On Tue, 8 Oct 2013 14:40:59 -0700 (PDT), wrote:

On Monday, October 7, 2013 10:08:54 PM UTC-4, 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

In the could-also-be-in-addition-to-what's-been-mentioned department...

Depending on the pickup, if it has a 2-piece driveshaft with a carrier the carrier bearing could be shot, or just the rubber supporting he carrier could be shot. Usually midsize pickups are the biggest with this arrangement, so probably not relevant.

Could also be a worn out slider (where it fits into the trans with a 1-piece shaft), or just bad output bearings in the trans.

Dave
Or a bad trans mount. Again - what year, make, and model???