On Mon, 7 Oct 2013 22:20:59 -0500, "Snag" wrote:

Ignoramus3720 wrote:
I have a problem that I noticed with my pick-up truck.

The problem is that at certain speeds, such as 40-45 MPH, I feel
vibration if I step on the gas pedal and try to accelerate. If I let
go of the gas pedal, vibration stops even as the truck continues to
drive forward. It has gotten worse lately. I have thought a lot on
what could cause it. It does not seem to be related to the engine
RPM. I watch the RPM vary and the vibration does not vary with it.

What could it be?

i


Could be u-joints . Easy to check - put the parking brake on , gear shift
in neutral . Might want to chock the wheels , I don't usually . Slide under
the truck and rotate/shake the driveline . If you see movement in the joint
it's shot .
It can be shot with no appreciable looseness. The joint can be tight
instead of loose and still cause a shake. Generally these squeak, or
"chirp"