Front brakes works, Rear brakes not so much on 2002 Chevrolet Prizm

Recently my mechanic changed my rear brakes. He noticed that the rear brakes does not fully engage when pedal was pressed, meaning when the brake pedals were fully pressed, one can still turn the rear wheel using some effort (hard to turn, but still moves when turned by both hands). At the time, rear wheel was jacked up & I read about "pressure modulator" on rear wheel which reduces pressure directed to rear wheel when there is less weight on the wheel. Could it be my problem?
One more thing, now when I hit the brakes, passenger side rear wheel make a sound like "Tuck, Tuck, Tuck" as something hitting against another thing. My mechanic says its the brake shoes, because they go only half way towards drum. His solution is to replace the Master Cylinder. Would that works...appreciate any advice and thanks in advance!

Asked by for the 2002 Chevrolet Prizm
My questions would be why did your mechanic let you leave the shop with rear brakes that don't work? He didn't really do that, did he?

I would recommend going elsewhere for a second opinion. It's possible that it's the master cylinder, certainly, but it could be another component, or components.
I honestly don't know about the pressure modulator--not enough to comment for you. If the brakes were successfully bled, then you are right--the hoses are not clogged. The master cylinder is the source of that hydraulic pressure, so that is a place to look for a problem.

It's true that the rear brakes do much less work than the front, in all cars, but they still need to work 100% before letting a driver back into their car and out onto the streets!! Good luck!
Hi Matte,
Thanx for the reply
Yes definitely I am going to get a second opinion from another place...but I was curios abt the "Pressure Modulator" there a part like that does what I read (easing up pressure based on weight on the wheel)? BTW I was told by several people that in small cars like Chevy Prizm (mine), the front brakes does most of the work.
If I can ask 1 more question from you, if the brake fluid bleeds when done so, that means my hydraulic pipes/hoses are ok (not clogged) right? The reason is, to me it seems there is not enough hydraulic pressure reach the wheel cylinder..but I'm not sure
1 more answer
Your brake guys are ignorant or you are really cheap