they are drum brakes
how do i replace the rear brakes on a 1993 Buick Century? on 1993 Buick Century
The rear drum brakes on a Buick Century are not an easy repair ( I was a GM dealership Journeyman ) You have to get all the springs exactly correct and evaulate all the hardware or they WILL come apart on the road and you will lose you rear brakes. It also takes some strong spring tools. For safety sake, see if you know a GM experienced mechanic and pay him/her for 1-1.5 hours to R&R the brake parts. Your safety is at stake here.
have drums loose, but wont come off, tried to get to adjuster. theres an oblong plug on top left of drum