Brake problem

[mpg9999]

My brake pedal never seems to be firm enough. It sometimes gets better right after I bleed it but it gets softer again later. Usually I see very little to no air come out of the front calipers. The rears however I get what seems like an unending supply of air. The fluid that comes out also appears to have some rust or rust like particles floating around in it. One theory is maybe the piston bores are rusted out, and this is causing both the air issue and the rusty brake fluid issue.

Another thing that I've noticed is that I can bottom out the brake pedal with enough force (I don't have to stand on it, but its not a little bit of force either). I'm not sure if that should happen. This leads me to believe that I could have some sort of MC problem.

So, what do you guys think? Replace the rear calipers and MC?

[Andy]

If you can bottom out the pedal then you have a bad MC.

[Evan]

"unending bubbles" in the rear just sounds like air is getting sucked through the threads on the bleeder. tape the bleeder with teflon tape and see if it stops

[Andy]

If air is getting sucked in at the bleeder valve, wouldn't fluid also be coming out when he's on his brakes. He would have seen that, correct?

[Evan]

no, because the bleeder is open when you bleed

[Andy]

I've never backed out my bleeder that much. Never heard of that problem.

[.RJ]

I've never backed out my bleeder that much

You dont have to back out the bleeder that much for it to happen.

[Dave]

I couldn't remember, do you have the NX2000 brake upgrade? If so, you'll always have a bit more play in the pedal than stock, until you get a MC with a bigger bore.
Sounds to me like you could use a MC rebuild or a newer MC anyways. If you get a new one, go ahead and get one for an NX2000, in case you ever do that mod (definitely worth the $$$).