[QUOTE=Adams' Apple]If it is
RPM dependent, it will be engine/flywheel related.
If it is
speed(mph) dependent, it will be driveshaft/halfshaft/tire related.
Usually, engine or flywheel vibrations are constant, meaning it's always there, just worse at certain rpms. You can also get the vibration without the car moving, if you raise the rpms.
Driveshaft/tire, or "speed" dependent vibrations can come and go at different speeds, and may get worse, or better at times. This type of vibration will only happen while the car is moving.
You say it "comes and goes every 1/4 second"...1/4 second???
You've got a good sense of timing if you can count that fast!
From your description, I'd say start looking at the driveline first.
[/QUOTE] Adam, I'm hurt!! You know I work in the Aerospace ind. I can count things in my head into the thousandth's and won't be off but a tick. LOL!!!!. Really, I can see in my reivew- mirror the comming and going of the vib. it gets clear and vib. back and forth in less then a second interival. I'll check without a load and see if it's still there.