hey i got a question about brakes on a 73 mustang with rear drum and disk front brakes, the brake pedal is very soft and it goes to the floor while brakeing, i have checked that their is fluid, i have bled the brakes many times and there are no leaks to my knowledge, i am wondering what the problem is.


-Justin

 

How old is the fluid? Once it's been in there/beat on for a while it gets past the point where it can absorb water and gets water buildup in the line, that can turn to steam and compress, and it will also break down and turn to junk. Also, it is possible to have a leak small enough that not enough fluid comes out for you to necessarily notice it easily, but it can still pull air back in. The master cylinder may need replacing as well, they have internal seals that eventually fail over time/use.

 

Look at the master cylinder for wetness. This can be at the firewall (or booster) running down the backoraround thelittle hole in the bottom of the MC itself (may not have one). As the o-rings wear out, it can bypass.If the pedal is firm, then goes down slowly, itsmost often a leak. If itgoes to the floor then pumps up to a firm pedal, then its most often air.Also, if the master cylinder wasn't bled before installing you could have air in it. If you haven't replaced it, now is a good time,they are usually under 20 bux with a trade in of the old one at most chain stores. A real good investment. Are the rear wheel cylinders good? You can check these by removing the drums, otherwise its hard to tell unless its driping out the bottom. Also if you replace the system, you may want to consider a modern silicon brake fluid like DOT 5 (not 5.1). Just remember that it will not mix with glycol type 3 or 4 fluidsand the system has to be evacuated before you install it.

 

i also heard from a friend of myne that it is the master cylinder, i am deffinetly going to get a new one of those next week and i will check for the leaks around the firewall, thanks

 

Yep it sounds like the master cylinder