Brake locks up

[napz510]

Hi everybody..I'm new to this forum.Hope you guys can figure it out what's wrong to my brakes that locks up.

I have a 510 4 doors with new rebuilt calipers on front (280zx) and Maxima caliper at the rear.I replaced the brake master with the 280zx master.I bench bled it,i got half inch of play on the push rod and bled all the calipers.Was working ok then after it gets hot, it locks up.I have to bled one of the calipers or any bleeder that i can bled then I'm gonna be ok for a while.

I'm running out of ideas and been reading all this forums to any site and did everything and still locks up.

Thanks guys...

[datzenmike]

Usually it the pedal free play. Remove the clip and pin connecting the pedal to the push rod and make sure it's free to move back to it's rest position.

[napz510]

Thanks for the quick response.....yes I did that...when you step the pedal it has like an inch play before it pushes the rod. If the brakes locks up and i'll let stay to cool down.It releases the brake a little bit and i can still feel that pedal is hard or stiff.I have to bleed it just release completely.

Is that because i have a 15/16 master?I'm asking that because I read it from one the threads that 15/16 is more stiffer/ harder.Do you think that's one of the problem?

 

thanks

[jesusno2]

I had this issue with motorcyle calipers alot my problem was from paint build up and the calipers not releasing or they had junk in the piston bores not letting them release.I'd almost put money on it that your problem lies in the calipers somewhere. I know a few dudes running the 15 16 master with no problems in fact that's what I'm gonna put on my goon when the time comes

[datzenmike]

When you take your foot off the brake pedal, the piston in the m/c is pushed back by the pressure in the lines, and will (or should) vent fluid back into the master reservoir. A stuck caliper piston will not cause pressure in the lines.

 

Are you using a brake booster?

[banzai510(hainz)]

My Jeep did this.

I bought new calipers. Cheap 20$ apc!!!!

 

Never had a proplem w/my 510 calipers.

[napz510]

I don't have brake booster...All the brakes locks up not only one.The pedal have play but when it pushes the rod , it's hard until i have to bleed one of the bleeder.I'll try to rebleed it again.Sorry guys....just running out of ideas.

Thanks for all the response.

[datzenmike]

Did you re-build the master cylinder, or have it apart?

[napz510]

I bought it rebuilt from kragen autoparts.

[datzenmike]

So, being a dual brake system, how can any pressure remain in both systems if it is normally allowed to return to the reservoir by the master cylinder when at rest position. (note) the only exception, is the residual check valves in both systems that retain several pounds pressure in the lines so that air cannot enter past caliper seals.

 

From your description of all calipers locking and excess pressure remaining in both front and back systems, it sounds to me like it's the master cylinder.

Edited November 12, 2008 by datzenmike

[napz510]

Ok, I'll try to replace that and let you guys know.Thanks....

[napz510]

I rebled the master and still the same thing.So i replaced it with the 3/4 master that my buddy gave it to me. Bled it and test drove it.works great....thanks guys!

[72nismo]

Your welcome!!!!!:D:d

[ppeters914]

Nice. Datzenmike gets a sea-gar, and you get brakes.

 

Did you take the reman 15/16 back to Kragen and get your money back? :D

[Llittle_Llama]

sounds like the problem i had with my 240, here is a link.... http://forums.nicoclub.com/zerothread?id=372473&postid=4110325

[datsunfish]

My 620 has been sticky lately. Then yesterday the front locked up so bad that it wouldnt even move. I had to crack the front bleeder on the MC and I was rolling again. Had to keep it open and limp home with only the rear. Definitely the MC not retracting. I had a clutch master do the same thing before too. Sucks you said it was new but maybe they will warranty it.