brake problem ... fronts ... master cyc

fj hunter · 06-27-09, 07:03 PM

I am having a problem with my front brakes. They lockup after a few tough stops, and when i bleed off the pressure down at the wheel where the bleed port is at, they have pressure on them with no peddle applied. is my problem with the vacuum assist or is it the master cyclinder the problem? maybe a check valve not letting go?

one small data point, i replaced the clutch cyclinder steel line today, and the vaccum hose was missing it's clamp where it attches to the vacuum assist, so i put on a clamp. could that be where the problem is at? was this releasing before since there was a leak there?

help please.

dargreg · 06-27-09, 07:09 PM

I,ve had problems with what they call a flapper,Which basically is a piece of the rubber hose breaking off inside which alows fluid to only run one way and act as a check valve the other way.Thats your rubber line from the houseing to the backing plate.

fj hunter · 06-27-09, 07:16 PM

and where is the flapping piece???

bsmith123 · 06-27-09, 07:51 PM

No, that is the vacuum hose--- he is talking about the fluid hose down near the brake.

The most common thing for the brakes locking up after a few pumps is the master cylinder rod being out of adjustment--messed with that lately?

green71fj · 06-27-09, 08:01 PM

inside the rubber brake line.could it also be the residual valve stuck.

fj hunter · 06-27-09, 10:31 PM

with the brakes lately. I did hose them off when i did my lockers front and back awhile ago, about mid April, have not driven it till today.

I inspected all the brake lines, and that was my first instint, that i had crushed a line wheeling this morning. lots of logs and brush. so i will start there again now that i am off the hill.

on a birghter side, my 8274-50 winch handled me nicely, as i got stuck on a muddy slope right at the edge of a 25 foot drop off, wheel were just 15 or so inches from the "oh no" part.

But, i made it out.

one more thing, when the front lockers are in, the power steering is not real good.

dargreg · 06-28-09, 06:04 AM

Ill bet with the front lockers in it wanted to drive straight didnt it.

fj hunter · 06-28-09, 09:04 AM

straight. wow. i had something else in mind, but the crawl was very very nice. the traction.

FJROSS · 06-28-09, 09:49 AM

When I purchased my 40, I had the same problem. They would release on there own after a few hours. What I found was that the previous owner never flushed the brake system and the fluid turn to a sludge and debris was in the master not letting the pressure to equalize. I ended up flushing the entire system and replacing the hoses.

Magnum44 · 06-28-09, 11:02 AM

There are quite a few things that could cause this. I assume (I shouldn't I know) your brake system is totally stock. When I was in the brake busyness I saw everything from tranny fluid in the brake system to drum m/cyl. used for disc brakes, collapsed lines, swollen hoses, contaminated brake linings etc. etc. If you have never flushed the system it would be a good idea anyway since brake fluid is hygroscopic (not hydroscopic) and will absorb moisture which causes the contamination, boiling etc. unless it's silicone. Anyway it probably wouldn't hurt to just go through the whole system and check everything.