Brakes dragging
Thread Starter
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Cross-Country
Joined: Jun 2017
Posts: 91
Likes: 1
From: South of Yankee Territory
Brakes dragging
Hi all,
I've got a 1961 F250 unibody. A few weeks after I got it a bad rear wheel brake cylinder resulted in a no-brakes situation. Replaced both rear cylinders and one hard line that was destroyed getting it off the old cylinder. In the process I squirted the brake assemblies off with brake cleaner but didn't do anything to them at the time, as they seemed to grab fine. Never got it bled quite right, so the pedal's a bit squishy, but I don't think that's relevant to the situation.
Anyway, the issue is that while driving I can hear a low-volume, high-pitched squealing, that I can only assume is one or more brake shoes rubbing. It sometimes goes away if I tap the brake pedal, so I guess a shoe is not retracting fully? What would cause this, and what exactly should I be looking for before I jack it up and start pulling wheels off?
Thanks.
I've got a 1961 F250 unibody. A few weeks after I got it a bad rear wheel brake cylinder resulted in a no-brakes situation. Replaced both rear cylinders and one hard line that was destroyed getting it off the old cylinder. In the process I squirted the brake assemblies off with brake cleaner but didn't do anything to them at the time, as they seemed to grab fine. Never got it bled quite right, so the pedal's a bit squishy, but I don't think that's relevant to the situation.
Anyway, the issue is that while driving I can hear a low-volume, high-pitched squealing, that I can only assume is one or more brake shoes rubbing. It sometimes goes away if I tap the brake pedal, so I guess a shoe is not retracting fully? What would cause this, and what exactly should I be looking for before I jack it up and start pulling wheels off?
Thanks.
Tuned
Joined: Mar 2019
Posts: 401
Likes: 39
From: Wallyworld, VT
Maybe a piece of rust bouncing around in there?!? Drum brakes maintain a few pounds of pressure, I read here as much as 10lbs, as I understand it to keep them close to the drums as they wear so the pedal stays firm. I was always taught to adjust the shoes so they rubbed slightly when you spun the wheel, with the extra pressure they are probably rubbing pretty well most of the time.
Lead Gopher
Joined: Aug 2012
Posts: 10,067
Likes: 1,622
From: Seattle
There are retracting springs inside that help with pulling the shoes away from the drums. Those springs can weaken over time and sometimes get stretched during removal and installation. There is also likely, or should be, a spring on the ends of the emergency brake cables. This spring helps with pushing back the parking brake operating lever which pulls the brake shoes into the drums.
If those long springs have broken or are missing that can play a role, too.
If the wheel cylinder is not retracting - if it is sticky - that can contribute.
I'd also try to get a good bleed on the system - if there is air in the system it can affect both applying and releasing.
If those long springs have broken or are missing that can play a role, too.
If the wheel cylinder is not retracting - if it is sticky - that can contribute.
I'd also try to get a good bleed on the system - if there is air in the system it can affect both applying and releasing.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Weak springs, they lose their tension, also the backing plate has those raised pads for the shoes to slide on 3 ea. per shoe. With long use these become gouged and the shoes can hang up and not retract smartly.
Cargo Master
Joined: Oct 2005
Posts: 2,084
Likes: 94
From: Stanton, Michigan, USA
What is the age of the brake lines? If they're are more than three years old with limited use, they may have collapsed internally, causing the brakes to act like they are 'hanging up' and not releasing....... It may be easier to change the brake hoses than have them hang up and then you end up dragging on a corner and cooking an otherwise decent cast-iron brake drum....
BarnieTrk
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Joined: Jun 2003
Posts: 3,928
Likes: 276
One-line, jar type master cylinder is an extremely scary brake system. Many years ago, I too blew a rear wheel cylinder and wound up driving through a Pontiac Sunbird.
Upgrading the brake system was the best thing I ever did to my Unibody. I found some used aftermarket brackets and calipers on Craigslist, rebuilt the calipers, installed a FT7 brake booster with a ‘76 disc/drum master and a ‘76 combo valve. For the rear I scavenged backing plates and axles from a ‘69 F100 resulting in wider brake shoes and more modern self-adjuster hardware.
The booster/master setup was a direct bolt in using ‘72 booster brackets and my original pedal linkage.
Upgrading the brake system was the best thing I ever did to my Unibody. I found some used aftermarket brackets and calipers on Craigslist, rebuilt the calipers, installed a FT7 brake booster with a ‘76 disc/drum master and a ‘76 combo valve. For the rear I scavenged backing plates and axles from a ‘69 F100 resulting in wider brake shoes and more modern self-adjuster hardware.
The booster/master setup was a direct bolt in using ‘72 booster brackets and my original pedal linkage.
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Lead Gopher
Joined: Aug 2012
Posts: 10,067
Likes: 1,622
From: Seattle
Don't forget if you have a manual transmission you can slow down a lot using the gears and there is also the emergency brake (parking brake) and the steering wheel. A lot of people panic and freeze in a situation. I suppose if a person is following too closely they may not have any time to react. I give a good cushion and drive the truck like it is an old truck - which it is. Thing to do is to drain the master cylinder on purpose and learn how to drive it like that.
Thread Starter
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Cross-Country
Joined: Jun 2017
Posts: 91
Likes: 1
From: South of Yankee Territory
Thanks for the suggestions everyone, FTE truly is the best.
Looks like my first step is to try to actually bleed the system correctly, and see if it's something as simple as that. Failing that I'll tear into the drums and see if anything's hanging up, etc, per y'all's suggestions. If that doesn't solve it I'll move on to replacing the rubber lines. I have no idea when they were last replaced, so that could be it.
I'll agree on the heeby-jeeby factor of driving a system that goes kaput at the least leak, but I do try to give everybody a lot of space, slowing down way before I need to and not even using the brakes. Fortunately it's pretty flat around here. At least it is a manual. If worst comes to worst I can grind down through the gears and get it stopped. With the low rear-end ratio first is slower than that 5 MPH bumper limit on modern cars anyway.
I'll make note to completely go through the brake system before taking it over wolf creek pass.
Looks like my first step is to try to actually bleed the system correctly, and see if it's something as simple as that. Failing that I'll tear into the drums and see if anything's hanging up, etc, per y'all's suggestions. If that doesn't solve it I'll move on to replacing the rubber lines. I have no idea when they were last replaced, so that could be it.
I'll agree on the heeby-jeeby factor of driving a system that goes kaput at the least leak, but I do try to give everybody a lot of space, slowing down way before I need to and not even using the brakes. Fortunately it's pretty flat around here. At least it is a manual. If worst comes to worst I can grind down through the gears and get it stopped. With the low rear-end ratio first is slower than that 5 MPH bumper limit on modern cars anyway.
I'll make note to completely go through the brake system before taking it over wolf creek pass.
Cargo Master
Joined: Oct 2005
Posts: 2,084
Likes: 94
From: Stanton, Michigan, USA
When doing your inspection of the braking system, know that the OEM steel lines DO RUST OUT TOO!
But where? I've found the steel lines to rust out at/under a frame clamp.
So, once you've bled the system thoroughly, let it sit. The next day, crawl under it with a good flashlight and inspect each line clamp for any dampness that might emerge from the line pressurizing task the day before.
Good Luck and keep us informed with your progress!
BarnieTrk
But where? I've found the steel lines to rust out at/under a frame clamp.
So, once you've bled the system thoroughly, let it sit. The next day, crawl under it with a good flashlight and inspect each line clamp for any dampness that might emerge from the line pressurizing task the day before.
Good Luck and keep us informed with your progress!
BarnieTrk
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