Drum brakes are from the DEVIL

[MadMez]

I lurk here alot but I now have a problem I could use some assistance with. My car is a 1968 Sport Suburban (Fury wagon) with 4 wheel power drum brakes. The brakes would not function properly so I replaced: brake booster, master cylinder, wheel cylinders, and brakes shoes. My issue is with the master cylinder adjustment rod (I think anyway). Following the advice of smart people I adjusted it so the M/C was about 1/16 to 1/8" from the booster. I found the brake pedal to be very low so I made the rod quite a bit longer and the pedal was much higher and the brakes worked like I though they should. I used it for local errand running and such and all was AOK.

I brought it to work today and about 2/3s of the way here the brakes started dragging pretty badly. Since I have this thing about not missing work I drove through them and smoked the new shoes but I got to work needing two feet to stop it. A tech let me use some of his tools and at luch I adjusted the push rod about 2 - 2 1/2 turns shorter. A quick test drive showed the brakes working, amazing I know, but with a low pedal again.

I am reasonably certain the brakes were bled completely so that should not be an issue. What is puzzling me is why did it change.

Can you fellows give me some advice for adjusting the push rod, and wheel cylinders? Should the self adjusting stuff be removed? Should I have my head examined?

I appreciate any info you can give me

Thanks

Tim

 

[bluefury361]

OK....... You have power disc brakes with shoes......?

I will assume you meant "drum" brakes.
Adjust the M/C pushrod to specs in the manual... (You DO have a factory manual....?)
The low pedal can be adjusted at each wheel by manually adjusting the shoes until a slight drag is felt when turning the wheel, (Wheel should turn about 3/4 turn when you spin & release). Wheel cylinders are not adjustable and the self adjustors only work to maintain adjustment once its set.

What happened is that the incorrect M/C rod adjustment caused the brakes to drag and heat up, which caused them to expand against the drum. Once brake shoes heat up they will fade and you loose braking power.
Likely they have become "glazed" from the excessive heat now and may need to be replaced to work right again.

Welcome and instead of Lurking..... Join in.... And WE require pictures of your wagon

 

[MadMez]

Here is the requested pic. It was taken outside my place of work to prove to my pals it moves again. It is strictly a beater but I love to drive it around. It is a hoot!

I do not have and will be getting a FSM sometime in the future. If I had one I would not need to communicate with you fine fellows

I very much appreciate the responce and will be working on it again this weekend, hopefully, with this in mind.