Archived Brake pedal goes to floor - EEK

[Joe Mc]

Replaced M-cyl w/new (w/resivoir) two weeks ago, bench bled and bled system. Was good for a few days. Yesterday replaced (w/new) front rotors, pads & bearing assys (ouch $210 ea. ). Been fighting a front end shimmy thing for abt a year and have replaced upper lower ball joints, drag link, pitman arm links and track bar so figured I couldn't hurt anything other than my pocket $$$ . . . again. Replaced the proportioning valve as I thought I was taking in air from it - due to wet under the rubber cover. Had replaced the front brake hoses 50k ago (still like new) and yesterday along wlrest I did the back hose. All metal lines are good - replaced one from frame to rear load sensing valve. Adjusted rear shoes up so I hear a consistant drag and the e-brake works great. Bled the system - again - lot of air from the rear set (of course) and get in start it up, pedal goes 3/4 way down and Brake & ABS lights are on.



What am I missing other than about $800 in parts? Should I have the system power bled??? I'm at wits end here and the wife ain't too happy about the $$$ I've spent trying to get it squared away either :-{}



HELP!:{ :{ :{

 

[mberry]

It's been my experience that what you are describing with the pedal is normal after bleeding the brakes. It also sounds like (don't quote me on this) that your rear wheel cylinders are not sealing properly. Sounds like you may need to replace the parts on the rear wheel cylinders. It might be time to upgrade them to 3500 wheel cylinders with new parts. I don't honestly remember if the rears are disc or drum on a 99 but I think they are drums. You've thrown enough money at them to narrow it down.

 

[Joe Mc]

High and Hard - again ... The final story???

I finally got it around 10:30 tonight, pedal is high and hard. Oo. How long will be the test .



Just a ton of air in the back system - again. Never had this problem before and I've done a good deal of brake work over the years on this truck. New calipers (lifetime) 3 times, new front hoses (5 years ago), changed the rear cyl to GMC 3500 (2 years ago - original ones were fine @ 140k just changed to upgrade) and I never before had such a PIA time getting air out till I changed the line between the frame and the tank last fall? Went over the line nuts tonight just for giggles - I needed a laugh after this bout with air



As far as the rotors and bearing assys I put on I knew it wouldn't be related to the pedal issue - I was hoping to cure a front end issue - seems better ??? Man I'm too pooped to tell.



Thanks for the reply.