Spongy brakes

[grumpyfellow]

I am trying to get a good pedal on my brakes. New callipers, lines etc
New master cylinder but I still can’t get a good pedal. Any comments appreciated

 

[gdh]

Might still have some air in the lines.

 

[XFIRE82]

I agree with gdh , still got air in the lines. They are a bugger to bleed. A power bleeder is best if you have access to one. When I did mine I did it the gravity way. Car up in the air about a foot off the ground. Hooked a clear plastic line from the bleeder screw to a clear glass bottle ( empty Vodka bottle will do ) , then just open all the bleeder screws all 4 wheels and keep the master cyl full and when you stop seeing bubbles in the lines then close off the screw. Can take a long time as it is abit of a slow process. This C3 is a hard one to bleed .

 

[Jeremiad]

Yes, exactly this. Don't forget the bottle. It might take a while. Be steady on that pedal, too. No pumping away, just steady pressure, and don't let that master empty out or you are back to square one.

 

[grumpyfellow]

Thanks for the info. I have bleed them several times and still don’t have much of a pedal. Good to know about pumping because when I did this I got a bit of a pedal but goes away which makes me believe air still in the system. I will keep at it.

 

[Jr. Corvette]

Thanks for the info. I have bleed them several times and still don’t have much of a pedal. Good to know about pumping because when I did this I got a bit of a pedal but goes away which makes me believe air still in the system. I will keep at it.

I had the exact same issue as you. I had installed new master cylinder, new lines, and ‘new’ AC delco calipers. At first I had a few leaks around the fittings but eventually got it bleed but a few days later my brakes would be spongy. Turns out my calipers were leaking. After 3 sets of calipers I finally gave up and went with Wilwoods and haven’t had a problem since.

One thing I did that made me go from hating bleeding brakes, to finding it rather satisfying was the Russle quick bleed screws. Just give it a turn, pump until no more air comes out, then close it up. No pumping...opening...Pressing...Closing...repeat, and you can bleed them on your own so you don’t have to waste a few hours of your friends time if you want to bleed the brakes. So if you are sure that your calipers and lines are fine, I would recommend picking those up if you’re still having issues. It’ll make it faster and less of a hassle.

 

[XFIRE82]

Interesting about the Russle bleed screws , never heard of such a thing , must be a check valve that opens under pressure then closes so not to let air back in when you release the pedal , sounds like a smart idea one man operation and alot quicker than the gravity bleed I was doing.

 

[rick coldin]

I made a pressure bleeder out of a garden sprayer the kind you pump up get an old master cylinder lid and drill and tap it for a line to the garden sprayer open the bleeder screws and don't let the master empty and suck more air in … worked on my pick up too make sure your bleeder screws on the calipers are on top so the air naturally rises out works everytime

 

[XFIRE82]

been thinking about the Russle bleeders , they sound OK, but I have had where even after pumping and open/close the valve , and especially on a long distance to the rear wheels , an air bubble can still be caught in the line as the pedal can only push so far thus the bubble does not travel far enough to escape and when you release the pedal the bubble kinda gets sucked back in . A pressure bleeder forces it all out as there is volume being pushed but can get messy at the master cyl. The gravity way works too but takes time. Another way is the vacume gun that you put the hose on the bleed valve and hand pump the gun which sucks the fluid into a container and when you see no more bubbles then just close the bleeder, care must be taken to keep the master cyl full as to not suck it dry before you close the valve. These vac gun bleeders can be picked up at places like Princess Auto , I have one and it does work.

 

[grumpyfellow]

Thanks for the info.
Turns out one of the rear calipers was leaking at the fitting and would not seal.
I am getting a new one and will give these ideas a whirl.