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brake probs (searched)

H8PVMT

NAXJA Member
NAXJA Member
Location
Central Maine
so i spent the last two days mindlessly searching for a similar situation, here is mine. :geek:

Yesterday for no reason my brake went to the floor while driving, pumped it and it was fine, drove up until the supermarket parking lot and it did it again, then also as I was headed towards a HUGE drop-off. heres what I have tried:

checked the fluids
no leaks anywhere
had wife sit and pump breaks to listen for a leak
checked brakes (need new right side)
yelled at wife
drank beer

then I thought that all three times I had the tires turned about as far as they go when (or about when) they failed.

Is this normal?

specs in sig no ABS

thanks

doug
 
If its not leaking fluid anywhere, youve got a bad seal in the master cylinder. Those are really the only explanations for the pedal going to the floor.
 
so I'd imagine that they come back by pumping the brakes due to a build up of pressure sealing the bad seal?
 
Im trying to remember. Its been awhile since I had a MC torn apart but I think it has a cup shaped seal in it to allow fluid in one direction but not the other. Its possible that the seal could be worn or cracked and allow fluid by at low pressure and when the pressure builds it would seal against the walls of the cylinder better.
I dont know, I just cant think of another reason why your pedal would go to the floor. I mean its a closed system.
Wait, it could be air in the system, generally that just causes a mushy pedal though, but "mushy" could be construed as "going to the floor".
 
what about a rear brake cylinder?
 
EMSJEEP said:
what about a rear brake cylinder?

If the seal was bad in any of the brake cylinders, it would be leaking somewhere.
 
Ray H said:
If the seal was bad in any of the brake cylinders, it would be leaking somewhere.

Ok. I had a small leak that was impossible to detect after having just bled the system because of all the brake fluid around and the fact that it was sorta collecting in the drum.

Anyway heres my thread:
http://www.naxja.org/forum/showthread.php?t=917449
 
Check the wheel cylinders for leaks, but if no leaks, it's the MC. The rubber cups in a master cylinder are designed to expand outward under pressure, so when they wear they'll often let go under gentle braking, but hold all right when you pump or when you hit the pedal hard.
 
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