need brake advice

[vardenafil]

I have a 72 k20 truck. The brake pedal when I bought the truck would never return to normal height after you depress the pedal. I was told it was do to leaky rear drums. I have since replaced the rear drums with a disc conversion kit. the rear is all new hard and braided brake lines. the front i replaced the rubber lines with steel lines. I used a pneumatic bleeder to bleed the truck at all 4 corners. The pedal still wont return to normal height after depressing the pedal. The pedal feels real soft. There is vacuum going to the brake booster although it does hiss a little bit when you depress the pedal. Ive bled the truck like 3 times now. the last time the pedal felt worse after i was done. does this sound like air still trapped in the lines? or master cylinder? or brake booster?

[Steeveedee]

Two things.

1. Did you adjust the calipers on the rear brakes to take up the empty space? They don't just let fluid in to replace that lost from pad friction material wear, like the fronts do.

2. Did you check the brake lever arm to make sure it pulls the lever arm all the way back?

[vardenafil]

I havent adjusted the rear brakes. the calipers barely went on as is due to the pad thickness. I did watch a video on how to adjust the rear brakes by pulling the lever aND letting it slam back in place. but there is little movement in the arm with the rear pads on.

I think the issue might lay in the front or the master or booster. I bled the rear brakes first and the pedal felt firm but would not come up to full height. i went and bled the front and the pedal is non existent now.

[LockDoc]

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A couple of threads:

https://67-72chevytrucks.com/vboard/...d.php?t=834172

https://www.67-72chevytrucks.com/vbo...d.php?t=526792

http://67-72chevytrucks.com/vboard/s...d.php?t=207118

LockDoc

[72SB]

given you hear hissing from booster....either the check valve the vacuum hose attaches to is broken or the booster is bad