[gtolockes]

I have searched several post and have read that you should put a phone book on the floor when bleeding the brakes to prevent the piston in the master cyl from going too far. Some indicate the M/C will leak from the back if you do. I installed a master cylinder and at first it seem like it had a hard pedal, until I realized the drum was off and the wheel cylinder had pushed the brakes way out. I reset them and now have no rear brakes.

I think the pedal was pushed to the floor and now I may have a problem with this. So I wanted to know... what exactly happens when you push the pedal to the floor... why does it leak, and can I take it apart and "reset" what ever I did to it?

Thanks,
Tom:

[67drake]

The reason is that crud builds up in the bore of the master in the areas that the rubber seals don't normally come into contact with. If you push the pedal too far the rubber seals on the piston get pushed into this rust/crud and it wrecks the rubber seals. If this happens you need a new master,or to rebuild the old one. Very simple to rebuild,but these days the rebuild kits are almost as much as a new master some times!
I have found the cheapest rebuild kits at Rockauto,BTW.

[gtolockes]

Thanks, I just pulled the lines off and made sure there was no air in it as it was brand new.. I have brakes now. I need to bleed out the system at the wheels a few more times. Just wondered why they say to put a phone book there to prevent this.

Tom

[67drake]

No problem.
BTW,when a master is brand new (or freshly rebuilt),you can push it as far down as you want. You just have to be careful of going too far with one that has had time to build up rust inside.