soft brakes, pulsating pedal... solved

[Konstantin Bogach]

Patient is 200tqa '89. Diagnose: bomb is bad (no pumps required before
pedal becomes hard), brakes are soft, never changed anything brakes
related since I bought the car 2 years ago.  No,  I am lying. I changed
MC when I bought it. I noticed that when I step on brakes while idling
pedal stops fist where it's supposed to stop, I think, when brakes are
good,  then it goes down more with  pulsation.  No "bad brakes" warning
(I remember someone posted  this too).

I rebuild calipers, front and rear, put new rotors/pads, bled thoroughly
- soft brakes, pulsation stays.   It seemed to me that rears worked not
well enough, so I removed proportioning valve and cleaned it.  I has
some gum inside and could stick.  It helped but not much.  Bit a bullet
- treated the car with  new bomb (did not get a reply from Russ
Southerlin) and brakes became normal, no pulsations.  Had I known  that
main culprit is the bomb I could drive 2 more years with old rotors/pads
and postpone calipers job.

Finally installed filter for hydraulic system from James Marriott which
I bought long time ago.  Anybody went that far?  Any interesting
observations?  I will post if I notice anything worthy to report.

Best regards to all,
Konstantin Bogach
200tq '89
200tqa '89 (finally with good brakes)
UrS4 '93