Sound Deadening Benefits on the 5th Gen 4Runner – What is sound deadening and why should you do it?
Sound deadening is the process of making your 4Runner’s interior quieter.
It can drastically reduce the sound of common rattle, road noise, roof rack whistle, oversize tire hum, and general vibrations that might be heard or even felt inside the cab. Doing this can also improve the quality of your audio, stock or aftermarket.
There are a couple of reasons why you might want to sound deaden your 4Runner, but mainly its to reduce common road noise and improve audio performance.
#1 – Reduce common road noise
At higher speeds, you tend to hear more noise coming from your 4Runner. Whether that’s from external accessories, factory elements, mother nature, or anything else. Higher speed tends to cause noise. Sound deadening can have a big impact on reducing these commonly heard sounds.
#2 – Improve audio performance
Most factory audio systems are lacking clarity in the highs and mids, along with that profound thump that makes any good system worth a damn. The 4Runner’s factory system is pretty weak so sound deadening is one option to consider if you are looking to improve the quality of your audio. After deadening your doors, floors and rear hatch, you can expect some impressive improvements to the factory system.
What material should you use?
- CLD (Constrained Layer Damper)
- CCF (Closed Cell Foam)
- MLV (Mass loaded vinyl)
When it comes to sound deadening any vehicle, you typically have three layers; CLD, CCF, and MLV. Each of them plays a role in the sound deadening process but they also each come with more weight and added costs.
Total Material needed?
The total square footage of deadening the doors, floors, and the rear hatch is about 110sq ft. Initially, I was thinking it was 150sq ft to be safe but you can pull it off with around 100sq ft or even less if you go light.
I overlapped many pieces so I had complete coverage in many areas, in other words, I layered it on thick!
If you are deadening on a budget, you can likely get away with 75 sq ft. That is if you are smart about where you place each piece.
You don’t need to layer it on as thick as I did. You can be somewhat selective and place CLD in the wide-open clearings on your sheet metal.
CLD (CLD is Constrained Layer Damper)
What to buy?
The silver stuff (commonly known by Dynamat) that you see plastered all over Google images is called CLD (Constrained-Layer Damper). CLD is an anti-vibration material.
This is the main layer that is referred to as “sound deadening” or “vibration-damping/deadening”, it’s a thick tar-like tack-adhesive material with a rigid outer metal layer that can stop or limit sound that resonates through your sheet metal.
The CLD sheet absorbs the energy/vibrations then suppresses the vibration so that the current (sound waves) can’t pass through the sheet metal, thus any noise-creating energy is lost.
It’s not a soundproofed material in itself. However, it will reduce sound because it has mass. Anything with mass is going to reduce sound but the CLD is strictly designed to suppress vibration.
The material is made of a visco-elastic membrane with an adhesive backing. The adhesive is very minimal and forgiving. You can apply, and peel back if you need to but if you do this too many times, you will somewhat degrade your CLD damping sheet which will need to be re-applied.
There are many different brands of CLD out there, Dynamat is just one. In the example today, we are using Mat 66 but Kilmat is another very popular option on Amazon.
CCF (Closed-cell foam)
What to buy?
The second layer is the CCF (Closed-cell foam). The CCF will decouple a sound wave, meaning it breaks up the sound. Closed-cell foam has tightly-woven cells that produce a “closed” effect between two other layers. Closed-cell foam results in a denser material that works better at absorbing low-frequency noise.
Closed-cell foam is basically a gasket between two layers. You can lay this down in between layers in order to prevent contact between CLD and MLV for example. It creates an air gap or spring between the mass loaded vinyl (MLV) barrier.
MLV (Mass loaded vinyl)
What to buy?
The third layer you can add is mass loaded vinyl or MLV. It weighs 1lb per sqft. This is what can really “soundproof” your 4Runner. Because the MLV has so much mass, it really quiets things down.
MLV can get pretty expensive like CLD but from what I have read, it can have an extremely dramatic result on the final product. This is what professionals use when clients are looking for the best possible “sound deadening” solution for their cars, trucks, and SUVs. This is typically found in extreme audio performance upgrades.
CLD (Constrained Layer Damper) Overview & Benefits
For our deadening process on the 4Runner, we are only using CLD.
You have a few options for laying your CLD (Dynamat, Kilmat, Mat 66, Etc.). Buy whichever one suits your budget best. I went with MAT 66 at the time because they had great reviews and the lowest price. I wanted to break this down into four different parts. You have four main areas of sound deadening; the doors, floors, roof, and hatch.
Sound Deadening Areas:
#1 – Sound Deadening Doors
If there is one area that will have the biggest impact on the actual deadening of the sound, it’s doors. Applying CLD to your doors will limit the sound coming from the road, your wheel wells and everything in between. Not only will the sound noise be minimal, but it will also drastically improve your audio performance.
We initially started our entire deadening process because of the TreadWright Guard Dog MT tires. Oversize tires, in general, have a tendency to hum/howl around 30+ MPH, especially mud terrains. If the sound of the tires were a level 10 before deadening, it turned to a level 5 with sound deadening doors.
After testing out the audio, I was blown away. We recently installed the OEM Audio Plus speaker only upgrade and the sound improvement comparison is somewhat comparable. You are not able to go louder with your volume like a speaker upgrade but the bass hits much tighter and the highs are less distorted.
OEM wins in the audio upgrade department, though. If you have endless funds and want minimal work put in, OEM Audio Plus is a great best option. If you want to pull your door panels off and spend an hour per door (at least) installing material, then look at deadening.
If you install an OEM Audio Plus system and sound deaden your doors, watch out because you likely just entered the recording studio.
#2 – Sound Deadening Floors
The floors were next on my list as the main item of concern was the TreadWright MT tire noise. By deadening the floors I was hoping to take the tire noise down even more than a level, and it worked. From level 10, I got the tire noise down to about a 3.
This was a huge accomplishment for me because the MT tire noise was a little out of control. That “level 10” noise I mentioned above was too loud for a daily driver.
The floors also kept the road noise to a minimum as well.
Do you know when you are cruising on the freeway or around town and the road surface type changes? At that moment, you can instantly hear the surface noise either increase or decrease. This typically happens from asphalt to concrete. Concrete tends to have a louder road noise than asphalt.
After spending some time on the freeway and around town, there is a noticeable difference in road noise and especially the surface changes.
Don’t expect the road noise to be eliminated completely, though. You can still hear common road noise and the elements around you, but the level is brought down quite a bit.
If common road noise was at a “level 10” before the sound deadening, I would say it’s about a “level 5” after. The sound is literally cut in half. Deadening the floors also helped improve the audio experience but nowhere near the doors.
If you are looking to cut your road-noise in half, the floors are a must.
#3 – Sound Deadening Hatch
The hatch was the easiest out of the top three. It also pulled everything together. Finishing the rear hatch really took the audio performance to another level.
The bass performance is noticeably tighter with pronounced clarity throughout the highs and midrange. The lows by far see the biggest improvement with deadening though.
The audio improvement was incredibly impressive. It really does sound like an aftermarket system after you deaden the doors, floors and finally, the hatch.
#4 – Sound Deadening Roof
I might at some point deaden the roof but after doing the doors, floors, and rear hatch, I was impressed enough. I also didn’t want to compromise the headliner material.
Every time I have pulled down on the headliner, it literally cracks and causes a crease in the material on the backside. I just didn’t feel like the juice was worth the squeeze for my specific situation with a focus on the tire noise.
If you are looking to go all out for audio performance, it’s probably something you should go for. Or if you are looking to reduce roof rack noise, you may want to consider deading the roof as well.
Just know that you need to remove all pillar plastics, A, B, C, and D (upper and most of the lowers) along with the overhead center console, overhead handles, visors, etc.
Then, you can finally pop all the push clips that secure the headliner into place. I would not try to bend the liner as you may compromise the rigid material our headliners are made of.
The step by step installations are coming next for the doors, floors, and hatch.