Master Cylinder sucked dry... Now What??? Quick?

[elks]

So I have been wrenching all weekend trying to get to Moab tomorrow. I have replaced front and rear brakes.All sorts of crap both of my wheeling vehicles have had major failures....

In the process I pulled a total newb mistake and let the front resivoir get sucked dry (heck it might have been close to dry already) Well now were getting no place bleeding the brake. How do I bleed the master cylinder? It is a 1972 K5...

 

[Fordum]

Well, you may have damaged the seals in the MC, or there is an air bubble blocking something somewhere.
To bleed a MC, you usually get two short pieces of brake line with fittings that will fit the ports, take loose the regular lines, hook up these two and bend them up and around so they point back into the MC.
Then give it long slow stokes letting the fluid go back in the top until you have all the air bubbles out.
But in this case, you can probably just fill the cylinder and loosen the lines and it will gravity bleed the MC.

Then just bleed the lines normally.

If you are not getting fluid to either the front or back, the proportioning valve may be stuck.

 

[elks]

SO I got the mc bleed and things felt good. Bleed the lines and it seems ok but drove it a dozen times and was not filling as well.

How well can I expect the brakes to work on the blazer with 36x13x15 tires? It has never stopped really well, almost scary like....

Now when it does stop the front seems to dive harder... Did I not get my rear brakes adjusted out enough? Thanks all

 

[Russell]

Front brakes should lock up before the rear brakes. Rear locking up = out of control skidding.

Are you running stock axles? Upgrading to bigger 3/4 or 1 ton brakes means you would benefit from the matching master cylinder.

My Tahoe had really bad brakes until I swapped on a proper disc disc 1 ton master cylinder. It now locks them up at will with ease. My problem is that my rears stopped harder than the fronts, meaning my truck would always kick the back end out during a panic stop. I swapped the d60 calipers out with a set of 3/4 ton 10 bolt calipers like out back, hoping my proportioning will be better now

 

[496truck]

You will most likely need to bleed the rear brakes some more, especially if you had the m/c bleed out. That's a long line from the m/c to the rear and it can take a while to bleed. Try bleeding it some more.

And x2 on the bigger brakes. The 3/4 ton brakes on my K5 will put you through the windshield.