brake troubles... not a reaction disk issue.

[clsatt]

I have soggy brakes. when I bought the car I assumed it was a reaction disk issue, checked that it was fine. so I plugged everything back in and tried them again. sounded like I had a vaccume leak, I replaced the vaccume line and valve. still sounded leaky so I bought a new booster.

 

I still have soggy brakes. I have tried the valve both ways, it changes the feel of the pedal but doesn't do a damn thing for the actuall stopping power of the car. it almost feels like I have manual brakes.

 

what I know is that there isn't a leak in the lines. I know that the front pads are new, and the guy I bought the car from told me he rebuilt the cylinder shortly before he had to sell it. I must have bled the lines 8 times.

 

when I push the pedal there is no resistance through the first 2/3 of the stroke, then it feels like brakes should but it never really builds up a good deal of pressure. if I stop standing on them (litterally standing on them) on a hill I'll start to roll backwards. also if I pump them about three or four times it feels like I have good pressure but with a fifth push I feel a pop at the botem of the stroke, like I just blew all that pressure by a seal.

 

thats all I can think of. if anyone can diagnose this I would be greatfull.

 

 

thanks,

chris

[clsatt]

I forgot to mention what the car was... 1970 240z, stock brake system.

[Pop N Wood]

You need to lengthen the rod going from the brake pedal into the back of the booster (the one that contacts the reaction disk). Make it longer so that the brakes start to catch after a half inch or so of pedal travel.

 

I have no idea with an otherwise stock system why that rod would suddenly be too short. But if a "previous owner" is involved than anything is possible.

 

Triple check that reaction disk in the process.

[GrommitZ]

It sounds like you have more than one problem. Did you bleed directly from the master cylinder? You have to open the mc bleeder valves fast and far enough to get the air out of the top of the cylinder, but not bottom the brake pedal while doing so.

 

It also sounds like your brake booster is improperly adjusted if the rod that attaches to the brake pedal doesn't release far enough, the booster won't seal the vacuum. Without the assist, your brakes will feel like manual ones. Also check the rod that Pop N Wood suggested.

 

If your reaction disk didn't fall out earlier, it might have by now because of the long pedal stroke and the pop you heard. This should not account for the weak braking power.

[clsatt]

I havn't bled the master, honestly because I didn't know how. I'll try that today. and I'll adjust that rod while I'm at it. unless the long throw could have caused the reaction disk to fall out, it'll still be there, after reading all the horror stories on here about them, I made sure that it was in place propperly when I installed the new booster. these suggestions are great, if you come up with anything else let me know. I'll tell you how these ones work out.

 

thanks,

chris

[2003z]

also check to see that the brakes are on the correct side of the car. It sounds simple, but is a fairly common problem when removing and reinstalling calipers. The bleed screw should be above the fluid line going into the caliper. If the calipers are on the wrong side, it will be below the fluid line and impossible to bleed the calipers completely.

[clsatt]

well, my brakes fixed. I replaced the MC and everything s as it should be. I also adjusted that rod while I was at it.

 

thanks guys,

chris