braking issues

[WARBIRD89]

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I'm having braking issues with my 87 grand national, when you first press the brakes,the in dash brake light will flash for a sec the go out then go out, it takes an extraordinary amount of force,for the first three seconds then the breaks finally react, the system reminds me of what I had on my Thunderbird Turbo 1989 with ABS, is this something that can be fixed or needs to be replaced? I have noticed if you ride around with your foot about one inch on the braking pad, the breaks seem to react much more quickly.(unfortunately brake lights are always on using this method).........(bad master cyl)??

 

[suicide six]

PM may be overserviced,key off pump approx.10 times,check level.If all is well,accumulator is usually the first thing that goes.Always nice to have a spare accumulator and switch.After pumping down brakes and checking fluid level.Turn key to run but dont start car,listen for pump to run,15 secs to 10 secs usually means shot accumulator.Bad accumulator symtoms are usually hard intially w/light.Bad switch is usually hard pedal at all times or pump,PM failure Check 30 amp fuse at box.Long running pump can blow this fuse.Good luck.

 

[jhanson1750]

How long should the PM run with a good accumilator?

 

[suicide six]

Approx 7 to 10 secs.Try a known good accumulator,borrow a friends if possible.Just pump pressure down before removing.Heard Kirbans is selling replacement accumulators again.The diaphrams rupture with age,use.Even new ones can loose charge over time.This brake system has always been a nightmare and can fail at anytime.Some have reported a light brake squeal days,weeks before total failure.When mine went finally,both feet couldnt depress brake pedal.Make sure emergency brake is always in good shape.Many have converted to standard vac brakes due to these failures,overpriced or limited parts.Usually hard pedal on all applies are caused by switch,pump failures.Momentary hard pedal is usually acc low charge and or internal/external leakagefrom my experiance