Under cab insulation

Plumb Bob

Member
I added a piece of this SuperWool Plus product on the bare metal cab floor above the radiator and fan. I'm chasing the fan noise mostly, I suspect it will help with heat also.

It did make a noticeable difference in the sound reduction from the fan on my trial run. Lynn Manufacturing is the supplier, they may sell small sizes at their site, or buy rolls on Amazon.
 

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pugslyyy

Expedition Vehicle Engineer Guy
Looking good! I've found that a butyl sound deadener (dynamat, etc) can help a great deal as well.
 

Plumb Bob

Member
yep, I use the sound deadening inside, doors, roof, under floor mats, up under the dash, everywhere I could reach. It seems to my ear, this engine compartment component made the biggest improvement. No hard data to back that up, just a mechanical troubleshooters sensitive ear.
 

Jesse42

Member
Looks great! Can you share some more info about how you attached it? It looks like you did not follow the curve of the cab metal and instead left some distance. Am I reading the after photo correctly? Also, did you use the 24”x1/2” roll of Superwool Plus?

Thanks!
 

Plumb Bob

Member
I used 1/2" long Zip, aka duct screws with a 1" diameter fender washer. With the sound deadening, factory pad and floor covering above, the points of the screws do not protrude enough to cause a problem.

The black insulation seen in the pic is factory installed. It is held in place with plastic push pins, which do stick thru the floor also, about a 1/4" hole is needed for those attachment.

Correct that it does not fit the contour exactly and the 24" wide pieced do lap a bit. I used just enough screws to keep it in place.

These were sample pieces that the company sent me to try after I described the application, 2 pieces about 60" long, 24" wide. I think the aluminum coating makes it easier for the fasteners to hold. There are other high temperature products available without the aluminum jacket.

Amazon has 25' rolls, probably enough to do the entire underside of the cab.
 

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javajoe79

Fabricator
I have my cab mostly stripped out except the dash frame and wiring. I’m going to completely strip it soon and spray it all with homemade lizard skin. Actual lizard skin works wonders so I’m hoping it will go well. I might spray the underside too.
 

skippythedog

Observer
Hmmmmm....one of the basic tenets of sound deadening is to have a break between metal parts from exterior to interior (thermal and sound)......Those screws transmit sound and maybe some heat.... Gotta be a better way...Perhaps nylon rivets or even shaping lengths of semi rigid metal strap around the perimeter to minimize screws....I'm no expert but this is what the local car stereo guys tell me.
 

javajoe79

Fabricator
Self tapping screws are banned from use on vehicles in my shop. I hate them. If they're sticking out under the cab, it's inevitable that someone will rip themselves open on one. I'd replace them with rivets or just glue the mats down.
 

Plumb Bob

Member
Plenty of bolts thru the cab on these trucks, it would be tough to isolate all them, I'm not concerned about a dozen #6 screws transmitting sound. Anything over the bare sheetmetal cab helps a lot. Depends on how far you want to chase sound deadening.

I agree on screw points and I dull them with a die grinder. In this case the screws are from the bottom up and the points are only exposed if all the cab insulation and floor mats are removed. i doubt the points extend thru the sound matings glued down inside the cab.

Good tip to watch for needle sharp self tap screw points.
 

Spanna 53

Member
Doing the freeway trip back from Queensland to Vic and at 95 to 100kph the wind noise is still a problem the engine fan can still be heard but Dynamat made a big difference even had no music on at one stage and could hear the boss
 

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