My rear passenger drum feels like it's dragging. I pulled it off earlier and the cylinder expanded so that I couldn't fit the drum back on until I bled the line some. After I bleed it, it seems ok until I hit the brake again.

Do I still have air in that line, or is something else going on?

 

What truck?
Stock system?
If modified, how?
Known condition of the brake system.........How long since rebuilt?

Maladjusted master cylinder push rod.
Bad brake hose internally.

 

48 F1. System is stock configuration with the exception of the rear end, which is a 9".

I just replaced the rear wheel cylinders, and the master cylinder cap and gasket. Everything else is the same as when I got it a few months ago. The brake lines look to be fairly new.

 

Check your brake pedal free play. you need at least a half inch. good luck

 

If it's only the one wheel that's giving you the problem, you may have a weak return spring (the spring that retracts the brake shoes after application)

A drum brake master cylinder has a check valve that keeps 10lbs of pressure applied to the wheel cylinders. A weak return spring will allow this pressure to expand the brake shoes with the drum off.

You could easily check this by swapping the return springs (left r/s to right wheel) or buy a "brake hardware kit" (new springs) and see if the problem still exists.

 

Yup ! That's my take also. Spring Kits aren't expensive and available.

 

I agree that weak springs would be a logical diagnosis. It should be easy enough to check as you should be able to push the shoes back into position by hand with the drum removed. But your first post almost sounds like you can't do that? When you installed your 9" rear end did you replace all the lines and hardware? I'm assuming that you are still using the originals single chamber master cylinder? If you didn't replace the lines and hardware check for a proportioning valve or ABS rear shutoff valve (I'm not sure how new your 9" axle is).

Then of course I'm assuming that you checked your emergency brake cables?

 

Thanks everyone for the replies.

The 9 inch was installed by a previous owner. I acquired the truck early this year. I haven't replaced any of the brake lines. I'm still using original style single chamber master cylinder.

I had the parking brake disconnected while I had the drum off. I was not able to push the shoes back into position. I had to bleed fluid off before it would compress.

Encountered another issue after I drove it a short distance yesterday. The brake pedal became extremley hard with little to no travel. The brake lights were stuck on. I opened a bleeder long enough to relieve the pressure and they turned off.

 

Sounds to me like the inside of a rubber brake line has separated and has
a flap that is working like a valve. I have seen this a few times. The only way to release the problem brake is to open the bleeder or brake line.

 

It reads like you have a check valve in the system somewhere (assuming that you have no booster on the master cylinder). Here is a link so you can see the different kinds:
https://www.google.com/#q=ford+proportioning+valve

It could be mounted anywhere along the line. Some types have a brake light switch incorporated and some need to have a plunger depressed when bleeding the brakes. Here is a little more info that may help you.
Brake System Proportioning Valve | Function Diagnosis

 

I've been doing some research via google, and I was beginning to suspect this. I'll try replacing them next.

 

After replacing the return springs, my issue appears to be resolved. Thanks again for all the suggestions.

While I was working on it, I replaced the hold down cups/springs/pins The kit I ordered contained this clip:



I have no idea what I'm supposed to do with it. I couldn't find anything like it on my brakes, so I assume it's purely decorative.

 

that clip is what holds the emegency brake assy together.

 

Ditto , it holds the emergency brake lever to the rear brake shoe .

 

You gotta be kidding!

91A-2106 .. Retainer-Parking Brake Operating Lever Pin / Available from Ford

Applications: Multi-millions of 1939 thru today FoMoCo vehicles!

Illustrated in upper parts catalog pic as 2106