saburai
Full Access Member
Will a faulty or leaking vacuum booster cause a sinking pedal?
Bad brake booster?
- Thread starter saburai
- Start date
79jasper
Chickenhawk
Sinking pedal is usually rears out of adjustment.
Sent from my SM-N960U using Tapatalk
Sent from my SM-N960U using Tapatalk
saburai
Full Access Member
Just had the rears apart to check. Shoes are almost brand new, .06 thinner than new NAPA fleet shoes. Adjustment is fine. Gotta be the master, right?
79jasper
Chickenhawk
Pretty much.
If you pump them a bit and still bleeds down, I would say master.
Have you bled it all pretty good?
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If you pump them a bit and still bleeds down, I would say master.
Have you bled it all pretty good?
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saburai
Full Access Member
Yes, I flushed nearly a gallon through the system until it ran clear. The master and reservoir look comparatively new so I didn't suspect it. I did eliminate the RABS valve since that's what I had first thought was the cause of the sinking pedal. I've gone through the whole system, the master is the only thing that's left...
Randy Bush
Full Access Member
Although have not done it yet on mine, I think the real way to test the MC is to find fittings to plug off the mc and see if it is bypassing or not. Have done a lot on mine and still have the problem.
saburai
Full Access Member
Did you eliminate the RABS?
Randy Bush
Full Access Member
Nope , put a good one off a dead truck I have, same problem.
saburai
Full Access Member
So if I understand, you replaced the MC, know that the RABS valve is good and have no leaks. In my mind, if you are sure about the RABS valve, you've got a bad master...
