After installing Rear Discs and an Integra Prop Valve my braking will usually be very good. But every once in a while I will press down the brake pedal and it will keep slowly going all the way to the floor when usually it gets very firm half way down. So why does it do this? I am sure the brakes are bled right since most of the time the pedal is firm. I don't think there are any leaks. What could be wrong?

 

I think you might have air in the brake lines

 

Then how come it doesn't do it all the time?

 

You might want to check your brake booster for proper connection to vacuum source and to make sure that it is not leaking. Also check your master cylinder to make sure that it is good. I have heard that sometimes the seal on the pushrod into the master cylinder can go bad, causing all sorts of havoc with leaking fluid.

 

Something also to consider is what type of brake fluid are you using?

Cheap **** brake fluid has a tendancy to collect moisture and turn acidic, eating away at your MC. The signs are like you describe. Not bad at first, but over time it'll become worse.

I could be way off, but just a thought.

 

I had a very similar problem. I replaced my MC and it solved it. It began like you said at first, then after a few months it would go down all the time. I would have to pump the brakes initially in order to brake. Like I said though, once I replaced the MC it went away.
One thing you might want to do is bleed the MC. Maybe there is some air traped in their. Once you do that, you will have bleed the brakes again.

 

Change brake fluid once a year at a minimum, that will keep most problems down. Brake fluid does go bad. My guess is the master cylinder is starting to go bad.


[Modified by SirYoda, 5:25 PM 10/3/2002]

 

 

I have Castrol GTLMA DOT 4.0 fluid, so its not shitty fluid. And this problem just started after my rear disc swap never before, so I doubt it would be such a coincidence. I think I may have air in the lines.

When I bleed the fronts with a Mity-Vac I can pump it so it will eventually suck out by itself and when I pull off the hose it makes a sound like a soda can opening. The back doesn't do this. So do I need to keep doing that until it goes pop when I pull off the line?

 

Easy way to find out if its the mc is to plug it....if it stays firm(the pedal) your mc is fine....otherwise...if there are no external leaks....you have an internal leak in your mc...and you need to replace it.....

If your booster is bad....turn the car off...pump the brakes...when you turn the car on....if the pedal goes down slightly your booster is working correctly if you pump it up.turn the car on...if the pedal stays hard....your booster is bad...

My guess is you have air in your system...or you flat out didnt bleed your brakes properly in the correct sequence as well....

remember bleeding pattern on crx's go 2-4
3-1

 

heres a better view of the sequence...

2---4

3---1

start pass. rear....and go across to drivers side front....then driver side rear....then pass. front....

 

I did Rear Passeneger, Front Driver, Rear Driver, then Front Passenger. Which I believe is correct. I am damn sure the fronts are fine. So if the fronts were fine and I went back and just bled the rears would I have to bleed the fronts. Because I know if you only expose air to one wheel you only have to bleed that wheel. So knowing the rears have the air can I just bleed them?

 

Also some people tell me that I won't be able to get the air out myself and taking it to a shop is better. Should I just do that. What would it run just to bleed it?

 

definite master cylinder, if it was air in the lines it would happen all the time

 

I had the exact thing happen to my rex. It continually got worse. I picked up a rebuilt master cylinder, installed and bled the brakes. No problems since.

Good luck

 

I found out the problem. The vaccum hose that goes to the booster is old and nasty so as a temp fix I wrapped it in duct tape and ordered new hoses which will come soon. Have had no problems since.