Author Topic: Semi-truck soundproofing  (Read 12423 times)

Peter

  • Guest
Semi-truck soundproofing
« on: January 28, 2001, 05:11:25 PM »
BJ:
I have a 99 Freightliner semi that I have been trying to soundproof since it was new. I have installed an automotive carpet pad (about 1/2"), removed panels from the walls and bunk area and installed (this should make you laugh) spray expanding foam in an unsuccessful attempt to reduce road/engine noise. It is now very well INSULATED and comfy in bare feet but virtually no reduction in noise or vibration. My floor area is approximately 6'x5'. The walls and bunk area total about 15'x8' but I only have access to about 10'x5' due to cabinets, bunk structures, etc.  The bunk area gets a lot of rear drive tire noise since it is literally 2 feet from the drivetrain and exhaust noise as the stacks run right under the bunk to the back of the cab. Additionally, Freightliner has repeatedly attempted to replace the hood insulation (foam w/ foil backing) by regluing with some type of fiberglass glue.  The glue gets brittle and after opening and closing the hood multiple times, it simply falls off leaving a very rough glue mess behind.  I have no access to the door panels as the mechanic labor guide calls for about 2 HOURS to remove. (You have to remove mirrors, outside sheet metal etc.) so I think I need to focus on the floor and bunk walls.
Overall, the interior sound level is so high that you cannot hear someone talking in the bunk if you are in the drivers seat 4 feet away. My wife and I wear earplugs (from the pistol range) when sleeping. I flew with a pilot friend in a Beechcraft King Air that was quieter than this stupid truck. My wife and I drive as a team so the truck runs close to 24 hours a day. What do you think?
Thanks
Peter

bjnash

  • Guest
Re: Semi-truck soundproofing
« Reply #1 on: February 05, 2001, 02:42:47 AM »
: BJ:
: I have a 99 Freightliner semi that I have been trying to soundproof since it was new. I have installed an automotive carpet pad (about 1/2"), removed panels from the walls and bunk area and installed (this should make you laugh) spray expanding foam in an unsuccessful attempt to reduce road/engine noise. It is now very well INSULATED and comfy in bare feet but virtually no reduction in noise or vibration. My floor area is approximately 6'x5'. The walls and bunk area total about 15'x8' but I only have access to about 10'x5' due to cabinets, bunk structures, etc.  The bunk area gets a lot of rear drive tire noise since it is literally 2 feet from the drivetrain and exhaust noise as the stacks run right under the bunk to the back of the cab. Additionally, Freightliner has repeatedly attempted to replace the hood insulation (foam w/ foil backing) by regluing with some type of fiberglass glue.  The glue gets brittle and after opening and closing the hood multiple times, it simply falls off leaving a very rough glue mess behind.  I have no access to the door panels as the mechanic labor guide calls for about 2 HOURS to remove. (You have to remove mirrors, outside sheet metal etc.) so I think I need to focus on the floor and bunk walls.
: Overall, the interior sound level is so high that you cannot hear someone talking in the bunk if you are in the drivers seat 4 feet away. My wife and I wear earplugs (from the pistol range) when sleeping. I flew with a pilot friend in a Beechcraft King Air that was quieter than this stupid truck. My wife and I drive as a team so the truck runs close to 24 hours a day. What do you think?
: Thanks
: Peter
A: As you found out, carpet padding, carpet, liquid foam, fiberglass, etc are all pretty much useless for noise, but make good thermal insukation.  It was probably our soundproofing in your friends plane!  You need our Aircraft soundproofing booklet, download it or read it at the link shown or we can mail you a copy.
I can't tell you what to do, but I'll tell you what I'd do: If I was serious, I'd start from scratch and tear it all out, cabinets and all.  Remove the panels and remove all that stuff that don't work.  
I would inspect the inside very carefully for gaps and crevices that could admit air and caulk them up. I would the apply our foam soundproofing mat to the inside of the walls and bunk area. If the inside wall had a 2" air space between the outer wall and the inner panel, I'd install  1/2" soundproofing mat on both, creating a 1" airspace. If it was 3", it would be 1" mat amking a 1" airsapce.  I would use the same mat under the hood, but 2" thick, applying it (after cleaning all the old stuff out) with contact cement and some machanical fasteners too.
I would cover the whole floor with 2 or more layers of the SSP "Floormat" we sell. (1 layer of "floormat" and one layer of "flooring").  Windows? If plexigalss, replace then with glass ot 3/8" thick plexiglass.  
Doors? Pull the panels from the inside and cover them with as thick as SSP mat as will fit and replace the panels.  You may be able to reach inside then and glue matting to the inside metal of the outer door panels.  Check doors for proper sealing, too.
This type of soundproofing WILL work.  You will amaze your friends and confound your enemys!  Better, you will be able to talk and sleep.
BJ

 

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