Cab Insulation - TOO LOUD!

[claybodie]

Hi all,
I am wondering if any of you have experience with cab insulation, either with some of the sound dampener products out there (ie Dynamax, LizardSkin, etc), ashphalt sprays, home insulation, whatever.

The cab of my truck is so loud on the freeway that even with earplugs and ear muffs (a 30-45 dB reduction!) my ears ring after an hour or so! There are some holes in the door that I am taking care of, but it's going to need more than that.

There is a great tutorial/research website, http://www.sounddeadenershowdown.com that gives a lot of good background on this topic.

It may seem like a waste of money to some, but my ears are worth some $$ and I am going to use this truck until its last day, so I will be going overboard on sound deadening.

Any input would be appreciated.

[redmondjp]

Your truck has cab insulation?????

Mine doesn't, and it has the rubber floormat which doesn't work as well as the carpet does. I picked up a heavy cut pile carpet with a 1/8" thick heavy barrier layer underneath, and 1" of carpet mat inbetween, out of an '86 or '87 Nissan out at Pull-a-Part (think it was $6 or something like that). It's pretty dirty--I've cleaned part of it so far, but haven't finished it yet. I expect this to really help bring the noise level down. Adding that adhesive mat material to the bare cab floor and walls behind the seat, and to the firewall as much as possible I'm sure will drastically reduce the noise level. Inside door panels too. Just haven't found the free time yet . . .

On my maiden voyage in my pickup, bringing it back from eastern WA where I purchased it, I had to stop after an hour and stuff tissue paper in my ears the noise bothered me so bad (I had a headache from the get-go, which made me extra sensitive to noise anyways). These trucks weren't designed for low interior noise, that's for sure! Around town it doesn't bother me. I use ear plugs on the highway as well . . .

One other thing to check for is wind noise at your side window and door seals. Brand-new door weatherstripping is still available at discount places on the internet, for $50-60 a pair which is a pretty good deal. Also, the glass channel seal on the earlier trucks was in multiple pieces, with the short vertical piece right at the front of the door glass usually slipping down into the door. The later (85?-86) cabs had a one-piece channel which won't do this--I've liberated a few of these out at P-A-P as well, and you can easily install it just by rolling down the window, pull old channel seal out, install newer one (first clean it with a toothbrush, blow off with compr. air if you have it, and spray on a silicone or graphite-based dry lubricant and you'll be set).

IMO adding sound insulation to one of these is a worthy investment if you spend a fair portion of your driving time above 30-40 mph.

[asavage]

Funny, my '82 KC diesel didn't seem noisy at all. My Rabbit diesels were torture to drive, I'd have a headache after driving from Portland<->Seattle.

[philip]

SNIP-
The cab of my truck is so loud on the freeway that even with earplugs and ear muffs (a 30-45 dB reduction!) my ears ring after an hour or so! There are some holes in the door that I am taking care of, but it's going to need more than that. SNIP

Find an '84 or later 720 4x4 (esp an ST) and peel back the carpet. You'll see a layer of sound deadening material bonded to the floor board. Then there is a layer of rubberized material, fiber matting, and finally the carpet. In the cheap models (like my '82 SD), there is the rubber mat and thin sheet of rubberish material. That's it.

If you have work hardened engine mounts, this will contribute to noise resonance.

Periphery weather stripping on the doors is another check point.

Lugging the engine will generate a pounding drumming.

My truck has NO sound deadening between the roof and the headliner. This makes the entire roof reverberate at times. If I yell, I can make the roof ring!! That's scary, idden it!

[philip]

SNIP- The cab of my truck is so loud on the freeway that even with earplugs and ear muffs (a 30-45 dB reduction!) my ears ring after an hour or so! -SNIP.

Back in May of '82, "Car and Driver" said the diesel truck was like riding inside a 50 gallon drum during a hail storm! Of course C&D said a few other things in the article that aren't true.

[ffdjm]

I glued backpackers sleep on foam, the 3/8" thick stuff with contact cement, more for warmth than sound reduction. On the top and back of the cab. I had to remove the floor insulation to fix rust. Water enters around the wheel wells. I use carpet scraps from the local dumpster to cover the floor and do not fasten them down.

I drive with ear plugs all the time. After 25 years I am used to it.
I will stay used to it until the automotive industry starts making 35 mpg pickups again.

Douglas