Bed vs Bedliner and soundproofing - need advice

I have been wrestling with soundproofing my 2020 TRD Sport for months and have read much, posted a little. I have addressed the doors and floor in the truck. Long story short- I have a 6 ft bed and have isolated the road noise which is driving me nuts to the bed and the oem tonneau cover. Inspecting my bed, what I thought was a bedliner seems to be the composite bed. Is there any way to put sound isolation material between the metal outside bed wall and the inner composite ? It seems they are molded together but there is a 3-4 inch gap between which allows sound to resonate .
If not I plan on either trying the BedRUG Product vs putting mlv and deadener on the composite, or both.
Finally has anyone else noticed more noise w the trifold oem cover down than up? Thinking of going back to a revx
Thanks in advance

 

The gap between the composite bed and the outer fender is open to the pavement, and water and road debris gets in. If you put sound insulation in there, it will get wet and then you will have a mold problem.

 

Not sure I quite understand. Sound comes in from the bed?

 

Using closed cell foam egg crate you can spray glue them to the insides of the bed panels and it will absorb the sound.

Just remove the wheel liners and you can get access to the area. Spraying bedliner will still allow the sound to reverberate inside the quarter panels.

 

Is the noise you hear coming from the cab air vents in the back of the truck?

 

My thoughts too. It'll be solving a symptom, but not a problem.

 

Not to mention rust if touching the fender

 

Do the back wall of the cab. That made a huge difference for me. And I just used some noico no real sound deadening.

 

Thank you for all replies. I have a road hum which comes from the bed through the closed window. I am not crazy - I have measured it w a sound meter. It is better w the tonneau open or off, so I think there is a harmonic created between the sound in the bed and the closed cover. All I want to do is put some dynamat or other on the inside of the metal, and some mlv. I was looking again tonight- I don’t see a way to separate the composite inner wall and the metal. I will try applying to the composite itself.

 

Thanks but no- I have addressed the back wall and vents already. Definitely from the bed- can localize by opening the rear window.

 

Good news. As you get older you become increasingly deaf. Eventually you don’t care as much. In the mean time I have used the same trick since the 80s. Crank Thunderstruck..no more road noise.

 

The heavy OEM bed mat should deaden some sound.

 

It's a fairly inexpensive and cheaply built mass produced truck and it sounds like it.

 

Ive been chasing the same thing down.

Sounds like a hum / light whine, that is not RPM or speed dependant. Just makes the same noise at 30+ or so.

It's much louder with the rear window open .

It almost sounds the same as a cheap fuel pump, for context.

 

Someone can validate my experience! I don’t know igniting unique to certain trucks or not, but waaaay louder than my past Chevy truck. I find it only on certain interstates, but I mostly drive interstates. Still searching for a fix

 

I also have a 6ft bed, but mines an access cab.

I ALSO have removed the rear seat panel, applied sound deadening, and used foam over the air vent to mitigate the sound.

Didn't really help at all.

It wasnt till I drove the other day with the back window down, and could hear how much louder the whine was, that I knew it was coming from back there somewhere.

I'll probably find a safe road, have my SO drive, and stick my head out the back and see if I can localize it.

It might just be a plug or something that whistles when hit by wind. That or I'll bust out the tape and start covering things till it's gone.

Idk but it's driving me crazy. Doesn't help that I'm OCD with this stuff lol.

 

If you put a protective bed mat, available anywhere, plus a tonneau cover on it, you will likely get rid of most of the sound. I am still trying to figure out the sound issue, as I get none, but my premium interior probably has more sound deadening in it.

 

Do the besides on the 3rd gen not unbolt from the composite bed just like on the second gen?

 

I think they do. That is the final solution. I’m going to try soundproofing the inner composite wall which is easy access and then reevaluate. Like other people have posted the sound is coming through the rear glass not the rear seat soAny more insulation in the cab is not
Likely to help.

 

turn the stereo up...thats what an old mechanic told me years ago..