The clue is in your last sentence. "Pumping helps" is the main symptom of misadjusted drum brakes. The shoes have to move a long way to contact the drum before pressure can build up, and that results in a low brake pedal. It takes a substantial amount of time for the shoes to slowly retract, so when you immediately push the brake pedal again, you get more brake fluid into the system, so that next pump pushes the shoes out further. By the third or fourth pump, the shoes hit the drums and pressure starts to build up.
There's a real lot more involved in a professional brake job than just hanging new shoes or pads. There are a number of things we do to avoid causing noises and vibrations. Proper shoe adjustment is one of the things that's part of that job. We also use special high-temperature grease in critical places. Failure to do that won't cause a problem today, but it will prevent wear that can cause elusive symptoms later.
Did you have the drums machined? If not, there's a ridge of rust on the outer edge and the inner part near the mounting hub. That will make the drum hard to install if the shoes are adjusted properly and it can cause a low brake pedal by falsely making the shoes appear to be in adjustment. Drums also need to be measured to see if they're within the manufacturer's published legal diameter. If they are too large, the shoes may be unable to adjust far enough to get a good pedal.
There's a bar between the two shoes with a toothed wheel, and a spring-loaded lever that turns that wheel. You need to spin that wheel to expand the shoes, then the lever will take over as the linings wear down. If that bar is loose or the adjustment is too little, the lever won't work.
Monday, November 9th, 2015 AT 5:03 PM
