brake going to the floor...sometimes
10-17-2009, 09:04 PM
#1
Drifting
Thread Starter
brake going to the floor...sometimes
i'm not sure what's going on here.
with engine off, i can pump the pedal and get solid firm pressure. but as soon as i start the engine , the gets much softer and sinks about halfway.
also when i'm driving along, sometimes there's almost no pedal pressure at all on the first brake. but subquent brakes get better with each brake.
i've powerbled all 4 corners. no air. using ate super blue.
ideas?
with engine off, i can pump the pedal and get solid firm pressure. but as soon as i start the engine , the gets much softer and sinks about halfway.
also when i'm driving along, sometimes there's almost no pedal pressure at all on the first brake. but subquent brakes get better with each brake.
i've powerbled all 4 corners. no air. using ate super blue.
ideas?
10-17-2009, 09:09 PM
#2
Nordschleife Master
i'm not sure what's going on here.
with engine off, i can pump the pedal and get solid firm pressure. but as soon as i start the engine , the gets much softer and sinks about halfway.
also when i'm driving along, sometimes there's almost no pedal pressure at all on the first brake. but subquent brakes get better with each brake.
i've powerbled all 4 corners. no air. using ate super blue.
ideas?
with engine off, i can pump the pedal and get solid firm pressure. but as soon as i start the engine , the gets much softer and sinks about halfway.
also when i'm driving along, sometimes there's almost no pedal pressure at all on the first brake. but subquent brakes get better with each brake.
i've powerbled all 4 corners. no air. using ate super blue.
ideas?
10-17-2009, 09:14 PM
#3
Drifting
Thread Starter
oh man...the whole unit? or maybe just the fitting?
oh...i should also mention that i stripped out a whole alot out of the vacuum system. i got a line going from the intake manifold fitting going straight to the brake booster fitting.
oh...i should also mention that i stripped out a whole alot out of the vacuum system. i got a line going from the intake manifold fitting going straight to the brake booster fitting.
Last edited by krystar; 10-17-2009 at 09:32 PM.
10-17-2009, 11:54 PM
#6
Nordschleife Master
If you press hard on the pedal and hold it, will the pedal slowly go to the floor?
Your booster is fine. I'm betting on either a leak somewhere, or your master cylinder is shot. The seal between the front and rear portions of the master cylinder might be leaking, so its letting the pedal move down by just letting fluid pass from one chamber to another. It might also be leaking out of the rear seal, filling up the brake booster.
Your booster is fine. I'm betting on either a leak somewhere, or your master cylinder is shot. The seal between the front and rear portions of the master cylinder might be leaking, so its letting the pedal move down by just letting fluid pass from one chamber to another. It might also be leaking out of the rear seal, filling up the brake booster.
10-18-2009, 12:14 AM
#7
Instructor
Join Date: Sep 2009
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If you press hard on the pedal and hold it, will the pedal slowly go to the floor?
Your booster is fine. I'm betting on either a leak somewhere, or your master cylinder is shot. The seal between the front and rear portions of the master cylinder might be leaking, so its letting the pedal move down by just letting fluid pass from one chamber to another. It might also be leaking out of the rear seal, filling up the brake booster.
Your booster is fine. I'm betting on either a leak somewhere, or your master cylinder is shot. The seal between the front and rear portions of the master cylinder might be leaking, so its letting the pedal move down by just letting fluid pass from one chamber to another. It might also be leaking out of the rear seal, filling up the brake booster.
I have a similar issue but its cause my brake fluid was disgustingly black and even with a new master cylinder the pedal mushed... Im waiting on sourcing a better Clutch feed hose before i put the reservoir back on... I think im going to go get some nice new solid metal fuel line and flare the tips and just use pieces of the old blue hose to connect it between the two...
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10-18-2009, 01:54 PM
#10
Drifting
Thread Starter
ok did a couple more test drives around the block. i did notice something interesting. when going in a straight line, it didn't really matter how far or how long since last brake application.
however, if i did some slalom manuevers, it seemed to be repetitive. first thing that came to mind was wheel bearings. i replaced the fronts already. and yesterday when i had the car jacked up, there was no movement when i jiggled the wheel back and forth. the rears were tight too.
it didn't seem to matter on soft or hard application. i did a hard test driving in a back lot at 15mph and slamming on the brakes, it still went to the floor after my slalom manuever.
i'm gonna try to the reverse bleeding thing. maybe there is still air somewhere.
cheapest solutions first
however, if i did some slalom manuevers, it seemed to be repetitive. first thing that came to mind was wheel bearings. i replaced the fronts already. and yesterday when i had the car jacked up, there was no movement when i jiggled the wheel back and forth. the rears were tight too.
it didn't seem to matter on soft or hard application. i did a hard test driving in a back lot at 15mph and slamming on the brakes, it still went to the floor after my slalom manuever.
i'm gonna try to the reverse bleeding thing. maybe there is still air somewhere.
cheapest solutions first
10-19-2009, 04:04 PM
#13
Drifting
Thread Starter
holy ****. i found out the brake problem.
i went around and checked all 4 corners for wheel bearing again. i don't know HOW or WHEN. but my rear left axle castle nut is GONE.
what size and what thread is this? I need to get one today!!!
i went around and checked all 4 corners for wheel bearing again. i don't know HOW or WHEN. but my rear left axle castle nut is GONE.
what size and what thread is this? I need to get one today!!!
