no back brakes UNTIL brake pedal on the floor

[onebad4D]

drum brakes not engaging until brake pedal on the floor

1. parking brake works
2. brake shoes are adjusted until slight drag on drums
3. brake hoses are not bulging under pressure
4. front disc brakes work properly (with engine off )

Has anyone EXPERIENCED this problem?

[Oldblueaccord]

drum brakes not engaging until brake pedal on the floor

1. parking brake works
2. brake shoes are adjusted until slight drag on drums
3. brake hoses are not bulging under pressure
4. front disc brakes work properly (with engine off )

Has anyone EXPERIENCED this problem?

Sounds like the master cylinder has failed,assuming it is full and you have no other leaks in the system any place.

For a quick check how well does your Emergancy brake work? Can you get it ot hold the car back with 2-4 clicks on the handle?

Does pulling the e brake up 4 clicks help the pedal feel? This will tell you if the brake shoes to drum are adjusted correctly.

[onebad4D]

If the master cylinder is bad, why do both front brakes work fine?

Pedal feels fine with the engine off. If I adjust the shoes outwards any further, I won't be able to install the drum.

It wouldn't be a quick check for me to check if the parking brake will hold the car...the car is on my QuickJack portable car lift, and it's a real pain to move.

I forgot to mention there's no air in the lines...I bled them with a top-of-the-line Pressure Bleeder system.

[InAccordance]

pull the drums and see if the wheel cylinders are blown.

[onebad4D]

the drum brake cylinders look fine,,,and work fine so long as the pedal is at the bottom of its stroke.

[Oldblueaccord]

[QUOTE=onebad4D;1214922]If the master cylinder is bad, why do both front brakes work fine?

Pedal feels fine with the engine off. If I adjust the shoes outwards any further, I won't be able to install the drum.

It wouldn't be a quick check for me to check if the parking brake will hold the car...the car is on my QuickJack portable car lift, and it's a real pain to move.

I forgot to mention there's no air in the lines...I bled them with a top-of-the-line Pressure Bleeder system.[/QUOTE

master cylinders can go bad on one channel. If the pedal was dropping alot and someone plowed it its easy to push the plunger too far and damage the internals seals. Old metal MC in old school cars you could stand on the pedal with two feet "and hit the floor" and be fine plastic not so much.

If you pull the E brake it moves the shoes towards the drums and lessens the pedal travel. its just a quick check to see if the shoes really are adjusted "up" to the drum. I have had 10 people come to my house over the years and say my drums are adjusted where as they were not and they had alot of pedal drop. Quick pull of the e brake will tell you where your at. you dont need to move the car or be on the ground.

[onebad4D]

I think you're right about the master cylinder being bad. It was very difficult to separate from the booster...I had to pry it off with great force. It had goo all over the flange and boss.

Pulling the parking brake didn't change the pedal travel.

One of the drum brake shoes is worn unevenly...it varies in thickness from about 1mm to 3mm. The other shoe looks great. I guess I'll replace them as a set after I fix whatever is causing the uneven wear.