2006 1500 rclb disc/drum, very low brake pedal.

[kenman1717]

Its an '06 1500 w/ 4.8l, was towed in because left rear wheel was smoking, and no brake pedal. Managed to get the left rear drum off and the brakes were toast. No shoe left, wheel cylinder mangled, horse shoe hold down was very soft and bent easy, adjust seized way out. Right rear brakes perfect, and everything worked fine, front brake calipers in good shape. Replaced everything on the left rear, and cleaned out the left rear brake line, as it was plugged between the junction and the wheel cylinder. Put new shoes and drum on right rear, adjusted the rear brakes up as much as a dared. Bleed all 4 wheels in the correct pattern numerous times to flush the old fluid out. Did the automated bleed about 3 times, which helped a little. but on the road test the pedal is still on the floor. Was able to adjust the rear drums a bit more after the road test, rebled, did another automated bleed, but no luck. I'm almost thinking it might be the master cylinder. Pretty sure the booster is good, the brake pedal is solid with the key off. thanks. any help is appreciated.

[maxwedge]

You had a scanner to properly bleed the abs?

[kenman1717]

Originally Posted by maxwedge

You had a scanner to properly bleed the abs?

yes, I did it like 4 times.

[kenman1717]

My boss wanted me to get this figured out, so I pulled the master cylinder off the booster, and found the bore that the master fits into had lots of brake fluid in it as well as some splashed around inside the booster. I decided to order a master cylinder, couldn't get a GM one, only 2 in Canada on the east coast, back ordered in North America. Only one 'new' Napa one available, no booster available locally so, I took a chance with just the master. Bench bled it and installed it. Of course the plug in the level sensor was to small for the connector, so I swapped in the old one. Bled all the brakes again, and used my Snap On scanner to do the abs bleed, and yes its the same procedure as GM uses. The pedal is a lot higher and feels a lot firmer. Not exactly the pedal feel I would want if it was my truck, but I have 4 wheel disc in mine. But its another bush truck with 350 000kms on it so it will serve their purpose. Honestly though the company that owns it has already spent like 8 grand on this truck in the last 3 months, its not worth it, but they want it to finish the summer, so they say.

[kenman1717]

There must be something really common with this year/model and brake set up, I just did another one, same company actually. Left wheel brakes smoked, everything exactly the same. Only difference I was able to do this one without replacing the master cylinder. It just seems odd to me that the exact same thing happened to another truck, but yet its the same setup. Has anyone else ever experience this on a disc/drum setup of around the same year? This is just bizarre.