blazerdup

I have a spongy/soft brake pedal unless I pump it once or twice. I have tried many things but nothing is fixing it. So should I take the MC off the car and bench bleed it again? I had some trouble getting it to not have an little air bubble in it when I first got it. So is it possible I didn'tdo a good enough job?

Looking for some other opinions.

Thanks

kalli

sounds like air in there. if bleeding doesn't help, then yes bench bleeding is the next thing. of course make sure there are no leaks anywhere in the system. if you loose fluid anywhere it will be replaced with air

KMatch

Once you get much of a pedal at all, there's not much more bench bleeding will do. One option to remove the air that gets trapped between the bench and mounting it on the car is: prepare for spilled fluid under as well as all around the master cylinder with a rag. Have someone pump up the brakes and hold pressure. Break the lines loose at the master cylinder (expect fluid to go any direction, it's under pressure) then retighten. Repeat a few times. The pressure in the lines removes any air that was in the top of the brake lines as well as the master cylinder. It does the same as bench bleeding, but does it better as no air will be allowed as is always the case when going from bench to car.

Still got a spongy pedal? It's time to bleed at the wheels.

blazerdup

ok I will give that a try. Thanks,

zmetalmilitia

So you did bench bleed once already? Sounds like you did, I would just bleed the brakes at the wheels, of course starting at the furthest wheel away from the mc moving to the next furthest and so on. Like said, if there are any leaks, the ever so slightest loose connection, air will be the little sucker casing your troubles. Recheck your connections, making sure there is no dirt or rust, grime, whatever in the threads and the bleed at the wheels.

Have you replaced the brake fluid recently?

blazerdup

I have bled the brakes about 4 times already. I put brand new lines and new MC and new fluid of course. I will go over the lines again. One thing I did notice when bleeding the last time was how the front brake lines kept having a puff of air bubbles every couple of pumps. So it seems to be only the front lines; the rear lines were solid and no air. I am going to re-check the whole thing today, replace the front wheel cylinders and re-bleed at the wheels and see how it is. Wish me luck.

zmetalmilitia

Yeah, if you saw air in the front brakes, that is the source of the problem. Focus on that area. Good luck. At least you have warm weather to do this.

kalli

start at the furthest away wheel from MC and work your way closer to it
So start with rear passenger side, then rear driver side, then front passenger and finally front driver
don't stop until all bubbles are out.

guitarman376

If nothing else helps, read my recent post titled "Strange Brake Happenings" . Basically your master cylinder might not have residual pressure valves built in. Read the thread for more info

chockostang

Right.

The Front Port of the master (Which is the rear brake circuit) should have a 10 pound residual for a rear drum system.

If not, install a 10 pound residual in the rear brake line.

Next, is adjustment, adjustment, Yes adjustment. Most folks rebuilding the rear drum brakes fail to adjust the shoes out far enough to center the shoes. If you adjust untell you heard a small scraping sound, the shoes did not center, the wheel cylinders are trying to reach the drum surface (That's the pumping, or soft pedal)

Adjustment has to be full lock on the wheel, then back off to a small amount of contact between shoe, and drum is noted.

Dan @ Chockostang