What is this intermittent booming noise coming from the back?

[Jeffjad]

I have a Limited with is the full size cab.
If you have not heard a drumming noise you may want to bow out of this thread now before you begin to notice it.
I purposely don't read problem threads when the issue in the thread title is something i haven't experienced. It may open my eyes to something I just hadn't noticed before, you know?

I think it would be hard to record the noise with a cell phone. I can try though.
If you really want to chase this issue drive at 39mph with all windows up and listen for booming in the rear.

Def not chasing any issues I don't have, just trying to help a fellow RAM driver by process of elimination. Good luck hope you guys figure it out.

 

[MaximumEffort]

I have a Limited with is the full size cab.
If you have not heard a drumming noise you may want to bow out of this thread now before you begin to notice it.
I purposely don't read problem threads when the issue in the thread title is something i haven't experienced. It may open my eyes to something I just hadn't noticed before, you know?

I think it would be hard to record the noise with a cell phone. I can try though.
If you really want to chase this issue drive at 39mph with all windows up and listen for booming in the rear.

This drove me nuts when I first got my Limited. Pretty much spot on at 39/40 MPH I would hear this drone in the cabin. +/- 1MPH from there and the drone goes away. I started using the drone noise to tell me when I was doing 40 MPH without having to look at the speedometer.

 

[Buz]

This drove me nuts when I first got my Limited. Pretty much spot on at 39/40 MPH I would hear this drone in the cabin. +/- 1MPH from there and the drone goes away. I started using the drone noise to tell me when I was doing 40 MPH without having to look at the speedometer.

How’d you fix it?

 

[MaximumEffort]

How’d you fix it?

I have not done anything to address it. It has diminished over time.

Sent from my SM-N960U using Tapatalk

 

[JGRaider]

Crew cab here, Laramie version, and I have same issues under same conditions as Buz.

 

[Jimmy07]

Great Idea.
If its wedged in there tight enough right above the vents maybe it will stop the back wall from vibrating like a drum causing the noise.

Pull the molded insulated panel off the back wall, and stick patches of 80 mil sound deadening mat to the sheet metal. It doesn’t take much. This is how we fixed the same issue on the 4th gens.

 

[Buz]

Pull the molded insulated panel off the back wall, and stick patches of 80 mil sound deadening mat to the sheet metal. It doesn’t take much. This is how we fixed the same issue on the 4th gens.

Interesting.
The 4th gen had the same booming noise in the back?
Was it tied to the vent flaps opening and closing rapidly at certain speeds?

 

[Buz]

A pool noodle might work pretty well

Took a noodle and had to cut off about a quarter of it lengthwise to be able to stuff it down between the cab and bed. Got it smooshed down to where it's touching the top of the vents. So far I would say it's helping but not completely fixing it. Too soon to tell but yes it's better. Thanks for the tip.
Someone else is saying to stick sound deadening pads on the back wall too.

 

[Jimmy07]

Interesting.
The 4th gen had the same booming noise in the back?
Was it tied to the vent flaps opening and closing rapidly at certain speeds?

Yes. I had it on mine, and several others reported the same issue. I wouldn’t describe it as a “booming noise”, but more of a “thud”.

 

[Buz]

Update for anyone having this issue.
I added about four square feet of 80mil sound deadening material to the back wall of the cab last week. Got the material online for about $14.
The sound deadening material combined with the pool noodle stuffed between the body and bed has eliminated 80% of the booming phenomena.. It is not nearly as obvious as it was anymore and I can live with it now. Glad to not have to complain about this anymore.

 

[Vinnie.]

Took a noodle and had to cut off about a quarter of it lengthwise to be able to stuff it down between the cab and bed. Got it smooshed down to where it's touching the top of the vents. So far I would say it's helping but not completely fixing it. Too soon to tell but yes it's better. Thanks for the tip.
Someone else is saying to stick sound deadening pads on the back wall too.

i just took delivery of my 2021, and it seems there is a rubber strip between cab and bed. i'm wondering if this is new to help with this issue? originally was there nothing there on your truck?

 

[Dirtdoc]

Have exact same issue. 21 limited crew cab and of course air suspension. Put a bedrug in box, switched tires and different air pressures. Crawled underneath to see if anything loose. I drive usually in silence also and notice it at same speeds. Would like to fix also. Do you have any pics of what you did? My 2018 longhorn did not do this. Thanks for figuring this out.

 

[Neurobit]

You guys sure this is not MDS?
Try putting in int Tow/Haul and see what happens (T/H disables MDS for those that don't know).

Cheers,

 

[Buz]

It's not MDS. It's the back cab wall vibrating due to air pressure causing the vents on the back wall to 'flutter', or open and close rapidly at around 39mph.
I have the rubber seal between the cab/bed. That does not fix the noise.
The combination of the noodle and me adding about 4sf of sound deadener on the back wall has all but eliminated it. I don't hear/experience it anymore.
Just be careful not to cover the vents when you shove a noodle in between the bed/cab.

 

[Neurobit]

It's not MDS. It's the back cab wall vibrating due to air pressure causing the vents on the back wall to 'flutter', or open and close rapidly at around 39mph.
I have the rubber seal between the cab/bed. That does not fix the noise.
The combination of the noodle and me adding about 4sf of sound deadener on the back wall has all but eliminated it. I don't hear/experience it anymore.
Just be careful not to cover the vents when you shove a noodle in between the bed/cab.

Got it. Thanks.

 

[c3k]

Couple of thoughts:
1. The sound deadening material on the back wall is a good idea.
2. Add a weight to the flaps to change their frequency?
3. Cut a small notch in the flaps to allow more air when they are closed?

 

[Buz]

Couple of thoughts:
1. The sound deadening material on the back wall is a good idea.
2. Add a weight to the flaps to change their frequency?
3. Cut a small notch in the flaps to allow more air when they are closed?

Agree with #1. It played a big part in getting rid of the drumming noise.
No on #2. The flaps are literally paper-light. I wouldn't touch them.
No on #3. I don't think a small notch would do anything. You pretty much would have to remove them, which opens up new can's of worms.

 

[Jimmy07]

Couple of thoughts:
1. The sound deadening material on the back wall is a good idea.
2. Add a weight to the flaps to change their frequency?
3. Cut a small notch in the flaps to allow more air when they are closed?

You definitely don’t want to impede/add weight to the flaps. Then you’ll be getting into cabin pressure issues where you’ll find yourself possibly having to slam the doors to get them to latch closed.

 

[HarryW]

2021 Ram Bighorn crew cab I have a similar sound on road seams and bumps. I said it sounded like a bass drum. Is this the sound you folks are hearing? I was going to play with tire pressures but it sounds like this is not new. I have had this sound form the beginning but have yet to complain to the dealer. Is there a service bulletin related to this?

 

[Ari K]

Hello,

I think I have this same issue in my 2019 limited. Also think that its on this video I found

Quite slow speed, railroad rails or something like that and it first really sounded that something is wrong with suspension. Now I think its those flaps.

Any luck with repairing this?

Ari