Rear Quarter Panel Sound Deadening Using Noico 80 mil Black: Installation & Walkthrough

How To Sound Dead The Quarter Panels on a 5th Gen 4Runner – Overview & Everything You Need to Know

4Runners are not known to have the quietest cabins in the industry. While this may not be a deal-breaker for both prospective and current owners, any improvement in this area is greatly appreciated.

To accomplish this, I followed this article on how to install sound deadening throughout the cabin using 3 boxes of Noico 80 mil Black (36 sq ft kit). It took about 2 days in total to complete; side doors on the first day and the hatch and floor on the following day. As Brenan stated in the article, the road noise has been reduced to about 50%.

Why I Install on Rear Quarter Panels?

Recently, due to uneven wear on one of the rear tires (Goodyear Wrangler Duratrac 265/70R17), tire noise became very loud when driving at speeds over 40 mph. Since I only have just about 30,000 miles on the tires, I didn’t want to change them yet.

Since I still had some sound deadening sheets leftover from the doors and cabin installation, I decided to sound deaden the rear quarter panel area as well. Also, I am interested in installing a custom subwoofer box in the factory location of the trunk, so I wanted to apply sound deadening material there and to get an idea of the space.

There are some videos on how to remove the rear quarter panel but I decided to create a more detailed article with high-resolution images and tips that I’ve learned.

Materials

You can choose whichever sound deadening material; the thicker, the better. I used little less than four 29.5×19.5 inch sheets to cover the left and right rear cargo area.

• Dynamat 67 mil (1.7 mm): Check Price
• Noico 80 mil (2 mm): Check Price

Tools

• Phillips head driver
• 8 mm, 10 mm, 12 mm, and 14 mm sockets
• Roller
• Scissors
• Utility knife
• Plastic pry tools (expired credit card also works)

Installation

Before you begin: Remove the cargo tray and compartment (or third-row seats), and rear back seats

For removal of cargo tray and compartments and rear seats, follow this post (skip to “Sound Deadening Floors”). For the removal of third-row seats, follow this video. You don’t need to remove the rear bench, just keep them folded.

Step 1. Remove caps and bolts

We’ll start from the left side since it’s easier as the right side has connectors for the power outlets and requires a little extra work.

Start by twisting off the cargo hook (green circle) to reveal a Phillips head screw. Apply a plastic pry tool on the bottom part of the circular plastic covers (orange circles) to reveal two 10 mm bolts. Remove the cargo tray bracket (yellow circle) to reveal a 10 mm bolt. With all caps removed, remove these five bolts and keep them safe.

Repeat the steps above to reveal and remove the bolts on the right side of the cargo area. On the right side, we’ll also take off the 14 mm bolt holding the rear seat bracket (red circle, far left).

Step 2. Remove rear seat belt bolt and rear-seat recliner handle

Start by removing the plastic cover by inserting a pry tool from the bottom and lifting it up.

Insert two plastic pry tools on the side of the rear seat recliner handle (two locations, near the back of the two arrows) and pull towards the passenger side in the direction of the arrow (study the following photo if you are still confused). Next, remove the 14 mm bolt securing the seat belt.

Here you can see where the two clips are on the left side of the rear seat recliner handle.

There are two 12 mm bolts under the seat recliner handle, remove them as well.

Step 3. Remove rear kick panel

Pull straight up to remove the kick panel. You can insert a pry tool from the outside and wedge it up if needed.

Step 4. Remove driver side rear quarter panel

Starting from the rear bottom, pull out the panel towards the passenger side, one clip at a time. White push clips (same as the ones on the kick panel) are marked with yellow circles. Use a plastic pry tool on parts marked with red circles to pry off the plastic teeth, working your way across the top edge towards the rear door. Partially pull off the rubber rear door weather liner covering the panel. At the panel edge (marked with an orange circle), gently pull the edge towards the front of the vehicle to unclip the plastic tooth.

Adjust the rear seat bracket angle so that the bracket clears the panel opening. Pull the final push clip off (marked with a yellow circle) by pulling on the panel towards the passenger side. The panel should be off if you removed all the bolts. If not, check that you removed all the bolts in the previous steps.

Step 5. Remove seat reclining rail and rear seat belt

Now that the panel is off, you can clear off the wheel well area to apply sound deadening material. Start by removing the 8 mm bolt (center top) and two 14 mm bolts securing the rear seat reclining rail. Then, you’ll have access to remove two bolts securing the rear seat belt (12 mm top, 14 mm bottom).

Step 6. Remove passenger side rear quarter panel

Follow the same process as you did on the driver’s side, starting from the rear bottom, working your way up and towards the rear door. Be careful not to pull off the panel too much. Before completely pulling off the panel, reach in from the rear door end to disconnect two couplers for the power outlet and the cigarette socket. Then, the passenger side rear quarter panels can come off.

Step 7. Remove seat reclining rail and rear seat belt

Remove two 14 mm bolts securing the rail. There are also another two bolts (12 mm top and 14 mm bottom) securing the rear seat belt that needs to be removed.

Step 8. Remove the inverter and factory subwoofer box

The inverter for the power outlet and cigar socket is secured with three 10 mm bolts. If you have one, the factory subwoofer box is secured with four bolts. Now that the area is clear, we can start to apply the sound deadening sheets.

Step 9. Apply sound deadening sheets

My tip is to first apply the sound deadening sheets on areas with large flat surfaces. To check if a surface section needs to be covered, knock on the panel. If it sounds light, cover it with sound deadening. If it sounds deep or dull, then you might not need to cover that area. I thoroughly covered the wheel well to reduce the tire noise that I was experiencing.

Step 10. Reinstall quarter panels

Before reinstalling the rear cargo panels, double-check that you secured all of the bolts for the rear seat belts, rear seat recliners, an inverter, and a subwoofer box if you had one.

Tip: Remove the two Phillips head screws (circled above) and pop off the tray on the rear quarter panels. This way, it is easier to reconnect the inverter couplers and also utilize this negative space between the wheel well and the panel. If you added the factory subwoofer box (PTR8615035080), also remove 14 screws securing the utility cavity on the panel.

I hear some people have trouble reinstalling the panels, so here are some tips. From the rear door side, make sure to align the panel on the top edge,

There is a white plastic clip that aligns with a hole in the body, as shown above.

The rear seat recliner handle comes out from the opening,

Finally, align the white plastic clip on the bottom of the panel. Now, you are ready to clip the panel back on, starting from the bottom, working your way up to the rear hatch.

Reinstall the two screws inside the rear seat recliner handle. Then, reinstall the handle by sliding it in the direction of the arrow.

It is now easy to reattach the power inverter wire harnesses to the panel.

Final Thoughts

It took about 8 hours in total to disassemble the rear cargo area, apply sound deadening material to the rear tire well and quarter panels, and full reassembly. Before the mod, it was embarrassing to let others on the truck due to tire humming. Now, the noise is reduced by about 50% and doesn’t stand out as much.

This mod will also help with the sound quality of the subwoofer if your 4Runner is equipped with one in the factory location. If you have some material leftover as I did, I would definitely recommend installing rear quarter panel sound deadening as well.