Slow speed locking

[subastew]

TL;DR - Brakes are "locking" when slowing to a stop, help me.



As this is my first post, I'd like to apologize for coming straight here to ask a few simple questions; I admit I registered to finally get a straight answer on this, as this forum seems to be the best source for knowledge and help.

We'll start off about one month ago on a trip to pick up a dresser in my wife's 99 Ford Ranger, regular cab short bed, 4x4. I parked it on an inclined driveway and engaged the parking brake. After loading up, disengaging the brake and driving off we got about 100 feet before it stopped moving (this was a slowly advancing stop, not abrupt). Reverse worked fine, but it wouldn't go forward. We took it to a garage not far from the house and they pulled the drums, cleaned and adjusted the brakes and springs, put it all back together and said we'd need new e-brake cables. Now, when slowing to a stop, the brakes jerk and try to lock up. This doesn't happen all the time (especially after taking the drums off and cleaning them).

Here is what I think I know, based on the research I've done:

The front rotors are warped, as there is catching when slowly coming to a stop, that familiar back and forth.

The drums in the rear are no longer circular, and this is causing the jerking/locking.

The hoses coming to each caliper/drum are a little clogged.

The pistons in the front calipers aren't returning to open position, because it feels like I have 500lbs of crap in the bed when I don't.

My question is, in what order do I investigate the problem? I don't want to replace lines if the proportioning valve is toast, and I don't want to resurface the drums if I need new calipers. Has anyone else had the locking issue?

 

[letsfightrob]

Mine actually does this too me in the morning first couple times I use the brakes. My e-brake is disconnected. 2000 4.0l 2wd. I believe its the fluid. Try bleeding and seeing?

 

[Bronco638]

I'm having a hard time figuring out what you mean by "here's what I think I know". Do you know these listed items as fact or possibilities, based on research (it would appear to be the latter). It would help to verify everything in that list.

So, the front wheels rotate freely but the rear wheels do not?

If so, it sounds like the e-brake cables my not be releasing completely (or at all).

If you are able to verify everything in the list, it sounds more like the brake system needs a complete overhaul.

How many miles on the truck and what's its overall condition?

 

[adsm08]

Drive truck 2 miles. Touch all four wheels. When you find the brake that is locked up you will know it.

Then take that wheel off and check the brakes. If it's a front wheel try compressing the caliper, two large C clamps can be used to push the pistons in. If the caliper won't compress open the bleeder screw a bit and try again. If it still won't go you need a caliper, if it works easily with the bleeder open the hose is clogged. Also be sure to check the slide pins and make sure the pads aren't just stuck in the bracket.


If a rear wheel is the culprit remove the drum and have someone work the parking brake to see if it is moving, particularly to see if it is releasing.

At this point it is almost certain that the affected hard part (the drum or the rotor) is warped and will need resurfaced. You will likely also want to replace the friction material as that level of heat is bad for the brake material.



One other thing, after an issue like this it is highly recommended to get the brake fluid flushed out. Being exposed to extreme heat like that degrades the fluid and makes it less able to withstand normal operating temperatures in the brake system.

Another quick test for which axle has warped brakes, 55 mph, let go of the wheel and lightly apply the brakes. If the steering wheel shakes it's in the front. If it doesn't it's in the rear.