When you let off the pedal, is the master cylinder suppose to be totally disengaged, or should the rod still excert some presure on the cylinder?

Patrick. Fully retract, no pressure. A manual setup uses a spring to retract the pedal.

Rob

I do have a manual system. I had replaced the MCyl. twice, and bled the brakes to no end. What was happening was I could pump the brakes up, but then they would go to the floor. I found that by applying very slight pressure on the pedal, I mean very slight the pedal would stay firm. I still need to tweak it a little. I can sit in the wagon with it in neutral and get the the beast to move with one foot on the ground. I then cranked her up, went forward back etc., brakes seem fine. I will play with the fine tuning another day. Anyway thanks for the help.

Patrick.

Look at is this way. If the system is closed, correctly setup and with no air inside, the only reason you would have to pump up pressure, is that the M/C will not displace enough fluid.

With rear brakes (or even the front) out of adjustment, pumping up may be needed.

When the M/C is bad, fluid is pumped around; but I understand that one has been replaced 2 times already.

Are you using slicone fluid (dot 5) ? It tends to hold air in very small bubles.

Could it be the M/C is a more modern type, with some valve inside?

I found that by applying very slight pressure on the pedal, I mean very slight the pedal would stay firm. I'm not sure I understand all you are saying. How do can you "feel" a firm pedal by applying "light" pressure?

Rob

When I pump the brakes up, and apply presuure to the pedal, the equivalent of about 3/16" movement the pedal will stay firm, remove this slight pressure, or even call it increasing the legth of the rod by this much and the pedal will go to the floor.

In a disc-drum setup the metering valve blocks the front in favor of the rear. When the rear linings meet the drum, the valve is opened for the front. This would explain the effect you have. Even then the M/C would be at fault. Knowing this is your second (or even third) M/C what could be chance it is at fault?

Maybe your lines are reversed with respect to this perticular M/C?

Rob

Well the small sump is in the front, and it is going to the rears. The large sump is in the back, by firewall and it is going to the front brakes(disk). The lines are run correctly to the prop. vlv. and to the wheels. So I don't know. i did have one cyl. in there that had the sumps the opposite way around. Same prob. The washers as spacers seem to be working fine, I have not drove it for any distance yet though, end of drive and back. Left a few black marks on my wifes red stained driveway, she councelled me on this. Oh Well told her it should be black and white check, before she stained it before.