Fire_Wessle

Hey Guys,

I'm out of ideas on what to try at this point. This all started with a master cylinder replacement and the ac Delco I ordered was defective from factory. My mechanic replaced it with a Doorman from Autozone and I've been chasing this soft brake pedal issue for months now.
Symptoms

1. No usable brake power until pedal is half depressed traveling over 5 mph
2. Brakes do catch slightly when depressed 1-3 inches but this only slows the car down when traveling under 5mph
3. At highway speeds I can pump the pedal twice and it will give me brakes about 3 inches depressed
4. No uneven front pad wear
5. Slide pins are good

Attempted fixes

1. Bled the lines multiple times to make sure there are no air bubbles
2. Attempted to bleed air from the Doorman master cylinder while installed on the car by cracking the fittings, pressing the peddal to the floor, and tightening before releasing the pedal
3. Replaced rear wheel cylinders
4. Had new lines/fittings installed at the rear wheel cylinders and at the master cylinder as they were heavily corroded

I have no idea of I just got unlucky with 2 bad master cylinders in a row, if there is actually air trapped in the system somewhere, or if this is just a limitation of the Doorman part. How far do you guys have to press the pedal before the pads catch?

tiapetra

Hopefully he bench bled the master first before installing.
Were the rears adjusted manually first?
Can your mechanic pressure bleed?

Oldblue

It is possible to simply gravity bleed the brakes, but I suspect the rear shoes aren’t adjusted correctly, and the master wasn’t bench bled.

Fire_Wessle

Rear shoes have been adjusted as the spring kit, drums, shoes were the first thing that were inspected and replaced.

It's definitely possible it wasn't completely bench bled before install. Would I be able to do that with it on the car or is it most likely shot now that I've driven on it like this?

What is gravity bleeding I haven't heard of that before?

Fire_Wessle

I believe the rear was manually adjusted first but im notnsure if my mechanic can pressure bleed.

RJ_RS_SS_350

Maybe it wasn't bled in the correct order. Bleeding order is not what you might think it is.

Oldblue

NEVER Bleed Brakes Until Watching This! Gravity Brake Bleeding - YouTube

Pretty simple

Fire_Wessle

I do not have abs on my hhr, so I'm fairly certain it's RR, LR, RF then LF. Working my way from the longest line to the shortest line.

Fire_Wessle

Definitly going to give this a shot! Seems to be way less hassle than pumping the fluid with the pedal. I'll start with disconnecting the 2 lines from the master cylinder and using a master cylinder bleeding kit to hopefully get any air out. Then I'll gravity bleed the lines and test drive. If that doesn't fix it it's gotta be the shoes/drums

Oldblue

Or a bad brake booster.