voyage with the trailer in tow. The drone was really hard on the ears between 1500 and 1700 RPMs, and while pulling grades.
My first attempt was to use some under coating under the truck. While it helped a little it was not going to be the answer. I purchased a 12 Sq Ft piece of Dynamat Xtreme and did the back wall of the cab. It helped more, but now I had exhaust noise in stereo coming up both rear pillars as well as a drone from the floor of the cab. So I then went searching the internet for additional products that were not as costly as Dynamat. I found B-Quiet in Canada, they sell a product similar to the Dynamat product but for a lot less money, I also found Cascade Audio Engineering (CAE) in Oregon.
Like everything else with these trucks, everyone you talk with has a different answer how to go about reducing the noise level in side of your vehicle. The one thing most did seem to agree upon was that multiple layers were the way to go. Some recommended layers of different materials while others recommended different products in different places.
What I feel is one of the major areas/causes.
The way the cab is designed, the pillars and the door threshold areas extend below the floor of the cab. That creates an area that is hollow and exposed from the under side to all the noises that happen under the truck. This noise spreads up the pillars, across the floor and greatly effects the noise level inside of the cab.
What I Ordered.
A 100 Sq Ft roll of B-quiet Extreme and 2 Cans of Spray on sound barrier VB1 from CAE. Additionally I went to a local auto paint supply store and bought a can of semi rigid foam spray in.
Of the products I purchased I have 9 Sq Ft of B-quiet Extreme remaining, this is only because I forgot to install the second layer in the rear foot area.
Preparation.
I gave myself one weekend to do the work. I began removing the interior on Thursday, starting with the back of the cab. As I removed items, I placed them in the garage in a position that represented where they belonged relative to each other.
I had to keep the truck drivable thru Saturday so I could drive it to work, this slowed things down a bit.
Everything was reinstalled by the following Monday.
Installation.
Installation went fairly well once I figured out how big a piece I could handle (about 2 Sq Ft). The firewall area was a real pain just because you have no room to work. I installed a minimum of 3 layers of B-quiet Extreme to the tunnel and 2 layers to all floor pan areas except the rear foot area. I used a wall paper seam roller (since my fingers weren't doing the job) to ensure that the product was well adhered. I sprayed the CAE Sound barrier on the side and rear pillars as well on the door thresholds. I split the can of semi rigid foam between the two rear pillars filling them up to just below the seat belt attachment points.
Places you need to watch.
The tunnel area where the center console mounts (if you have bucket seats). To many layers on the sides will make for a tight fit when remounting the center console.
The plastic trim pieces. (Pillars, front kick panels and door threshold plates) Since the carpet is under these, to many layers in these areas will make it hard to reassemble, and possibly cause the door kick plates to pop loose.
The front seat belt carpet anchor point. I currently have nylon collars installed. This allows for the attachment to pivot as designed.
Results.
The project made a major difference in the interior noise level. The exhaust drone and road noise levels were reduced as well as the wind noise in the rear pillars. I no longer get those looks from my wife.
What I Would do Different next time.
Buy more of the B-Quiet sound deadening material. I measured the cab and calculated that I would need about 75 Sq Ft of product to do two layers on the floor (P.S. this is a crew cab). The back wall of the cab takes another 12 Sq Ft. So a 100 Sq Ft roll would have probably worked had I been very precise when cutting the material. The problem with that is there was no way to cut it that precisely.
Apply a layer of the B-Quiet product to the pillars instead of spraying them. That will take another 12 Sq Ft or so.
Get a second can of the expandable foam and use it to fill the rear pillars a little higher as well as putting some in the center pillars. (Ford did put some foam into the bottom of the center pillars).
Make sure to
have a minimum of 2 layers on all horizontal surfaces (most companies only recommend
one layer on vertical surfaces).
I choose the B-Quiet Extreme as it looked to be the easiest to work with. After further consideration, the brown bread might have been a better choice for the floor and tunnel areas. The B-Quiet Extreme would still be a good choice for the pillars and back wall of the cab.
Recommendations.
Get at least 150 Sq Ft of product if you plan on layering it.
Put a flex pipe into your exhaust, if you don’t have one already.
Check out Donald Ward's article on Soundproofing. It was recently published in the Winter 2002 edition of the Power Stroke Registry.
1/23/2003
Today I added the under dash sound insulators that Ford is putting in the Excursions.
Part numbers YC3Z-78046A24-AA and YC3Z-78046A25-AA
They consist of molded plastic panels backed by about a 1/2" sound absorbing material. Passenger side went in rather easily. You use one nut that is already on the firewall, drill holes and install 2 screws under the glove compartment. The driver side still needs a little refining, You use one bolt from the accelerator pedal assembly and there are three holes in the front part for screws. The problem is that there is no easy place to attach the panel. Need to check on some fasteners.
From the little I drove it they seem to muffle the engine noises that were coming through the firewall and under the dash.
2/3/2003
I finally decided to go and buy a sound level meter. I purchased a Radio Shack model 33-2050. Indicated accuracy of +/- 2db @114 db. It measures both (A) and (C) weightings. The (A) weighting primarily measures frequencies in the 500-10,000 Hz range, which is the area of greatest sensitivity to the human ear. The (C) weighting measures uniformly over the frequency range from 32-10,000 Hz, giving an indication of the overall sound level.
A dB (A) reading of 45 is an average residence, a 60-65 is talking, and 75 is an average factory. When the dB(A) increases by 10, the subjective loudness of the sound doubles.
The outside truck readings were taken with the sound meter held at the grill just below the Ford badge. The inside readings were taken with the sound meter held on the top of the center console with the microphone even with the front.
My truck is a 99.5 F350 XLT Crew Cab, long wheelbase, auto. The exhaust consists of a 3 1/2" down pipe and 4" the remainder of the system. The tires are 10 ply all terrain at 65 PSI. The sound readings were done on a asphalt surface road.
dB(A) dB(C)
Outside background sound level <55 56
Idle Outside truck 88 91
Inside Truck 56 79
45 mph 2200 rpm (accelerating) 70 85
55 mph 1575 rpm 68 85
56 mph 2200 rpm (overdrive switched off) 70 85
57 mph coasting 66 84
60 mph 1730 rpm 68 85
65 mph 1875 rpm 69.5 86
70 mph 2000 rpm 70 89
75 mph 2130 rpm 71 88
80 mph 2260 rpm 71 88
Comparison Vehicle
Bone stock 99 F250 XLT Crew Cab, short wheelbase, auto, with 8 ply Mud terrain tires at 55 psi.
dB(A) dB(C)
Outside background sound level <55 <55
Idle Outside truck 90 92
Inside Truck 59.5 82
55 mph 1575 rpm 69 89
56 mph 2200 rpm (overdrive switched off) 70 89
57 mph coasting 68 89
60 mph 1730 rpm 71 89
65 mph 1875 rpm 71 91
70 mph 2000 rpm 73 93
75 mph 2130 rpm 73 93
updated 2/11/03