So...seems like 80mph or above I get this constant deep hum from the lower engine bay, maybe even the tranny. This only happens when Im accelerating lightly or heavy. When it does happen, its usually 80-100 and it stops, or maybe Im to busy concentrating at that speed to notice =P
Im just curious as to what is causing this, because Im assuming if I tell that story to the service dept theyll just laugh because no way in hell are they gonna have a tech reproduce the issue =D

PS No mods and yes, I know what my motor and blower sound like so constructive input only plz

 

Okay Ill ask somebody who actually knows something =P

 

How many miles on the current transmission? A friend of mine had the same thing, it came on so subtle he hardly even noticed. He had the transmission rebuilt and the builder said the main carrier bearings were shot and ready to fall apart.

The next time he drove it, it was quiet and smooth he thought it was the wrong truck.

It is possible that you could have a dry or worn u-joint. If the truck is lowered, you may want to check the pinion angle, that too can cause a humming vibration at speed. Could be the pinion bearing, not uncommon on high torque vehicles, and it could also be a wheel bearing.

That is all I can come up with now given your symptom description.

 

Im on my second tranny, a refurb.
And lowered a cpl inches, Eibach springs.
About 32k on the truck.

 

I am going to lean in the direction of the tranny. Depending on who did the refurb and how many miles were on that tranny, there is a real good chance that what you got was just some new clutches and seals and that the sprague and carrier bearings were not replaced. It could also be in the converter. Did they use your converter or the one from the rebuild?

 

I have no idea. Tranny went a few days after I got it and was replaced with a refurb, I have no further info on it really...but I took out full bumper to bumper and powertrain so I have no issue with dumping it on em again.
Of course, Im gonna soak the rear wheel wells with solvent to get some of that rubber splatter off =D