As far as the shaking, be sure to have the wheels blanced properly. If the balance is ok, then it could be a bent wheel, or a bad tire. To adjust the rear drums, you will need to take off the drum, and at the bottom of the assembly, there is an adjuster wheel with little spikes on it. You need to turn this little wheel to expand the brake shoes outward some to take up slack. Adjust the little wheel in small incraments then put the drum back on. When the adjustment is right, you should feel a very slight drag on the drum while turning it with your hand. Do the same for the other side, and your set. When i did this to mine, i noticed a big difference in stopping power. I could tell that the rears were helping in the braking, and before i could tell that the fronts were doing all of the braking. The rear drum brakes should adjust themselves for wear, but they usually only do that when you make a good hard stop in reverse, which many don't even do very often. I try to make a habbit of doing a hard reverse stop at least every other day, and it seems to be working good so far, i haven't noticed any braking loss yet..