Grumble noise at 30-50

[lcducote]

im getting a grumbly noise under my feet at 30-50 mph... always at 30 regardless of rpm. the duration of the noise varies.. sometimes it goes till 50 and others just to 40. please help if you can. it kinda bothers me

[Dudenhymer]

Sounds exactly like what I have going on. Mine happens more when I'm turning slightly left i think around turns. I found out what it was thanks to a suggestion form another board member.
Check to make sure your exhaust isnt hitting the frame just after it drops down to the bottom of the truck near tha hanger. I've got a 4" system too xept mine is Flowmaster and that what is causing the rumble on mine. I fixed it a couple of times using a pipe clamp around the hanger to pull the exhaust up higher, but the clamp keeps coming off when I take it offroad.
If you find you have the same issue and get a good fix going then let me know.

Good Luck

[lcducote]

i already have moved the exhaust and im still hearing and feelin it. ??? idk

[kitchene]

i get a grumble sometimes when I let off the accelerator over 40 MPH.

[lcducote]

yall arent helping hahaha

[ridiculously_necessary]

mine does this when stopping, reverse or hard turn. mounts are ok, i came to the conclusion that its the DP hitting the firewall. i have an OBS though, not sure hwo close the DP is on an SD...

could it be a tire out of balance?

[Dudenhymer]

Ya, I bet it's your exhaust hitting somewhere under the truck. Trace that bad boy out.

[lcducote]

i have removed and re-mounted the exhaust.. i mean there is very little room between the DP and the firewall.. i suppose that could be it. i mean i can fit a couple pieces of paper between them haha