Brake bleeding question?

[jorgensensc]

Not on the truck, but the Bel Air. I'm having difficulty bleeding the brakes on the Bel Air (as always) For some reason they are not my forte'. They worked perfectly before My exhaust burned a hole in the rear brake hose. I replaced it and also painted the master cylinder while I was at it. Well I got it all back together and nothing leaks, however I can't seem to get the rear passenger side to bleed (drum). The front seem to bleed okay (discs) and the driverside rear seems to bleed okay. I have used my mityvac hand vacuum and my wife pushing brake pedal both, neither seem to be working on the passenger rear. When I have my wife put the car in reverse (off the ground) with her foot on the brakes and the parking brake on, the back tires still spin. The rear drums were adjusted correctly before the hose blow out. The parking brake won't stop the rear wheels at idle in reverse and the foot brake won't stop the rear wheels either. I have adjusted the rear drums to a point where they are hard to turn by hand when the car is in neutral and the p- brake is off. wit heth p-brake on I can't turn the rears by hand at all. Any ideas? I hate doing brake bleeding!! I just can't seem to get it right for some reason.
Shawn

[PanelDeland]

IIRC, the brakes are "self-energizing" meaning the trailing(rear) shoe's rotating motion increases the pressure on the leading(front)shoe.If the brakes are adjudted so tight you can't turn them then they are too tight.They should hold when the E-brake is on but not with it released.If you're nor getting fluid then there is something stopping brake fluid from getting to the wheel cyl.You may have a bad brake line,a clogged bleeder(if air can't get out then there isn't enough room for fluid to get in),or a clog in that brke lineor the junction between the left and right sides.I personally like using the one man bleeders whether I have help or not.It lets me see if there ar4e bubbles coming out of the bleeder.When they stop I know the air is out.
Just some more ideas to contemplate.
TTT maybe someone else will chime in.

[LONGHAIR]

Actually that is backward.
The front shoe is pushed away from the anchor point and it begins the self-energizing process by pushing against the rear shoe at the bottom. Since the shoes are tied together at the bottom, the rear pushes against the pivot point. The self-energizing effect is from the fact that the leading edge of the friction material is traveling the same direction as the drum, this creates a wedge effect. This is the reason behind the "short shoe" going toward the front of the vehicle. It takes some of the harsh/grabbiness away from drum brakes by lowering the point where first contact is made.

Many people falsely believe that the wheel cylinder pushes outward against both shoes and that they both move outward to make contact with the drum. In actuality the brakes would work with the wheel cylinder only pushing against the front shoe.........the problem with this is that it puts much more stress on the mounting point of the wheel cylinder. Having the wheel cylinder pushing against both forces the rear shoe to support the front and the pressure on the wheel cylinder's mounting point is nearly nothing.
I am always amazed by the amount of people that have no idea that the short shoe goes to the front....or that it even matters. I have taken many cars/trucks apart to find them backward or even mis-matched. (both short on the same side)

After all of that.......
I agree with PanelDeland, you may have some kind of blockage. Maybe a smashed line or a rusted wheel cylinder or blocked bleeder. Are you sure that you are getting good pressure on the driver's side? You mention adjusting the rear drums and you have discs on the front. What type of mastercylinder/proportioning valve do you have?

[jorgensensc]

Got it!
I Undid all the lines and blew air back up through the lines.Then had my wife pump the brakes until I had fluid at each connection! Than worked my way back to the rear wheel cylinders and got them bleed easily. The rear junction on the differential had no fluid in it before. What I thought was fluid on the driverside was just residual in the line. Got brakes again!!! Now I just have to finish the A.C. lines and charge the system!!! Even if the truck doesn't have A.C. yet the Bel Air will!!! Thanks for all the help everyone!!
Shawn

[LONGHAIR]

[PanelDeland]

Longhair,you certainly did a much better job of explaining the self energizing brakes than I.Thanks.