Rear passenger brake started dragging

1938FordPickup

1938FordPickup

Member
Had my 1938 for a long time, has juice brakes which never had an issue. About a month ago, rear passenger brake started dragging. Took it all apart, had a difficult time with getting the hub/drum off and readjusted the anchor points and wear cams back to zero. The drum/hub is difficult to put back on, will not turn or spin. Looked at the parking brake cable - loose, anchor points on the bottom are moving the shoes in and out, wear cam do the same. I can swap the driver side drum to see if the passenger side is warped. I need to check if the drum will go on without shoes.
Just looking for a few suggestions on what I can test to determine the cause. Up to about a month ago, no issues or troubles with the pickup.

Thanks in advance for your help.
 
I have never tested for a stuck piston in the wheel cylinder before, how is that done? I know there are 2 pistons with a spring in between, a seal and puck?
 
1938FordPickup said:
I have never tested for a stuck piston in the wheel cylinder before, how is that done? I know there are 2 pistons with a spring in between, a seal and puck?
Click to expand...

The parts inside wheel cylinder are just as you listed and look like this:
http://www.partsgeek.com/gbproducts...+Google+Base&gclid=CNj-5rKCwMgCFZOGaQodo7sHIw

Disassemble the brake shoes/springs and you will be able to "peel" the rubber seal off each end of the wheel cylinder to reveal what's inside. Below is what the 1940 Ford brakes look like. Yours may be similar depending if the originals have been replaced by Lockheed or Bendix style hydraulic brakes. In both styles the wheel cylinders will look similar and have a spring in the middle with a puck on each end followed by a big rubber seal that fits over each end of the wheel cylinder. The pucks slide back and forth pushing the inner seals against the cylinder bore while at the same time causing the shoes to expand against the drum. Depending on the condition of your wheel cylinder bore, you can buy wheel cylinder rebuild kits instead of new wheel cylinders. Contact Richard Lacy here on Fordbarn to make sure you don't buy inferior foreign made wheel cylinders.
 

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Yes, the pics are very similar to my rear passenger brake assembly. If the wheel cylinder is the cause of the dragging brakes, I will contact Richard Lacy about a replacement. The operation of the wheel cylinder seems very straight forward with how the seals and puck move. Could a broken internal spring inside the wheel cylinder cause the dragging (Prevents the puck from moving) ?
 
All sorts of things can cause a stuck or dragging piston, including rust, corrosion, or even just a few pitts in the bottom of the cylinder. The pistons are usually made of aluminum and can corrode, or even crack or break. The cylinders are very simple to take-apart, and to clean the inside surfaces and internal parts to be able to evaluate condition. DD
 
1938FordPickup said:
Yes, the pics are very similar to my rear passenger brake assembly. If the wheel cylinder is the cause of the dragging brakes, I will contact Richard Lacy about a replacement. The operation of the wheel cylinder seems very straight forward with how the seals and puck move. Could a broken internal spring inside the wheel cylinder cause the dragging (Prevents the puck from moving) ?
Click to expand...

A defective spring could do it in conjunction with a really dirty wheel cylinder. When did you last bleed your brakes? You may also have a defective brake line hose.
 
I will take the wheel cylinder apart this weekend to see what condition the inside is. Would a cleaning of the interior where the pucks and spring are fix this? Or is just better to buy a new wheel cylinder?
 
1938FordPickup said:
I will take the wheel cylinder apart this weekend to see what condition the inside is. Would a cleaning of the interior where the pucks and spring are fix this? Or is just better to buy a new wheel cylinder?
Click to expand...

You'll be better able to judge what to do once you dis-assemble the cylinder. Click on the link directly below for some brake tech, but also for some pictures showing some POSSIBLE ugly conditions that may be found inside brake cyls.

http://aa1car.com/library/2003/bf60330.htm

Here are a couple of pics showing the simplicity of a typical wheel cylinder, in pieces, and assembled. A basic, bare cylinder is nothing more than a clean, smooth, hollow metal tube. DD

799px-Wheel_cylinder_Child_parts.jpg


Wheel_cylinder.jpg
 
You should also check the little horseshoe clips that hold the parking brake cable return spring under tension. They're pretty flimsy and if they disintegrate, can allow the parking brake shoe to drag, even if the parking brake handle is in the "off" position.
 
Folks ... We have a winner and it is ... rheltzel !

It was the parking brake spring retaining clip, somehow it broke and a very small piece jammed inside the tube that the parking brake cable runs through. This acted as a "one way check" preventing the parking brake cable to return it's normal position. Had to pull hard on the cable to pop out the small piece from the tube. Just need to adjust the anchor points and cams to finish the job.
 
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