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Discussion Starter · #1 ·
1992 Bronco, 351W, 230,000 miles

The Problem: The brakes operate fine at first, but after a random amount of distance city driving (3 to 20 miles) the right rear brake will start to drag slightly. Once it starts dragging, it progressively gets worse and eventually gets hot enough to smoke. The left rear brake doesn't have this problem. After sitting for anywhere from 5 to 15 minutes, the brake will release and I can continue driving. When it releases, I hear clicking sounds from the right rear wheel. The Brake Warning lamp and ABS Warning lamp light up in strong correlation with the brakes dragging, but sometimes the brakes drag without the lights coming on.

Repair 1: I replaced the calipers and turned the rotors on the front disc brakes. I replaced a rear drum (can't remember which side), turned the other one, and replaced the cylinders on each side. I then bled the system: right rear, left rear, right front, left front. The brakes tested fine initially and the RABS system worked fine. (I felt the brake pedal pulse to prevent the rear wheels from locking up.) The problem did not go away.

Repair 2: I treated the warning lamps as a separate issue and replaced the master cylinder. I cleaned the integral proportioning valve thoroughly. The warning lamp issue has decreased in frequency dramatically, but has not gone away completely. It has happened once in the 6 days since, while it was happening on a daily basis before. The right rear brake still drags, but not as often.

Repair 3: I bled the system to thoroughly flush out old brake fluid making sure clean fluid was at each bleed valve: right rear, left rear, RABS valve, right front, left front. This was the first time I had ever bled the RABS valve. I've not yet seen the warning lamp problem. The right rear brake still drags, but only after driving more miles.

Any ideas? I think my next steps are:
  1. remove the drum and inspect the linkages for binding
  2. inspect the e-brake line to the right rear for binding
  3. Check right rear hydraulic line for blockage. It's steel, though, so I don't know how that could happen.
  4. Remove, inspect, and clean the RABS valve. This thing is very expensive at the Ford parts house.

I appreciate any ideas y'all have!
 

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Satyr of the Midwest
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Are your automatic adjusters backing out on you? If so, it could be that the little steel pawl isn't resting against the adjusting wheel spokes, permitting the adjuster to expand as you go down the road. If it's not been done before, all new shoes, springs, and hardware would be a good idea.
 

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Discussion Starter · #4 ·
I've done a quick check of the parking brake cables underneath and they don't appear to be binding. When it happens again, I will check the the cable to see if it's siezed.
 

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...the right rear brake will start to drag slightly. Once it starts dragging, it progressively gets worse and eventually gets hot enough to smoke. The left rear brake doesn't have this problem. After sitting for anywhere from 5 to 15 minutes, the brake will release and I can continue driving. When it releases, I hear clicking sounds from the right rear wheel.
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Any ideas?
The RHR brakes aren't assembled correctly. Click my black Bronco in my sig & find the group of diagrams that deal with drums.
The Brake Warning lamp and ABS Warning lamp light up...
The low-fluid switch in the reservoir is closing. Find out why.
I think my next steps are:
...
Remove, inspect, and clean the RABS valve. This thing is very expensive at the Ford parts house.
Leave it alone.
 

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Discussion Starter · #7 ·
The Solution

I finally found the RABS control module and it reported an error with the RABS valve, so I replaced the valve. The problem did not go away.

It turns out that the brake lines do have a small section of rubber hose near each wheel and these hoses had started to disintegrate inside. The inner wall of the right rear hose must have worn out in such a way to allow brake fluid easily to the cylinder, but not allow the fluid to flow as easily back out of the cylinder. When I replace the rubber brake hoses, the problem went away.
 

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Bringing this post back, hopefully someone can shed some light on a similar issue:
1992 bronco, 5.0, auto. 150k.
Been having this issue for a while now and can't figure it out. When driving regularly and come to a stop sign and start to accelerate again it feels like the rear brakes are binding up. They also lock up prematurely at times. Yesterday I pulled the drums expecting to see worn shoes and broken springs but the brakes looked perfect and everything looked fairly new. There was no oil or brake fluid leaking from anywhere. Could this be a rear wheel bearing going bad. There are no other noises except a medium pitch squeak at less than 1 mph.

What are the symptoms of a bad rear wheel bearing?
How do I check if they are bad?
Can this be a brake issue?
What should I check?
 

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Discussion Starter · #9 ·
Can you tell if it's just one side or both? What do you do when the brakes lock up?

When this happened to mine it was only one side. I would have to pull over and just wait. About 10 minutes later I would hear a clunk from the right side when the brake released and I could easily drive away. (If I kept driving very long, though, the problem reappeared quickly.)

Definitely check the rubber brake hoses towards the back near each wheel. That was the problem with mine. The interior of the hose had detiorated and, when the fluid was hot, would behave like a one-way valve keeping brake fluid in the drum actuating the shoes. An easy fix.
 

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1992 bronco, 5.0, auto. 150k.
That's a start... How about putting ALL the details in your profile & signature? Trans model, t-case shifter, tire size, trim level, options, miles, mods, maintenance, repairs, damage...
...start to accelerate again it feels like the rear brakes are binding up. They also lock up prematurely at times.
Do you ever use the e-brake? Does it have the lock-in wedge recall?
Could this be a rear wheel bearing going bad.
Not likely.
What are the symptoms of a bad rear wheel bearing?
Roar or rumble while driving, and diff. oil on the brakes.
How do I check if they are bad?
Chock the front wheels, jack up a rear (e-brake fully released), and see how far the tire can be moved up/down/fore/aft.
Can this be a brake issue?
Of course.
What should I check?
Trans, t-case, driveshaft, diff, ALL brakes/booster/MC/e-brake cables, RABS valve, alignment...
 

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Thanks for the input guys. It feels like both wheels are hanging up. So today is the first day driving the truck again after having the drums off and inspecting. The issue has seemed to go away for the most part but it did happen once. Before having the drums off the brakes hung up each time I stepped on the brakes. The brakes aren't locking up anymore except for one time. This time I heard a slight clunk when it released. I'll check that rear hose tomorrow to see if it's old looking. That will be the first thing I replace. Everything else visually looks to be in good shape.

E4OD, NP205 push button, XLT all stock.
 

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Posting that info is nearly worthless. Put it in your profile & signature so it automatically appears with each of your posts. That way, we don't have to keep asking, or go digging back thru your posts to find it.
 
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