Rear brakes lock up when cold only

[dvdswan]

As stated, when the vehicle sits for a while (overnight or long enough to cool the shoes down to ambient temperature) and moving under 20 mph I start to apply the brakes and the rear locks up. After warming up they will not lock up no matter how hard you try. I haven't pull the drums off yet because I don't think the wheel cylinders are leaking as this only occurs when cold.

Any ideas?

 

[Dirtman]

The drums are flash rusting. I had a few vehicles do it. After it rains or is cold/humid I would just set the parking brake lightly and drive slow for a few hundred feet and it would clean the rust off then they would work normally.

Cheap metallic shoes, cheap drums, or too much brake dust in the drum will cause this. It's not necessarily a symptom of a major problem (it can be) but usually it just means time to clean everything and put some better shoes on it.

 

[dvdswan]

Thank you @Dirtman my guess would be the cheap shoes. I'll dig into it this weekend. Glad its not serious.

 

[Uncle Gump]

These trucks are known for this...

Something I've found that works for me is to keep the rear brakes adjusted favoring the tighter side. My theory has to do with the way brake fluid is applied to both rear shoes evenly on both shoes until they self energize. When they do... the fluid on the rear brake shoe is displaced onto the front shoe... and the brakes lock up. So a tighter brake shoe adjustment means less fluid transferred.

There is also an old TSB about sealing up all water intrusion on the backing plates.

 

[Dirtman]

These trucks are known for this...

Something I've found that works for me is to keep the rear brakes adjusted favoring the tighter side. My theory has to do with the way brake fluid is applied to both rear shoes evenly on both shoes until they self energize. When they do... the fluid on the rear brake shoe is displaced onto the front shoe... and the brakes lock up. So a tighter brake shoe adjustment means less fluid transferred.

There is also an old TSB about sealing up all water intrusion on the backing plates.

The water intrusion thing has always confused me. Drums can never be 100% sealed, its impossible. So water is unavoidable sometimes, the more you seal them the less water drains out. Plus this particular issue happens even when driving dry and you park it but it gets really humid. So intrusion wasn't an issue, damp air is always getting in. I'm not arguing with you, arguing about the theory. Cause ford may have TSB'S but ive had it happen on a chevy and a dodge.

 

[19Walt93]

The TSB was quite a few years ago. I sealed the backing plates on my new 04 when I did the PDI and never had a grabbing problem. I didn't have much confidence that it would work but it took a few minutes and a few dabs of silicone sealer. Try it before doing anything expensive, if it works you won.

 

[Uncle Gump]

Adjusting your brakes is absolutely free... you don't even have to get out of the drivers seat to do it either. If everything works properly.

 

[55trucker]

wild thought........both? of your axles seals are leaking?

 

[dvdswan]

wild thought........both? of your axles seals are leaking?

This is not the case, as if it were, then the brakes would lock all the time, hot or cold.

 

[Bgunner]

This is not the case, as if it were, then the brakes would lock all the time, hot or cold.

Not necessarily, Both my wheel cylinders were leaking and when cold, or sat for a long time they would lock up, usually just one, but when hot they would only lock up if I spiked the brakes hard. Now that they are both replaced the rears only lock up if I spike the brakes hard, my RABS does not work so they will lock up.

 

[Dirtman]

Adjusting your brakes is absolutely free... you don't even have to get out of the drivers seat to do it either. If everything works properly.

Might as well play the lottery if that works.

 

[rubydist]

This is exactly why I replace those ancient drum brakes with disc brakes on the trucks I have.

 

[19Walt93]

This is exactly why I replace those ancient drum brakes with disc brakes on the trucks I have.

I hate rear disc brakes, if you're braking hard enough to get any benefit from them all the weight is thrown onto the front wheels. Every spring for 7 years I took the drums off my 2004 Ranger to inspect the brakes, dumped out the dust and put them back on. Every spring for 8 years I completely disassembled the rear disc brakes on my 2011 Ranger, ground the rust off the edges of the rotors, caliper anchors, and slides, lubed all the slide points and put it back together. I forgot to mention grinding the rust and lubing the parking brake mechanism, too.

 

[Mike Tonon]

Mine were locking up when the truck was parked for more than a couple hours in wet conditions. I couldn’t get the shoes to release the drums. I ended up bending the pins on the backing plates and didn’t know it until a few years later.

 

[Zmans]

So, I have 9in rear drums... replaced all the hardware and shoes. Self adjuster operational... lubricant on contact points of the plate, I still have dragging issues after releasing the parking brake. My theory that the cable binds up might prove true.