hi. I ran into this before. first thing is do you have drum all the way around? do you have frt disc and rear drum? or do you have disc all the way around? first thing that you have to check is rear brk adjustment, it must be adusted right. put a very slight drag on it ifyou have drums. if you have disc's then the free wheel gap must be very slight to the rotor when right.same for the front. the rear may or may not have the e-brake built into the caliper, if it is in the caliper the ratching internal parts have to work properly or the gap will not adjust the space between the rotor and the pad surface which will give you the problem that you are having. next is the lenght of the rod that is between the m\c and the booster, must not have any pressure on thr m\c or things get bad in a hurry.hope that this helps you alittle. good luck dave