Road Noise from rear cab vents..?

kevin

I am sure many of us will be watching your efforts with much interest. Come warmer weather I will be doing some myself. First will be tightening the fit of the vents, and perhaps simply just stuffing the snot out of the space between cab wall and panel.

 

Dynamat works by adding weight and changing the resonance frequency. For rattles Atleast. For deadening and blocking any material you add on top of or in front of especially a material that allows minimal sound transmission, and pass threw is going to help your cause.

The weight of the dynamat changes the frequency of which the metal/ material it's attached to, can resonate (vibrate) at. The material Toyota uses, are to help sound from passing threw it.

Dynamat extreme for instance uses a butyl rubber on one side, this helps block sound waves while giving it an adhesive quality. Then the top layer is a aluminum alloy to reflect sound already inside the Vehicle. The original stuff is more of a factory type of deadening style system. Achieving similar results just using a different type of material. That material absorbs more sound then it reflects. This would be a better application for trying to dampening outside sound from drowning the cab out. Where the extreme is better for boosting audio enhancement.

Dynamat however would only be good to line the wall with, not to block the vents. Maybe some roxul insulation stuff inside the vent would be best. This is a very good insulation used inside homes for sound deadening and insulating. A lot more dense and ridged than the "pink" stuff

 

Yep, that Roxul looks to be a good choice. Spray adhesive on the back panel then stick this stuff all over.

http://www.homedepot.com/p/Roxul-Sa...e-Wool-Insulation-12-Roll-RXSS31525/202531875

 

I wonder if you're hearing road noise coming in from what's known as the "1/4 vent". That's a vent, typically in the lower, rear quarter of the vehicle (hence the name) that allows the cabin pressure to quickly equalize when you shut a door, roll up a window or turn on the HAVC system. It has rubber flaps that operate in only one direction. In a car that vent is almost always in the trunk. But in a truck it would be in the cabin.....possibly making it louder.

 

That's what I was talking about and thought that's what those vents in the center of the cab were. Seemed strange to to a bit because I usually thought those were in the lower quarter. The flaps on those are very thin and any sound will penetrate right through those. I would just apply a little insulation down in the lower c pillar of that's where they are located. Air movement should still be able to open the flap but it will help deaden the sound. Might have to tinker with it a bit to find the "sweet spot" as one of insulations purposes is to try and stop air movement.

I just thought they came up with a more ridged vent back there and moved them to the center of the cab. Wonder what the purpose of those vents are then?

 

Are we saying that there are additional vents (in addition the the rear ones) in the lower quarter panels? Is this verified? On both
acess and double cab?

 

If you seal up those rear vents you'll notice a big pressure change every time you turn on the heat or a/c, which I learned the hard way and had to go back in there and unseal them. I ended up covering the whole back wall with Mass Loaded Vinyl, which is just a very dense, heavy vinyl designed for the purpose of blocking sound. It's about 1/4 inch thick and not very easy to work with but it is an excellent noise barrier. There's still plenty of room for air to flow around the vinyl but road noise from the outlet vent is effectively blocked. Dynamat and other similar materials are good for stopping vibration, which also reduces noise, but in order to block noise you need a dense barrier, the denser the better. House insulation won't effectively block noise.

 

I'm not familiar with how the '16 vents cabin pressure. I just know that in most cars it's in one of the lower quarter panels. From the picture, it looks like they are in the rear firewall in the '16 Taco. I've not check my '15 DCSB...but I can tell you that those vents were not present in either of my regular cabs ('09 and '13)....meaning the vent was somewhere else.

 

Sounds like those are the pressure vents in the '16 Taco. If so...you don't want to plug them up. Your eardrums will not like you!

 

After I sprayed the rear wall of the cab.. I sealed around those lose-fitting vents and then I added a layer of foam from an old life jacket over them... the air will still move out, as it supposed to, but may limit some noise from coming back in... I'm happy....

 

No just the two in the rear panel. There are no vents on the rear side panels of the Access cab at least.

 

I decided to go pro a short video. Apologies for it being a bit grainy. However here is what I noticed:

The vent is divided into 4 channel pairs. A 1/8 (guess) thick piece of rubber hangs freely from the top of the channel.

When I turned on the fan, the rubber was pushed back into an open position.
When I turned on the defrost, the rubber opened fully.
When I closed the door the rubber opened briefly.

What I did find interesting is that because the rubber is hanging freely, it is affected by inertia.
When I accelerated, the rubber opened.
When I hit bumps, the rubber opened.
When I turned the rubber opened.

What surprised me most was when I turned on the fan and chose recirculation mode, the rubber was pulled shut. I was impressed with how much quieter the cabin was. I will try ricirc mode as part of my sound testing.

**Remember I don't have back panels on, so I am assuming that my situation is more dynamic than others. **

Here is a 1.5 minute video showing the vent in action. Please note that my speaking was only for my notes and not to share. I added some text where needed. https://youtu.be/GKBPycp4di4

 

That video explains a lot.
My 2006 Access cab was so much quieter, but on the 2016, definitely hear tons of road noise from the back, and now we know why. We know why we need this, but looks like Toyota went way overboard with the design.

 

I don't notice much difference if any with the recirc on or off in my instance. Or the seats up or down (access cab). Thinking that perhaps the vents do not ever close fully in my situation. Only checking with panel off will tell for sure.

 

It makes sense that the flaps would close with the recirculation on. The pressure in the cabin would be static and maybe even slightly negative at that point.

 

I have the same issue. What I was thinking of doing is either adding Dynomat to the rubber flaps. This will make them heavier and in theory stay closed easier. This may cause then to be ripped off being heavier.

Or replace the current thin OEM rubber flaps with a heavier rubber material that would lay flat on the vents just like the OEM ones does. These would also stay closed easier and would open when a door is closed of recirc is turned off.

Thoughts?

 

Il, try a couple more photos of the vent. Interesting you can pull them off from inside the cab. I can't figure out how to remove them. Depending on the distance between the cab and bed, you may be able to inspect/ change from there

 

When I was messing with my vents, I tried to remove then from the inside....NO GO..!! Looks like you gotta remove the box..!

I pushed the tabs and slid the vent to the rear, but could not get it thru the hole to the inside...!!

 

I'm sure they were installed at the factory when the bed was off.

I think the heavier material will prevent quick equalization of cabin pressure...when a door it shut, window rolled up or HVAC fan tuned on. Toyota has been using this type of flap material since the stone-age for a reason....it works....albeit a bit noisily in the '16.

 

What would a slower eq of cabin pressure cause?