help with brakes????

[zach4564]

ok im new to this thing dont realy know what in doin, but i have an 87 n/a and i replaced the brake master cylinder b/c it was leaky after that my pedal is still soft i push it too the floor then at the very end it locks up the front tires?? please help thanks

 

[IJ.]

Zach: Did you bleed the brakes?
(I edited the spelling to make it easier for the guys to help you)

 

[supramacist]

hello zack??????? Did you bleed the brakes???

 

[zach4564]

ya i the shop i took it to gravity bleed them then ragural bleed then when they changed out my proportion valve and when we did my mc.

 

[supramacist]

Personally, I always do my own brakes. It's easy enough. You need to back off the pipe before you come in here. As far as your car goes, I'm staying out of it for the time being. If you payed someone to do your brakes....., TAKE IT BACK. Especially if your'e not happy

 

[xarewhyayen]

Im not even sure you know what you're typing. Gravity bleed doesnt do shit when you replace a master cylinder. Take it back to the shop that did it. If it was you that did the master cylinder, did you bench bleed the master? I'd recommend having it all done correctly and having the whole system pressure bled/flushed.

ya i the shop i took it to gravity bleed them then ragural bleed then when they changed out my proportion valve and when we did my mc.

 

[Yellow 13]

What is bench bleeding Ive heard it come up a few times but noone ever explained how to do it.

 

[supramacist]

Stay out of this one yellow, it's no good for you.

 

[xarewhyayen]

you basically take the master cylinder, put plastic plugs where the brake lines would go, and attach tubes to those plugs. You then put those hoses from the plugs to the inside of the resivoir and fill the resivoir with brake fluid. you take a screwdriver and pump the master cylinder until bubbles stop coming out of the tubes. Its sort of like priming the master cylinder. It gets out all of the air. Very much not as technical as it sounds.
edit: im pretty sure many if not all new master cylinders come with the bench bleed plugs n hoses

 

[xarewhyayen]

Stay out of this one yellow, it's no good for you.

Take it ez man the guy wants to learn

 

[zach4564]

i did do the mc my self and i did bench bleed it and i also do most of the work to my cars just wondering if any one knew somthing i didn't????

 

[xarewhyayen]

well a spongy pedal means a couple things.
1. a fluid leak
2. air in the line
3. bad master cylinder seals.

you eliminated #3 if you replaced the mc. now just check for any leaks. If no leaks, id say stop beating around the bush and have the whole system pressure bled.

 

[zach4564]

where could i get that done?? any shop????

 

[supramacist]

I have been speaking to yellow for a bit. I just didn't want you blasting him, like you did that other Member. I hope he didn't take it personally. I could have worded it differently.

<edit IJ> try not to make things worse with name calling please.

 

[xarewhyayen]

haha supramacist. i see. and zach, yes most shops should have pressure bleeders. Its basically a tank with a bladder in the middle. You put ~25 psi of air in the bottom and the top of the bladder is filled with brake fluid. u put the right fitting on ur resivoir and it pressurizes ur brake system @ 25 psi of fluid. All they have to do is open ur bleeders 1 by 1, until the fluid comes out dead clean, then close the bleeder. furthest wheel from abs to closest. Not only is it a failproof way to get air outta the system, but it flushes all the old brake fluid. One of the single most neglected parts of any vehicle. I flushed mine 2 weeks ago and DAMN was that some nasty fluid. Brake fluid is hygroscopic which means it absorbs water. Water and rubber dont mix. When you absorb alot of water not only does it corrode rubber brake lines, but it also lowers the boiling point of the brake fluid ( if it boils, You get air in the system!)

Edit: hygroscopic..not hyDroscopic oops

 

[supramacist]

My bad, All Apologies.

 

[bluemax]

I read somewhere its recommended to change brake fluid every year.
But I don't know anyone that does. Water gets into the system through the seals and starts corrosion and of course you loose compressibility of the brake fluid too.

 

[xarewhyayen]

Im not positive about exactly how often you should change it, but probably every year or 2. The fluid itself will not lose its hydraulic capabilities. you cant say it will lose its compressability, because liquids wont compress. Thats why brakes work. Hydraulics work because in a confined space, a liquid can transmit pressure without loss. Adding water to brake fluid does not change that, but it does lower the boiling point, increasing chances of getting air in the lines and increase the wear of the parts inside the system increasing chances of failure.

 

[bluemax]

The reason you use hydraulic oil instead of water in the brake lines or anyother hydraulic system is for compressability. Fliuds compress just like anything else.

Although I don't know how much compressibility you loose because of only a few percent of water in the lines.

 

[Joel W.]

The fluid itself will not lose its hydraulic capabilities. you cant say it will lose its compressability, because liquids wont compress. Thats why brakes work. Hydraulics work because in a confined space, a liquid can transmit pressure without loss. Adding water to brake fluid does not change that, but it does lower the boiling point, increasing chances of getting air in the lines and increase the wear of the parts inside the system increasing chances of failure.

Agreed..