Problem with my brakes on my 1982 Oldsmobile Toronado. Please help!

[battlecat]

My 1982 Oldsmobile Toronado (about 138,000 miles) has been having some braking issues for a couple years (it gets driven sporadically). When I come to a stop, the pedal would feel fairly normal initially, then as the car slows to a stop, the pedal "fades" (suddenly sinks about an inch, then "firms up" again...simultaneously, the car would (for a split second) have decreased braking, then would return to normal. This hasn't bothered me too much (figured it was due to an old/worn power brake
booster); however, recently, while coming to a slow stop at my driveway, the pedal became hard and the car wouldn't stop...so I pushed even harder...I heard a "clunk" sound, then the pedal worked...the car stopped...but the dashboard "brake" light came on for a brief second (Note: this doesn't seem like a worn Master Cylinder...because the pedal will "firm up" eventually...and not continue to fade all the way to the floor the way a worn master cylinder problem would do) When I parked in my driveway, I checked the fluid...it was okay. I'm thinking this may still be a problem with the power brake booster...but I'm not sure...does anyone have an idea what this might be?

[maxwedge]

This is usually not a diagnosis over the internet, yes the booster could be at fault, so could sticking calipers, the rear were always problematic, so could the proportioning valve, especailly if the fluid has not been changed, water accumulates and rust can form throughout the system. Confirm good vacuum to the booster, also check the check valve at the booster, then the system must be gone thru for additional checks.

[battlecat]

Originally Posted by maxwedge

This is usually not a diagnosis over the internet, yes the booster could be at fault, so could sticking calipers, the rear were always problematic, so could the proportioning valve, especailly if the fluid has not been changed, water accumulates and rust can form throughout the system. Confirm good vacuum to the booster, also check the check valve at the booster, then the system must be gone thru for additional checks.

Thanks, Maxwedge! You've given me some ideas I can pursue...I'll let you know what I come up with!