89 240 DL wagon- 1 ½ year old rear brakes, calipers and discs. Pass side pads almost totally gone, one pad rusted in place and one pin rusted in place. (northern car, got it all apart) other side looks like pads are minimally worn. Bad pulse of pedal before and after new front discs. Any thoughts? THANK YOU!

 

If the brakes pulsate and shake the steering wheel, then it's front. If the whole car shakes or pulses, inspect the rear brakes.

Also, I have gotten new rotors that were warped right out of the box especially from Napa.

 

The side minimally worn probably has a frozen caliper. Shake can be caused by bad rear rotors as well.

 

OK i've got one rebuilt warranted rear caliper, new set of pads and two new rotors. Only one last question and I might have to inquire at NAPA, on the old caliper, I was able to push the outer piston in by hand, but couldnt budge the inner one (trying to fit new pads to the still functional caliper) Does the inner piston screw out instead of just coming out? Thanks again! Dave