Sound Deadening the 80 (5 Viewers)

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Joined
Nov 3, 2023
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28
Location
Bend, OR
Day 1: Prepping for Sound Deadening the 80

If you’re planning to fully sound deaden your rig, just know—it’s not a quick weekend project. This takes time and patience if you want to do it right. And once the material is installed, it’s not coming off without a BIG MESSY fight so do your homework before buying anything. I chose to go with premium sound deadening because I only want to do this once. I plan to keep this rig for life and eventually pass it down to my godson, so spending more up front made sense for me.

A couple months ago, I stripped the interior when I had the exterior painted. That alone was a solid 6–8 hour job by myself, and it set the stage for what I started today.

To kick off the prep, I used a leaf blower and air compressor to clear out all the dust and debris (which there was a lot from MOAB and our dusty trails in Oregon). While I was in there, I pulled the dash gauges and tachometer to replace the dash bulbs—figured I’d knock it out while everything was accessible, and sprayed out those areas as well. Then I went through with a metal scrub brush to remove any lingering fuzz or loose grime.

After that, I deep-cleaned the entire interior with Harbor Freight’s Grant’s steam cleaner and microfiber towels. Once it dried, I wiped everything down with 90% isopropyl alcohol to remove any remaining residue and ensure the surface was prepped properly for adhesion.

Since the interior was already out, I took the opportunity to apply POR-15 to any low points and metal seams where water might collect or where existing rust might have already formed—just a little insurance against future rust. I also sealed the edges of the factory sound deadening to help prevent moisture from creeping underneath it down the line.

If the POR-15 cures by tomorrow, I’ll begin laying down the first layer of Resonix Mega CLD Squares, aiming for roughly 90% coverage across the floor. I’ve invested about $2,000 into materials for this project, with the goal of reducing road noise, improving sound clarity, and enhancing thermal insulation. I’ve got a quality audio system going in, so I’m treating the foundation with the same level of attention.

I didn’t do a decibel reading before the teardown, but I’ve got plenty of local 80s to compare against later. Honestly, I’m confident it’ll be a big improvement either way as I've done this on previous vehicles.

I’ll continue to post updates as I make progress. If you’ve got any questions, drop them below.


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Day 2: Got 40 sheets (12”x12”) installed today—and I’m already out. Still haven’t finished the floor, doors, or parts of the quarter panels. Definitely underestimated how much material I’d need. Unfortunately, it’ll be a couple weeks before I can pick this back up.l as the materials are on back order.

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The stick on butyl only stops ringing in the panels. Whack them before and after. You need mass loaded vinyl or foam of some kind (weight) to absorb the lower frequencies and sound in general
 
Does your sunroof rattle? Since you have the headliner out, you should have access to more of the sunroof mech including the rollers that get flat spots.

The sunroof on mine def' rattles and I want to address it but its not worth pulling the headliner to get to it.
 
The stick on butyl only stops ringing in the panels. Whack them before and after. You need mass loaded vinyl or foam of some kind (weight) to absorb the lower frequencies and sound in general
That may be a thing on something with thin sheet metal, but an 80 is fairly robust. I can't see much ringing happening once all the seats are bolted up. I plan on removing that stuff I installed next time i have the interior apart. Maybe someone has some sound measurements though to say otherwise.
 


This guy covers all of the bases. Mass above all else is whats required once you stop the ringing of panels at various frequencies
 
I used that foil sound stuff. Didn't notice any difference. I believe most the noise from an 80 is lower bass type noise, which requires different materials.
It really comes down to the quality of the product you choose. This stuff is top of the line—extra-thick butyl and heavy-duty foil. To really notice a difference, though, you’ll usually want to add a layer of closed-cell foam or fiber mat on top (which is what I’m doing).
 
Does your sunroof rattle? Since you have the headliner out, you should have access to more of the sunroof mech including the rollers that get flat spots.

The sunroof on mine def' rattles and I want to address it but its not worth pulling the headliner to get to it.
Never noticed a rattle to be honest, but if I find any loose rattling objects, that will be deadened. Thanks for your input.
 
The stick on butyl only stops ringing in the panels. Whack them before and after. You need mass loaded vinyl or foam of some kind (weight) to absorb the lower frequencies and sound in general
That's in the works as well. Need to finish the CLD first, then that stuff goes on next.
 
Impressive undertaking. How much weight do you figure this has added? Keep it up,
 
Daaaaang. I did similar on my Rx7, but only about 35lbs - much smaller interior - and a lot easier to remove everything to get to what you need. I wore heavy leather gloves and used a roller (*Dynamat) but still ended up with a few cuts. I considered them blood sacrifices,
 
I finally got mine on the road after doing the dynamat, Noico Foam, Jute, and new mass backed carpet. I ordered, but did not use, mass loaded rubber sheets. I would not do the mass backed carpet, the odor is horrible and I will be replacing it. I will say it is far quieter than what it was.
 
I used noico strategically and it really helped with the doors and rear quarters. Changed resonance and lost that tinny sound in those spots. Now a much more manly thud.
 
Did this task about three years ago. I would do a few things different. I used Second Skin products. Painted a coating of Firewall ceramic coating (not impressed), followed by Damplifier Pro then Dynamat. It's made the Cruiser much more quiet.
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I noticed a big heat soak difference under the passenger seat and into the second row. Especially during long trips the floor doesn't get super hot anymore.
 
Fwiw, 100% coverage for vibe/resonance damping is definitely unnecessary and just wastes material/money.
That being said, I installed ~70lbs of Amazon Basics in my 80 and the difference was impressive.
 

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