what just happened to the brakes?

[adymeblack]

So i was taking my car to a suitable place to work on it and came across a problem. I was going down a hill and while i was sitting at a light all of a sudden the brake pedal just sunk to the floor, and i lost my brakes. Hasn't done it since, of course i haven't been driving it because i'm replacing the rack and pinion and it's being difficult.

see this thread if your interested in the rack complications...
http://www.cb7tuner.com/vbb/showthread.php?p=2464303

[evil_demon_01]

Either the Mastercylinder is faulty - The seals inside are worn and bypassing.
Or there is a leak somewhere.

More than likely its the mastercylinder - common fault, get it replaced asap.

[415cb7]

I agree with evil. My car's brake pedal would sink slowly and after about 25 seconds, the car would start rolling forward. After the master cylinder was replaced, the brakes worked fine.

[adymeblack]

I was afraid of that.......

Is there a way I can test the master cylinder to see if it is faulty?

[19dabeast85]

Is there a way I can test the master cylinder to see if it is faulty?

Yes, if you're sitting at a light and your pedal sinks to the floor and you lose braking pressure then your MC is bad, you already performed the best test procedure for it, replace the MC.

[bmxboi23]

Yep, that's a good sign that your MC is bad. Beyond that you can check for fluid on or around it. You can also press your pedal down with the engine off and start the car while holding the pedal. If it drops significantly then you have your answer. Note* this test alone doesn't positivly mean your MC is fail(ing) it can also mean the breaks just need bled. However replacement is fairly easy and very basic. Schucks/Oreillys sells remanufactured ones for as low as $50+ core.

[adymeblack]

Yeah, I guess you guys have a few good points.....of course it can't something simple like needing to be bled.

If I replace the mc, do I have to replace the booster along with it?

Well, looks like I get to see james at my local auto parts store.......again

[19dabeast85]

Yeah, I guess you guys have a few good points.....of course it can't something simple like needing to be bled.

If I replace the mc, do I have to replace the booster along with it?

Well, looks like I get to see james at my local auto parts store.......again

Not necessarily. Sometime when the MC fails it'll let brake fluid drip down into the booster, if this is the case the fluid will eat through the booster over time. When you remove the MC, check behind it and down inside the booster for wetness/rust. If you see nothing then your booster should be fine.

[adymeblack]

Ok then, ill check into it tomorrow while I'm working on the rack and pinion

[adymeblack]

How difficult would you guys say replacing the mc is? I'm trying to decide if its worth it to pay someone to do it for me.

[evil_demon_01]

How difficult would you guys say replacing the mc is? I'm trying to decide if its worth it to pay someone to do it for me.

Undo 2 10mm brake pipe nuts, and the main 12mm bolts that hold it on.
Bench bleed the new one then fit it back on, and bleed the brakes.
Overall I'd say its a 4/10 in terms of beginner job.

However if you are unsure, or don't have the confidence - Get a shop to do it.
Brakes are a safety issue, If in doubt - get a professional to do it.

[adymeblack]

Ok, i think i can handle that. After i replace the r&p i have to take it to the shop to be aligned anyway, i can have them check over my mc work to make sure everything is kosher.

The only 2 things my dad ever told me about cars: "Don't f*$k around with the steering and the brakes, you must have a solid illusion that you are in control of the car."

Thanks guys

[adymeblack]

Changed up the master cylinder and the brakes are doing ok, had to replace the rear pads because I guess the person that put them on before didn't put them on right and one was put in cock eyed, got the rotors resurfaced and they are working just fine.