Problem with brakes in 1989 88

Hey, Ive got a problem with my brakes. When I first got the car a couple weeks ago, the brakes were fine, would be firm until the car stopped. But the last two days whenever I apply the brakes, it gets about 2/3's down and then I hear a clunk and the pedal jiggles. The brakes work fine(I can still stop fast if I want)but every couple brakes the brake pedal does the thing where I will be applying pressure and then it makes a clunk....

What do you mean by the pedal jiggles? Does it go from firm to really hard to frim to hard again? Or does it vibrate? Or ?

What color is your fluid? It should be a nice light brown color. Also, what kind of shape are your rear shoes and springs in? Where are you hearing the clunk from, the rear of the car, towards the front, or from the engine bay?

Off the top of my head, I would suspect either a broken spring in the rear drums, worn shoes, or a faulty brake booster, but more info would be nice.

I havent looked at the fluid, but when I brake, the pedal will be moving down, and then the pedal loses its firmness for a split second, and then continues going down firmly. During the split second it does that I still have brakes, but unfortunatly I cant tell where the thump(its very quiet)is coming from. The pedal also kicks back a little bit, but not much.

Interesting... Possibly a vacuum problem with the brake booster. Does this car have ABS? I hope not for your sake...

However, musyness is usually related to the master cylander. Is any fluid weeping out where the MC and the BB are bolted together?

the brakes seem to have problems when Im going about 70mph and try to slow down. When I push on the brake it starts going thump thump thump(about 2 times a second) until i push hard on the brakes(once I get below 20mph) and then it stops(the thumping stops)...the brakes seem to work fine, but they make the thump(which can be felt in the pedal and heard)

Pull the rear brake drums and look for problems there.

Yeah, pull the drums and see what kind of shape your shoes and springs are in.

I wonder if a bad ABS wheel sensor could cause this? I hate the early ABS systems....

hmm i have some problem like that to... only in the morning tho the brake makes like a thump sound and if im lucky enough to push down the brake pedal i can feel it in the pedal it pushes it back up slighty and vibrates its kinda weird but yeah im used to it....