Ok so I've got this weird noise around 1750 to 2000 rpms. It occurs under light throttle during each shift. The sound is best described and as vibrating tin sound. Kind of like a rattling heat sheild. I have checked all my exhaust clearances and even the debris sheild on the torque converter access. I can only produce the sound under light throttle loads with soft shifts. When I accelerate moderate to hard, there is no sound. Could it be a bad torque converter or the clutches rattling. I am baffled. The transmission shifts fine and pulls good (other than having 3.55s with 33" BFGs). Any input would be appreciated.

 

Heat shield on the cat?

The cat itself?

Loose bolt somewhere?

Also, have a look at your trans lines, make sure they are secured good. They just might be vibrating from the 'right' pressure on light throttle shifts.

 

Well it definately has to be the transmission. When I rev the engine just around 2000 rpms, I can definately hear that vibrating sound.

 

you sure it's not comin from the engine? can you get someone to rev it a little in park while you are under it listening for the noise?

I'm also inclined to say it's a rattling cat at this point in time... get under there and beat on it to see if the contents are broken up inside...

 

yeah I agree....if it was your tranny it wouldnt do it at the same rpms uless it was always while you were in the same gear at same speed and rpm.... sounds like the engine harmonics at 2000 rpm is causing something to vibrate...usually this is the cat heat shield on top of the cat as previously mentioned but could be other things like a bad universal (more like a vibration than rattle though) or a loose exhaust hanger causing pipe to rattle....maybe even a heat shield on motor or exhaust manifold? could even be a bad bearing or gears in the differential..or out of balance tire? does the whole truck vibrate?