Sound deadening layers ...how much is too much??

OP...put this in the FWIW file.

Sound deadening is an art. In this art there is a fine line between enough material and too much. When you get enough to deaden the sound, any additional material will result in diminishing gains.

In truth, you only need about a 50% area coverage with CLD product, then follow with a 100% area coverage of an MLV product. After that......sure you will reduce sound more, but the gains will be small in comparison to the cost.

Reality, the truck cab has multiple sources for noise. Vents, doors, windows, holes for wires and such, firewall, vibrating dash components...... In addition there is the sound from the engine, exhaust, tires, transmission, driveline, wind..........

No matter how thick you add, you will not make the cab an anechoic chamber.

Good Luck.

 

I sprayed the bottom area of the door with fluid film after I did sound deadening.

 

On line there is an old guide showing a sound control "how to" for light aircraft. Makes some sensible suggestions for the deadening process. Basically it says the greatest gains occur when you work on the part of the panel that deflects the most. It shows the dense deadening material concentrated at the center of a panel - smaller double and triple layers built up to change the natural frequency the most.

One of the techniques that worked best on my old bird - layered strips of the butyl material in an "X" across the panel - making a thicker center at the crossing point. Worked just as well as covering the whole area - used a lot less material.

 

In a couple of weeks I will have the entire truck treated with Corrosion Free, an anti-rust oil-based film developed for the Canadian military that was tested against the other widely known treatments and found to be 90% effective rating for inhibiting rust. It's slowly being introduced to the general public, but currently, there are only a handful of U.S. franchises. (My 'closest' shop is 2.5 hrs away.) It's similar to Krown, but has rated higher overall in a bunch of tests and it doesn't drip and ruin stuff under the vehicle after treatment (floor, grass, etc.). After initial treatment, they recommend re-application every 18months - 2yrs. You can also buy cans and jugs of the stuff for DIY application.

I don't now if it's good, but after a lot of online research it looks like the best alternative for me. According to them, any kind of sound insulation won't affect their treatment, but they strongly advise doing any sound deadening work prior to application of their rust inhibiting treatment or else the adhesive for the sound mats will NOT stick ... it's an oil-based formula.

As for other rust-inhibiting treatments? Everybody would need to find out for themselves, as each brand/type may or may not have properties that would affect proper install of acoustic matting. My guess would be to put matting in first, and be CERTAIN that whatever you put in will hold up to whatever treatment you choose for your rig. The matting I chose says it's water & oil proof. I don't know, but I am trusting that it is. Yeah, it will suck if the two won't work, but I don't have a choice. Living in the rust belt dictates that I do something proactive ...or else watch my truck slowly disintegrate around me in very short order. I intend that this is my LAST vehicle, so I have to do whatever I can to protect it and keep it as close to new as possible for as long as possible.

 

Quick question:

Do these black bolted-on extension plates in the back of my access cab perform any important function? I have deleted the back juumpseats, so I have my doubts. I'd just as soon yank them out while the cab is all gutted.

Please advise!
TIY

 

Yeah. I'm trying to be money conscious, but I also don't want to fart around with tearing things back apart to add later on, so I am doing everything I can know, while the truck is all apart. I did make a choice to uyse a less expensive product. Will turn around and bite me in the ass later? Dunno. only time will tell. I can only hope that the results will make all this work worth the effort. I come from an '85 Jeep CJ-7, then an '84 F-250 HD diesel, and most recently, a 2000 Cherokee. I am used to shouting while driving at highway speeds and would very much like to NOT have to do that anymore, so I am doing what I can while I can to eliminate that BS. Every little bit helps.

BTW... just LOVE your sig pic! Long live the transverse twin Honda CX! I owned a 650 SilverWing and a couple of the awesome 500 Turbos. ))))

 

Thanks.

Its an '81 CX500C. Purchased in 2011 as a wrecked non-runner. I did the repairs and restored to OEM condition. Road to handlebar, tire to tire. Even did the paint. There are 5 top colors with clear. It was a daily rider down to 19*F. But....unfortunately....it is sleeping in storage. It went to bed when I took a job in China in 1/2014. Came back 12/2019. Financially, it needs to sleep a bit longer. Maybe Summer of 2022 it could be on the road again. I really miss riding.

 

Did you do MLV in the doors ? I'm trying to figure out how much room there is between the inner door and the plastic door panel.

MLV is 1/8 thick, then a layer of ccf on at least one side, maybe both (between the metal door and mlv, and the mlv to the door panel) so its up to 3/8 of an inch. Some of it squishes down from the ccf, but that still seems really thick.

Hate to waste money on stuff I have to rip out.

 

Not yet, but it's in the pipeline. Currently finishing up butyl in front driver's floorboard. Then MLV the ceiling and reinstall headliner. Then 157mil foam layer (ran out last night. More due in tomorrow; enough to finish the cab floor and back wall). Then MLV on both, then reassemble everything and button the truck back up.

 

When I pulled off the C pillar covers in back on the driver's side I found this exposed female plug just hanging there behind it. I am guessing it goes to some feature that my trim level did not have ( or the PO did not opt for) and is not a concern ??

 

im thinking about doing lizard skin instead of mats.

 

Dont do it. I did it and its a mess, doesnt deaden as well as the stick on stuff, and it gets everywhere.

https://imgur.com/a/nLddWk3

https://imgur.com/a/mA0K6wo

 

Got everything buttoned up but the damn passenger airbag light popped on after reconnecting the battery. I unhooked the seat wires after disconnecting the battery. How the hell did the computer "know" if the battery was already unhooked?? More importantly, how can I reset it without dealer ($$$$) intervention? Can I just unhook BOTH battery terminals and pull the ECU fuses for an hour or so, then hook everything back up in reverse order? Going on trip in 10 days. Must have passenger airbag working for wife.

 

When you can do this...

 

For the record... yanking both battery cables and the abs & EDC fuses and letting it sit for a couple of hours and then re-installing does NOT clear/reset a passenger airbag light fault. At least it didn't for my rig...

So now I must head to the dealer, bend over and take one in the keister @ $140/hr to have the damn thing re-set.

 

I did every single area in my classic car. Covered it all with dynamat then the ceiling got dynamat plus some other liner and the floor got the dynamat, some other heavy stuff they make and then the carpet. Its still loud and I can only imagine how loud it would be without it

 

The airbag module has a backup battery. FSM says to wait at least 90 seconds after disconnecting the battery terminal before disconnecting SRS connectors. It's possible a connector is loose or you need to do a zero point calibration on the passenger detection system (requires Techstream). The FSM says a zero point may be needed if the seat is removed. Clearing codes requires techstream (a nicer scan tool may also be able to do it).

Before you take it in, the FSM has loosening and retorquing the 4 seat mounting bolts (27 ftlb) as a troubleshooting step (there are load sensors on each corner of the seat rails.) If the seat is reclined all the way back that can also trigger the light.

 

What kind of car?

 

The answer is none. Just turn up the radio. This also cures any other noises you may hear...

 

How many layers are you planning on doing?
I'd just go by what the manufactures recommends.
I think most companies will say the butyl stuff only needs to cover up to 50% and then the foam is what stops the sound. I did a 50% coverage on my back wall but 100% coverage of foam. For the floor I did 100% coverage of both to kill the road noise from my tires. It made a world of difference! I used RAAMmat but I believe they are out of business.