if the rear brakeline is leaking very badly, does that affect the front brakes too?

thank you

 

No and Yes. No it won't affect how the front brakes function. But if it's bad enough it could cause the car to pull to one side or lose rear brake function which would cause you to take longer to stop. But they are totally separate systems. As long as your brake warning light isn't coming on you should be fine.

 

thats weird, because im changing the rear brakeline, and my front brakes are now not working at the moment (with the brakeline open)

im not driving it, im just testing it in my garage

 

Is the MC cover off?

 

Some GM combo valves (proportioning) are designed to pressurize the rear line before the fronts. The rears have to build resistance before the fronts will be fed.

Fix and bleed the rears, go from there.

 

With the rear brakes open or leaking badly you won't have any pressure at all in the front brakes until the piston in the combo valve is at full travel, which takes a considerable amount of pedal travel. Even after that you probably won't have much pressure in the fronts before the pedal bottoms out.

 

okay, that's explaining everything. thank you

 

just FYI since you didnt say where you took the line off at...

the rear of the master cyl feeds the front brakes, and the front of the master cyl feeds the rear brakes