Exhaust drone with skid plates

I installed the aluminum engine and transmission skid plate with catalytic guard setup from RCI today. I have the TRD exhaust pipe that removes a resonator.




I hopped on I-70 and drove 2.5 hours right after installing the skids today.

The exhaust is significantly louder in the cab, and the drone is way, way louder. It's not to the point of being completely obnoxious, but I didn't expect it to make this much of a difference.

It is trapping the sound/vibration within a few inches of the bottom of the the cab and the skid, where before it was completely open.

Has anyone else noticed this?

 

Check to ensure none of the exhaust pipe is touching the plate.

 

It does look like the catalytic converter might be touching the cat guard.

Hard to tell from this angle.

 

Lots of weird stuff happens with reverberation, im sure something changed when you added a shield.
I don’t drive a lot of highway, but definitely notice the drone magnify under a overpass. One day I’ll get it piped passed the bumper with turn downs.

 

Things can shift a little under load. My guess would also be contact of somekind with the new skid plate VS trapped noise.

 

I noticed no cabin noise change at all after installing a trans skid/cat guard

 

Same brand skids plates?
Maybe the design of said skids plates affects harmonics.

 

There is some slop when installing the RCI skids so you can adjust them to the left or to the right side of the truck to be closer/further from the cats. Something to check in the event there is some contact happening when the truck is actually moving. I’m assuming the cats can also move a little since they are on hangers and those spring flanges.

 

I have the aluminum RCI set as well, I was worried about the possibility of noise bouncing around under there. I have to say that I haven't noticed any additional noise. I have a stock exhaust so that might help. It is pretty quiet all around.

 

It's almost too hot to even breathe, but I'll crawl under it tonight and see if I can shift anything around and make sure all bolts are snug.

The vibration on the floor makes me think it's either contacting the exhaust, or a loose bolt.

I did some searching and found some people have had similar issues on various vehicles that were solved with dynamat.

 

Maybe your exhaust got loose, might want to check that when your check your skid plates.

Are there certain torque specs that must be used?

 

I crawled under the truck last night, loosened the bolts shifted around the plate, and retightened.

The vibration/resonance might be slightly less, but it's still noticeable. I'll need to do some more diagnosis when it's not absurdly hot.

 

Tracking down resonation is a big PIA. Sharing an experience with my 4Runner. Had same issue and spent many hours checking clearance of system. Finally started looking at the heat shields installed over the top of the exhaust system. Started from the engine and working back found the culprit with one of them vibrating from the exhaust resonance over the section going over the rear axle down from the muffler. Did some adjustments adding a couple of rubber grommets and some bending of the ends and this did the trick. Hope this helps

 

I've got the exact same aluminum skids (engine and transmission) as well as the cat guards from RCI. I haven't noticed a difference in the exhaust sound/resonation, but I don't have the TRD exhaust though.