When the car rolls in both forward and reverse, there is a very loud grinding/squealing noise that comes from the rear end accompanied by a jerk like the rear end is locking up. I just changed out the brakes to see if that was it, but it is just as loud as ever. Also, the wheel on the passenger side feels wobbly when I jacked it up, but the driver side wheel wasn't that way and I feel as though the noise is coming from the passenger side. A friend of mine told me that it may be a rotor bearing out or maybe the universal joint. Please help.
There shouldn't be any movement in the rear wheels bearings at all. If you have grinding and movement in the bearing then it should be changed as soon as possible.
The universal joint will be a squeaking noise sometimes accompanied with a vibration that is usually speed sensitive.
The wheel bearing can be checked by swerving the car from one side of the road to the other. Find a road that is not busy and drive at a controlled speed.
Swerve from one side of the road to the other. If the noise pitch changes on one turn (left or right) and not the other then it will usually confirm a wheel bearing malfunction.
Usually the pitch will be the loudest on the turn that the weight is shifted to the heaviest side ( swerve left the weight will be the heaviest on the right and reversed on the left).