Diagnosing Soft Brake Pedal

[HondaBoy]

ok, today i decided to bleed out the brakes on my 3gee. everything went nice until i went to test the brake pedal. it was pretty nice before i bled the lines out. so i went around and bled the lines again, same thing, soft pedal. so i just bled out the rear brakes and that pretty much fixed the problem. mainly the left rear helped. i was first thinking my master cylinder was going out, but the rear cylinders leaked some. enought to leave gunk inside the drums. does that sound right? the wheel cylinders would cause this problem? it was only after bleeding the front brakes, as if the rear cylinders were then sucking in air. mind you that i used a brake bleeder that uses vacuum to draw out the fluid. the rear cylinders are $18.99 each with lifetime warrenty. anyway, just wondering if anyone else with brake experience would have an opinion on this.

[lostforawhile]

I just went through this myself, the left side shoe had worn completly out and the right one had been untouched after rebuilding them a year or two ago. and both my new brake cyls. are leaking again. they are good quality ones from nappa too. what had caused the problem on the shoe was the right side adjuster was not working and the left side one was doing all the work. when you rebuild your brakes if the adjusters aren't working the brakes won't contact the drums properly and the rear brakes won't be effective. the rear wheel cyls will also all the way extended and make your brake pedal feel mushy due to more fluid going to the rear. did you adjust your brakes after putting the drums back on? my pedal was going almost to the floor until I manually adjusted the rears after replacing the adjusters, all new hardware and new shoes. that was after bleeding them. if you have newer cyls they are very easy to rebuild. just a couple of dust caps and some cyl seals. if there is any corrosion you can buy a small brake hone for them. if after honing there is still corrosion you need new cylnds. and yes bad wheel cylnders can cause air to get into the line.

[HondaBoy]

actually friday i adjusted the rear brakes, but didnt today. i didnt think it would be neccesary, considering the rear brakes are still draggin just a bit. also, i have seen the cylinders leakage mixed with brake dust all on the backing plate. i'm going to see how the brakes chage, if at all, between today and tomorrow.

[2oodoor]

im not sure what all you have done there, but there is a cliche that fits well , 'if it aint broke, dont fix it' lol
on that type system I like to gravity bleed, just open the top of master cyl. and make sure its full, then open up slightley the longest brake line, probably LR, and let is drip untill it is steady stream, it is not opened up much , just barely enough for some drip to come out.. then close off and do RR the same., making sure the mas cyl stays full. That technique works best for me when im by myself bleeding rears. Its tricky so the front can retain air doing the same way if you dont keep them pumped up , so I will leave this post as just how I DO it and not telling you how you should do it ok. If you have funk inside your drum , yess you have leaking wheel cyl, before you ever started. If the pedal was soft before you ever started touching it, you could have front caliper sticking or colapsed flex line going to caliper. some cars that would cause hard pedal but it depends on how heavy the car is.hope any of that helps, I have not read many threads on brakes here, Im just going by what I have seen on other cars. dont muck around with brakes , get them right, check everything,.best luck to ya

[Jasonf860]

I've been having a similar problem. When I first start driving, the first few stops I practically have to stand on the pedal to stop. After 2-3 like this, it goes away and I barely have to touch it to stop. A friend of mine said that my brakes may work a lot better when they are warm, but they are just standard pads from Autozone... Sorry to jack your thread, but anyone have thoughts on the matter?

[2oodoor]

Lost musta been writing the same time as me, his advice is excellant too if that is the direction you were going, didnt know if you had pulled drums or not. the description SOFT PEDAL can be taken several ways, so as a technician , questions have to be asked ya know,

[2oodoor]

yeah Jason... your problem sounds more like brake booster vacuum problem. clean out your vacuum line and ports to make sure your geting strong vacuum to booster., you may have a thermovalve leaking when cold and making a vacuum leak, thus not powering the booster.

[lostforawhile]

I've been having a similar problem. When I first start driving, the first few stops I practically have to stand on the pedal to stop. After 2-3 like this, it goes away and I barely have to touch it to stop. A friend of mine said that my brakes may work a lot better when they are warm, but they are just standard pads from Autozone... Sorry to jack your thread, but anyone have thoughts on the matter?when you reset the calipers to change the brake pads or shoes,you have to pump the brake a few times first. the fluid has been pushed backwards through the master cyl. and this resets everything. also when you do rear shoes,when they are all the way reset sometimes the adjuster won't catch that far in,so you have to manually adjust at first. if the adjuster is working,everytime you push the brake pedal,that toothed rachet will move the shoes farther apart until they are reset.

[HondaBoy]

also, i now remember that when servicing my brakes a few months back, the rear brakes seemed to have a lot of air and dirty fluid in them compared to the fronts. maybe i just need to replace the cylinder? i was still wondering about the master cylinder, but by the way the system responded to bleeding the rears last, i feel they are the cause. i will look more into whats going on tomorrow.

[Jasonf860]

Thanks for the info guys, I'll check into the rears not being adjusted and also look for any vacuum leaks tonight while I'm out doing other misc. stuff to the car.:chainsaw:

[HondaBoy]

i also had a suggestion from one of my classmates. the canister on the bleeder kit that the fluid is drawn into has to hold vacuum. and i was having trouble keeping vacuum in it without pushing down some onto the gasket. anyways, the brakes seem fine now so i dunno. they proved themselves yesterday, so i think maybe i was just being quite paranoid after they went kinda soft. now they seem to be normal where they should be.