View Full Version : trying to get rear drums to work

07-22-2008, 01:06 PM
Ok, so I am trying to get the rear drum brakes to work, heres what I got: Spirit 27 frame kit with power brakes, gm 10 bolt drum rear end, new wheel cylinders, springs and shoes.

I ran the line coming out of the rear port of the M/C, to a -3an bulkhead fittings on the frame, to a -3an flex line about 13" long to a brass Tee on the rear end. From the tee, the lines go to wheel cylinders.

I am using a vacuum bleeder to suck the air out of the lines (I bleed the M/C before attaching any line). I can get clean fluid out of the passenger side rear drum, but constantly get air and brake fluid out of the driver side rear. I have checked all the lines and fittings and dont see any leaks.

With everything attached, I tried pressing the brake pedal and the drum shoes dont move, at all. I pressed in the wheel cylinder a little bit and pressed on the pedal again and the pistons inside the wheel cylinder moved out until it touched the shoes, but still didn't push the shoe out any.

I tried pulling the flex line off at the tee on the rear end, and it doesn't look like it is full of fluid. I attached pressure gauge to the flex line and was getting about 250 PSI (after bleeding the line a bit)

Any ideas? Is 250 PSI sound a little low to anyone?

08-03-2008, 05:25 PM
Have you adjusted the pistons out so they are just touching the brake pads? You might be getting movement but not enough to press out the pads if the pistons aren't touching.

Just a hint.


08-03-2008, 09:28 PM
After going through every component of the brake system, I figured out the problem, I put pressure gauges on the ports on the master cylinder and figured out I was only getting 200 PSI output when I pressed the brake pedal before the pedal became very hard to press. I checked the pedal ratio and it turned out to be 2.5 to 1. I drilled a new hole on the pedal arm to get a 4 to 1 pedal ratio and checked the pressure output again. The pressure shoot up to 400 easily and 600 with a little force down on the pedal (without the power brakes) Brakes work great now