Brake trouble!!
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Brake trouble!!
I am new here, and need help. I have a 1997 F250 light duty. The problem is the rear brakes. I put the truck in drive and move about 5 feet and the rear brakes engage without even touching the pedal. The truck will move in reverse without any problems. The ABS light is on on the dash, but has been for a long time before this happened. If the light does have anything to do with it. What is the reason for the light being on? I would like to fix the light then go from there.
Thanks
Thanks
Elder User
Joined: Oct 2001
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From: Jersey Shore Not Seaside!
There can be a whole litany of items that can cause a '97 rear drum vehicle to lock up the rear brakes. But we can start with the yellow ABS light.
The two more common reasons for the warning to turn on is that there is not a proper signal from the rear differential speed sensor, the cheapest and easiest repair. The next is a the ABS control valve which should be on the frame rail under the drivers area. On older trucks these usually look like a clump of rust. If the valve is malfunctioning it can lock up the rear brakes by keeping fluid trapped to them.
But the list of potential reasons can include:
Frozen parking brake cables.
Rusted wheel cylinders.
Damaged brake hose from frame to axle acting like a one way valve.
The reason a duo-servo drum brake like what you have only locking in forward motion is due to the design of the brake, and having the primary shoe acting against the secondary shoe forcing it into the drum with more force then the wheel cylinder pressure only. If the primary shoe never retracts the brake force will be much higher in forward then reverse.
The two more common reasons for the warning to turn on is that there is not a proper signal from the rear differential speed sensor, the cheapest and easiest repair. The next is a the ABS control valve which should be on the frame rail under the drivers area. On older trucks these usually look like a clump of rust. If the valve is malfunctioning it can lock up the rear brakes by keeping fluid trapped to them.
But the list of potential reasons can include:
Frozen parking brake cables.
Rusted wheel cylinders.
Damaged brake hose from frame to axle acting like a one way valve.
The reason a duo-servo drum brake like what you have only locking in forward motion is due to the design of the brake, and having the primary shoe acting against the secondary shoe forcing it into the drum with more force then the wheel cylinder pressure only. If the primary shoe never retracts the brake force will be much higher in forward then reverse.
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Thanks for the information. I am going to go ahead and do the rear diff sensor and new shoes, hardware, and wheel cylinders. And whatever else i may find underneath when im there. I will let you know how it turns out. Thanks again
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Well I got everything apart yesterday. Turns out that both adjusters were all screwed up and the wheel cylinder on the pass side wasnt setting in the front shoe. So now I am waiting on my wheel cylinders to come in, no one in town had them in stock. And for some unknown reason the wire going to the speed sensor has been cut by previous owner. So i got that hooked back up. I will let you know how it goes when the wheel cylinders come in and it is all back together.
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