I'm having brake problems with my 55 Olds 88. I had a bad power booster, so I bought a rebuilt booster/master cylinder. I decided that I should replace the wheel cylinders and linings at the same time. I ordered the parts and when they came, nothing fit. Double checked the part numbers with several supply sources and they were correct for 55 olds. Apparently someone changed the backing plates and used other brakes. Anyone had this problem? Now my big problem is the booster. I installed it and could not get any fluid to the brakes to bleed. I finally pulled main brake line off of master cylinder and still could not get any fluid out of master cylinder after pumping brake pedal. What am I doing wrong, or do I have a defective rebuilt booster?
I'm not an experience mechanic at all, but thought I could use existing cylinders and linings until I figred what brakes I have. (anyone have suggestions on that)? Any help would be greatly appreciated. Thanks!

 

You need to bench bleed the master cylinder before installing it. Place the master cylinder in a vice and connect a clear flexable hose from the out let into the reservior of the master cylinder and push in on piston, repeat until all of the air bubbles are gone and you see nothing but brake fluid in the hose.

This is called priming the master cylinder. if no fluid moves then the master is no good

When you are through reinstall the master cylinder and bleed the brakes starting from the wheel farthest from the master cylinder, usually right rear, left rear, right front, left front. Make sure you keep the master cylinder full. Have a friend help you with this. install a clear hose on the bleed valve, make it long enough to go into a clear container with brake fluid in it. Have your friend pump the brakes 4 or 5 times then hold the brake pedal down. open the bleed screw and let the air out, close the bleed valve and tell your friend the to let the brake pedal up,repeat these steps until all the air bubbles are gone and you have clear fluid. Repeat at each wheel. This takes some time don't hurry it.

 

Thanks. As it is all one unit, booster and built in master, and has a fitting that main hose line comes into, it is rather difficult to bench bleed. Unit is already on car. Can I just unhook main brake line and pump pedal to bleed? I'm afraid the master is defective, and I am afraid I will hurt the booster pumping it dry. I'm kind of a over age novice and truly appreciate your help. I'm located in Baja California, Mexico, so it is difficult not only to get help, but get parts.

 

Yes, you can "bench" bleed the master cylinder with it on the booster. It is definitely better to have someone help, of course, and don't be too energetic with the pedal - just so the line doesn't get crazy and squirt fluid all over the engine bay :-)

 

It is kind of hard to imagine somebody changing the backing plates and shoes on this car. Is it possible the parts you got were the wrong parts in the correct box hence the correct part number. In any event you are wise to tackle one problem at a time. One other thing I would mention is to buy the special wrench used on wheel cylinders. I bought one years ago when I found out that even a good box end wrench can round off the valve on the wheel cylinder. There is no telling the last time these brakes were bled.

 

Thanks everyone for the help. I'll let you know how I come out. I did buy the line wrenches, or flare nut wrenches and had taken one cylinder off with no problem. But, the new cylinders didn't line up right for mounting. The new shoes have the same dimensions and arc, but the one plate on shoe is too long. I bought the parts from Napa-special order. Rock Auto and Autozone both had the same part numbers for the cylinders and the cylinders are what the car calls for. Mounts don"t line up...Weird isn"t it?

They could have made mistake with linings in wrong box...cylinders different story.