brake problem!

[kakswell]

Hey, so ive got an issue that i need help with... basicly my brakes are soft and only come on half way down!

Ive basicly Drivin home form work brakes where fine! hour later ive jumped into the car and brakes went soft n only come on half way down! so i re bled them no change.. so far ive replaced Front hoses and put second hand front and reer calipers on and installed a brand new master clynder.. and my problem hasnt changed.. the reer hoses when being pumped dont seem to have any bubbles or any sus that i could feel .. i did take it to a "brake specialist " who inspected and took it for a test drive and said he doesnt know what the issue is and basicly didnt wanna know! so Any idea's Please! would be much aappreciated thanks!

[ryan21]

sounds like brake booster have you checked the vac hose from the engine to it? also you could try pumping the brake till its hard when the cars off then press the pedel in when you start the car.

[kakswell]

would i be lookin for splits ?? also i forgot to mention i replaced pads and rotors and that did make brake pressure normal for a few days till it went soft again.. when i pump the brake when car is off it doesnt pump back to the top basicly pumps a bit higher than what it is when car is off

[ryan21]

so when you pump it when its off it doesnt go hard, just a bit harder than when its on? could be a vac leak i would just change the hose go down to repco or bursons bring the hose with you ask for that length and get some better hose clamps while you're at it as well, i took it off there, took it to them and then fitted the new one in the carpark. if the problem is still there it's probably the booster if you have a v6 the 5L booster/cylinder is worth the upgrade they regularly go on ebay for like $50. might make it quite sensitive unless you get the 5L calipers too, but they are worth it as well.

[Not_An_Abba_Fan]

Doesn't sound like a booster issue, if it was, the brake pedal would pump up with the engine off.

When you apply the brakes, do they grab and pull up really quick? Even though the pedal is low?

[markovr]

Had the booster diaphram go with my old vh and it did exactly the same ...my son was driving it a the time and I said "surely you could drive it home" but after seeing how shit it braked Im glad he didnt.I took apart and there was a slight tear in one diaphram and over time the master cylinder had leaked a lot of fluid into the back of it so when we took it out and tipped it up a lot of fluid came out of it.

[Not_An_Abba_Fan]

The master cylinder would have been stuffed if it leaked, they shouldn't leak at all. The bad braking would have been a combination of a stuffed M/cyl and torn diaphram in the booster. A buggered booster will only make the pedal hard and take longer to stop as you will have no vacuum assist.

[kakswell]

at the moment the peddle is really low when its cold and stiffins up a bit after 5 minutes of driving, just before half way down u feel brakes start to have effect but half way down is bout when brakes are doing anything and almost 3/4 down to get the car to slow down

[kakswell]

Doesn't sound like a booster issue, if it was, the brake pedal would pump up with the engine off.

When you apply the brakes, do they grab and pull up really quick? Even though the pedal is low?

if i get on the brakes really hard.. it doesnt lock up and takes along time to pull up

[Not_An_Abba_Fan]

You could try resetting the safety switch in the master cylinder, where the plug is on the side (or bottom?) remove the plug and undo the switch until you hear a click. Do it back up and re-attach the plug. If that doesn't work, your master cylinder is rooted.

[kakswell]

You could try resetting the safety switch in the master cylinder, where the plug is on the side (or bottom?) remove the plug and undo the switch until you hear a click. Do it back up and re-attach the plug. If that doesn't work, your master cylinder is rooted.

master cylinder is a day old! just brought it brand new from repco and ive got the same symptoms as i did with the one i just took out that i picked up from the wreckers

i might for what its worth.. go wreckers and get another booster just to eliminate that .. than that just leaves me with the 3 reer hoses , i read somthing bout hoses collapsing on the inside but causes brakes to stick on? i dunno. im runnin out of idea's with this thing

[Not_An_Abba_Fan]

Maybe the bleeding process needs to be done differently.

The proper way to bleed the brakes is to start at the left rear, using a clear hose attached to the bleeder to see the air bubbles.

Open the bleeder, push the brake pedal down, close the bleeder., release the brake pedal. Repeat until the fluid flows with no air bubbles.

Move to the right hand rear and repeat the same process. Then go to the left front, then the right front.

Did you bleed the master cylinder before you fitted it? Sometimes they can get an airlock in them, but usually bleeding at the wheels will get it all out.

When bleeding, do not pump the pedal up as this just aerates the brake fluid. Using the above method pushes the air along the brrake lines without agitation.

[kakswell]

yeah thats how i bled them with the tube, except the doin up nipple after each pump... why would replacing the rotors cuase a perfect peddle for a few days than to go back to half way down.. when i mean half way down there is only Minor pressure and starts to firm up about half way but not enough to stop my foot hittin the floor when i push it hard enough .

at 100 if i push it as hard as i possabily can it doesnt come close to locking up..

[Not_An_Abba_Fan]

Air in brake lines cause all different sorts of reactions.

Bleed them again using that method and see how it goes.