View Full Version : Z32 rear brakes locking up problems
Tenchuu
03-29-2009, 05:27 PM
looking for some help here, didn't find anyhting pertaining in searching.
Parts used:
Z32 30mm aluminum fronts
Z32 matching rears
Z32 ABS brake booster
17/16 BMC
97 240sx auto brake booster check valve
so i put front brakes on first without check vales in the booster, worked fine. finally got the rotors and put on the rears without check valve, worked fine.
during this time the brakes behaved strangely, the came to a hard stop , but once stopped the petal would sink to the floor. found out that i drunkenly didn't screw in a brake line quite tight enough and thought this was the problem.
no dice, it is doing it less, but still doing it. so naturally i figured there is now some air in the lines in the front (rears are on and freshly bled) now i put in the check valve to get it back working like it is supposed to, and i can only drive about 6-10 block before the rear brakes slowly seize up on me, i release the check valve, and the work fine.
am i correct in assuming that somehow the Z32 ABS BMC is holding too much pressure and that is causing the rears to slowly lock over prolonged braking?
note this is not at highway speeds where i never get to the "sinking past full stop" on the brake pedal it worked fine, i drove it for two hours. now in stop and go and can't get across town.
would appreciate some help. i removed the check valve and it works OK again except for the huge vacuum leak it opens that causes bad idle.
cut to chase: Z32 ABS BMC should not be used in S chasis. not only does it fit horrible, is also a PITA to adjust and get to work properly.
Tenchuu
03-29-2009, 08:30 PM
tried adjusting the nut on the booster. time will tell if it does anything.
seems to have worked, but i belive it is adjsuted too much as the pedal is mush and the fronts get wayyy to much of the stopping force now.
slider2828
03-30-2009, 12:17 AM
Did you adjust it with a vice grip? It DOES work.... That nut... You have to hold the stem with needle nose vice grips to hold the stem and then turn the nut/cap. Its a 7mm. I just did this.... If you just turn the cap it doesn't do anything cause it doesn't go in....
The best is turn the cap in till on 1.5 threads are visible, so its almost all the way... Hope this helps.
when u say "lock up after a while" i say moisture in the lines or your rear parking adjustment is too much... and when u say "I did not screw it on right" (thats what she said )lol j/k "and i tightend it back and kinda fixed it" air got in through there and u need to bleed it again.. and as for your pedal.... u know what (move) the m/c and adjust the rod out a little at a time adjust and test... bleed m/c bleed all brakes then adjust. AND MAKE SURE THE BLEEDERS R ON THE TOP SIDE of the calipers NOT THE BOTTOM.. cuz they will not bleed correctly..... good luck ...
Tenchuu
10-08-2009, 01:51 PM
so back on this subject, i thought it worked, but after running about 16 laps at an auto X i noticed that it was dragging again, so now comes more adjustment on the nut.
also i have super blue fluid in there(read does not absorb water), that has been flushed many time so i think that water is out of the question. the bleeders are on the top, that is a major fubar if you don't do that right the first time.
also to note is that adjusting the puck firmed up the brake pedal. it is now normal and gives feedback.
slider2828
10-09-2009, 10:38 AM
Super Blue is overrated, just get motul if you can RBF600 or better. Now you sure its not the rear thats dragging via hand bracks.
You mean your bleeder screws were on the bottom before? Also what puck are you referring... just so I know hahah . Thanks!
there could be something wrong with the parking brake, like the hardware is weak and can cause the shoes to drag and eventually lock up on u, do u have new hardware? is the parking brake adjusted correctly?
Tenchuu
10-10-2009, 12:41 AM
the parking brake is wayyyyy loose (R33 cable, doesn't engage fully until the last 1/2 inch of parking brake pull) i will keep this thread informed if this did the trick. so far so good.
the reason i go super blue is that it is $12 a liter locally. motul is more than that for 1/2 as much and i have to pay shipping, so 3x more expensive said and done. seems a bit overkill for a DD/ auto X car that isn't competitive.
and i am kind of insulted that everyone keeps on asking if the bleeder valves are on the bottom. you have no right to do anything to your car if you make that rookie of a mistake. i may be no pro at the brake system, but even i know that much.
and i am kind of insulted that everyone keeps on asking if the bleeder valves are on the bottom. you have no right to do anything to your car if you make that rookie of a mistake. i may be no pro at the brake system, but even i know that much.
lol were just checkin... we are diagnosin a car over the net u know ^^
im going to check my books and see if I can find more stuff to check for...
projectRDM
10-10-2009, 11:22 AM
and i am kind of insulted that everyone keeps on asking if the bleeder valves are on the bottom. you have no right to do anything to your car if you make that rookie of a mistake. i may be no pro at the brake system, but even i know that much.
You do realize this is Zilvia. And 240SX owners. There aren't very many people on here that aren't completely stupid as fuck. Don't get offended if someone assumes you are too, it's a common mistake.
based on what ive read u either have corrosion or rust buildup somewhere in the system since 30mm are iron or your harware sucks and needs to be reconditioned OR its installed incorreclty *huff* OR lol its adjusted wrong........ heres and idea remove all your parking brake parts then drive it and see what happens.... if its till happens check ur lines and ajust ur m/c and dont alter the brake system by removing check valves there there for a reason... and make sure ur parts are in good condition....
slider2828
10-12-2009, 11:13 AM
Wow don't be so worked up, when I installed mine, it was always up (bleeder screw that is...) why get so mad.... its only a forum and internet... I asked bleeder screw down just to see if it was making a big difference.... I get motul locally at $16.... I thought it was a normal thing to get it locally... My buddy ran blue in his civic (race prepped) and didn't like it so much.... but hey whatever
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