Brakes won't work

[gb20]

My pedal goes all the way to the floor with very little resistance, and doesn't begine slowing the car until it gets there. I checked for leaks and couldn't find any (doesn't mean there any there). I changed brake pads, and bled the system with no improvement. After bleeding the brakes, I noticed some kind of "air" noise coming from the front resevoir on the master cylinder, while my friend pumped the brakes. While she pumped the brakes, the fluid level dropped in that resevoir with each pump and she reported a much better feel in the pedal. Once I had her stop, all the fluid that been drawn into the lines came back up into the resevoir. Then of course, the brakes went right back to the floor. I searched for similar problems on here and the 2 I found suggested it may be a faulty master cylinder. So I ordered one from silverminemotors.com. Got here 2 days later and I put it in, hopes high this would fix the issue. No difference at all. I'm stuck as to what it could be. If any of you have a clue, please fill me in. Thanks for your time, its much apprecieated.

[blue72]

A few more little details might help. Which year car is it, and is it the stock brake system, or modified?

Not knowing those things, I'll assume an S30? If it is, I might suggest reading up on the reaction disk, because it can cause the exact same brake pedal feel.

Here's a link to the little writeup I did on it over in the brakes, wheels, suspension and chassis sub forum.

http://forums.hybridz.org/showthread.php?t=138712

[gb20]

Yeah, it's a '74 260 with stock system. Thanks for the info, I'll get to reading.

[gb20]

Well, after reading that post I finally went out to give the reaction disk a look. It's still right there where it should be, looking nice and clean. Are there any other things I should look at? I really don't want to take it to a "professoinal" to have it looked at, so any ideas would be graciously accepted. Thanks.

[240zwannabe]

make sure you didn't put your calipers on upside down if you've had them out. the bleeder valve should be on top.

[Netrix]

To do:

-Check calipers, pads

-Check rear drums and brake cylinder (see if they're leaking, might need a rebuild)

-If they all check out, I'd drain the system completely and rebleed, keep going even though you don't see bubbles.

-Check Master Vac

 

Remember, you can buy rebuild kits for your master cylinder, wheel cylinders, and calipers. Think that's not smart? Well they have people in china rebuilding them making 10 cents an hour, think they care if you die, because they didn't pay attention rebuilding it? Plus it saves you $$$ Black Dragon Auto sells some of the rebuild kits.

[blue72]

I was going to mention the upside down caliper possibility in my first post, but I guess I forgot.

I was listening to CarTalk about a month back, and one of the callers went through his whole process of elimination with Click and Clack. He explained how his brakes didn't work correctly after a simple brake job, but it wasn't until the end when they asked him about his bleeding procedure, then they found the problem. He had done everything else correctly, but had the pump pedal/open bleeder valve sequence a little backward.

 

It might not be what you are experiencing, but I just thought it interesting that sometimes it turns out to be one of the things that have already been ruled out. It just takes a different point of view to see it. Sometimes it is the simple little things you wouldn't otherwise think twice about.