Access Cab noise reduction process

Hello friends,

I decided to so something about the road noise and do a little refurbish on my dog deck. I'll document the process here.

Step 1, gut the rear wall right down. No step by step on this, it was already mostly gutted due to the dog deck:


Notice something missing? It's the cross member that I don't recall ever seeing fully removed in other builds:


Not shown is me leaving the bins out for (temporary) reinstallation - dog deck mkIII will feature hinged trapdoors to access that compartment.

But back to that cross member, why did I pull it out? There are gaping holes in both rear corners of the cab here that are only covered by little plastic plugs:



Clean out the surprising amount of filth down there and degrease everything (EVERYTHING) with denatured alcohol:


Fast forward 3 hours and you've got 75% coverage with Noico 80mil deadener:


And then decide to go ahead and use the rest of the 10sq ft box:



Elapsed time at this point is 4 hours from the start.

Things I learned: 1) You can split the Noico tape lengthwise easily by following the tips of the diamonds on the printed logo. 2) Butyl is real sticky shit if you get it nice and warm. 3) According to everything I've read, this level of coverage is probably past the point of diminishing returns. Whatever.

Those holes in the corners got 2 layers of butyl:


If you do this yourself, here is something to consider:

I personally don't mind removing and re-applying fresh butyl if I ever need to get to those holes, but you should make up your own mind.

At this point the "knock test" sounded great to someone who had never done this before (me), so I moved on to the Noico 150mil closed cell foam:


I got as close to 100% coverage as I could with 18 square feet, including all the way up to the edges behind that remaining factory trim. This meant a lot of patches and seam-covering strips where I didn't get everything perfect edge to edge. Let's just say a lot of learning took place here:



Elapsed time to this point: 7 hours.

Waiting on delivery of MLV, but I wanted to at least get done what I had on hand. I'll update you with MLV installation and the new dog deck as they happen.

Can't wait to hear the next noisiest part of the cab!

 

Looking good. IMO, you should take the side panels off to complete the access part of the cab.

When I bought my AC, I pulled the seats, carpet, removed the door panels and the headliner to put in a two part sound deadening system. Took me a the weekend to do, and so glad I did. Went from a tin can sound to a thud if you tap on the doors or the top of the cab. Only wish I had taken some pictures of the process.

Thanks for the posting about the process. Please keep updating.

 

Those gaping holes are where your cab mounts to the frame - the rear cab mounts. Probably best not to cover and seal those as they may need to be serviced in the future.. just a thought

 

I'll take care of those sections when I do the rear doors, for sure. Even with the rear bulkhead vent un-stuffed (I previously had it baffled) and no MLV yet, the noise reduction especially at highway speeds is great so far. I can hardly wait to do more.

That's good info for sure and something others may want to consider when having a go at this.

If I personally ever need to get to them from above, I don't have a problem scraping and re-applying more butyl - the noise reduction is worth the potential future hassle to me. The "stick your head down there at speed" test indicated that those corners were LARGE contributors, which makes sense - the way they're placed, if you told me they were designed to funnel road noise into the cabin I might believe it.

 

LOOKS GREAT, been on my list to do for years now lol. Does the Noico leave any kind of smell behind?

 

Nope, not even right out of the box.

 

You've persuaded me to tear mine back apart. I've already done the noico base layer, and some other topping foam, but have developed a "hollow" knocking sound I can't seem to locate. Time to fix my halfassery from before and locate my annoying sound once and for all

 

MLV showed up... A 70 lb roll of the stuff, enough to do probably 2 or 3 AC tacos, doors and back wall.

I measured 52.5" off the 48-inch roll, and cut the factory trim to fit the MLV behind it. That black line is one cut, and I realized after taking the pic that I would need to make the same cut on the section below it:


While I was at it I also cut this guy off:


I kept it when initially prototyping the cargo/dog deck in case I found a use for it. Never did. Away it goes and a chunk of foam goes over the hole.

I rassled the MLV edge to edge behind the rear trim:


And cut a "step" profile so it would fit the top contour of the factory trim at the top while going corner to corner behind it:


My rear panel is held in by tabs behind the deck and two factory headrest bolts, and fits exactly between the factory trim:


I marked those bolt holes by smashing the rear panel in place and poking through with a screwdriver, then trimming around with a box knife:



I trimmed the mat in-place with a box knife to fit the contour of the storage cubby, and reinstalled the deck and rear panel (not shown). The way the panel attaches, the MLV is sandwiched tight at the very top of the rear wall where the rear panel meets the cab, and it hangs more or less loose and floppy behind the rear panel.

The noise reduction is incredible, considering what a pop can it it was to begin with. Next up, probably doors.

 

Awesome and you're right about the results. That MLV looks a lot like the second part of two part sound deadening system I used. I ordered my system from;
https://www.b-quiet.com/

 

I'm not familiar with that product. It looks like maybe a combo of the closed cell foam and MLV layers?

 

Yes https://www.b-quiet.com/collections/all-sound-deadening-and-sound-dampening/products/vcomp

 

Hmmmm, interesting. Looks like a labor saver for sure.

 

Well lets just say it was a labor of love and the desire for a quiet ride. As I mentioned (and like your project) mine was a two part system. I first laid down this https://www.b-quiet.com/collections/featured-products/products/b-quiet-ultimate-50-sound-deadener before adding the vcomp on top.
My project took the weekend working about 8 hours each day which included gutting the cab and putting it all back. While I was at it I also added some thermal and acoustic liner to the underside of the hood.

Glad to see your project moving forward.

 

That's a hell of a lot of work and money. I just hope your dog appreciates the effort

 

I did a few panels in the doors and was going to do the roof. Is more sound transmitted through the back wall?

 

The back wall and especially the interior of the rear floor cubby seemed like the noisiest parts to me by far, but then again I ditched the factory interior so long ago that I don't remember if it made that much of a difference.

If he could talk I'm sure he would thank me, it's gotta be a lot nicer to lay down back there now. The $$$ wasn't actually too bad.

 

Hey @deanosaurus, speaking of... how about posting a picture of your pooch?

 

Yeah, he appreciates what you're doing. That's one happy feller!

 

Awesome.

Tell me more about the plastic caps? They're just open to the underside of the truck? Would it be possible to route wiring through there without removing the cross bar?

Do you have any more pics of the area?