Vibration in front at speeds of 20mph and then again at 40mph, kind of a thump thump noise too. i think its the bearings, but how do i know if its inner or outer or are they all the same parts. 93 chevy lumina 3.1

Could be throw out bearing.

I would have the front wheel bearing adjustment checked first as if they are loose the rotor will be rubbing on the pads and the vibration will be wheel wobbling on the loose bearings Unless you replaced the bearings with new ones then they will fail especially if the adjustment was too tight and too much grease was used.

sounds like wheel bearings-1st
but hopefully your front disc need turning, or replaced.
check wheel bearings by jacking up the front end "CAREFULLY" WITH
JACK STANDS & wiggle tires,if you get more than a 1/4'' slack on 1 or the other, than it's shot. Best to replace both sides. "GOOD LUCK'' &
BE CAREFULL.

I suspect a bad tire.

Why drive side bearing could be a bad other.balance yes, tie rod could be bad.

check front hub/wheel bearings also check brake may have play in fromt pads

You probally have a bad front wheel bearing , when the noise changes when you move the wheel is typical of a bad bearing.this should be covered under your powertrain warr.

I think your right that its a bad bearing or hub. If your feeling it in the gas pedal and the floor, its most likely the front. If you can find an empty parking lot, try to get up to the speed it starts making the noise, and turn left and right. With the extra load being put on each bearing from turning, that will tell you which side it is.

At what speed do you feel the shake and does it only happen when you apply the brakes?

if its more of a whining its your power steering pump.