Touchy rear brakes, locking up

[great white]

Pop the wheels off and the drums will slide off the studs on that 10 bolt rear easily after a turn or two of the adjusters.

Then you can see if it's oil contamination or not. It will be obvious if there is contamination inside the drum. There should be nothing that looks like oil or dark brake dust. That's the great thing about drum brakes: the brake dust makes it easy to trace where oil contamination comes from.

The axle seals will start at the axle., the wheel cylinder.....well, you see where I'm going.

Until you pull 'em, you're just guessing at the problem.

You need to troubleshoot, not guess.

 

[454cid]

Pop the wheels off and the drums will slide off the studs on that 10 bolt rear

Who are you talking to? Neither the OP or I have a 10-bolt.

 

[Jorge6.5]

Yeah I was waiting to get some time to pull the drums off, they are easy to remove. By the way, I'm running a 14 bolt semi floater.

Figured I would get some suggestions before I do any work. Thanks

 

[great white]

Yeah I was waiting to get some time to pull the drums off, they are easy to remove. By the way, I'm running a 14 bolt semi floater.

Figured I would get some suggestions before I do any work. Thanks

Just as easy to pop those off as a 10 bolt.

 

[t93k2500]

Every GM vehicle ive ever driven with rear drums are sensitive when wet. Issue quickly goes away after initial application though.

 

[98_k1500]

This issue is usually caused by excessive brake dust build up inside the drums. It can typically be resolved by removing the drums and giving everything inside them a good washing with brake cleaner. I have seen this resolve the problem many times, especially if the problem is notably worse when the humidity is high outside.

 

[shortchevy]

Could this possibly be a Hardware issue? springs do get weak over time... If they dont have the strength to pull the pads back and collapse the wheel cylinders then would the brakes act like this? My truck does this too, it seems to do it only on the first couple stops of the day. I have had the drums off and everything looks fine. No leaks of any kind.

 

[454cid]

Could this possibly be a Hardware issue? springs do get weak over time...

I intend to find out when it gets warm. I actually bought hardware awhile back when Rockauto had a clearance sale on it. I also picked up to AC Delco cylinders...... made in China unfortunately. I would still like to get a new parking brake cable, and shoes. Hopefully, the drums are still in good shape. The truck lurches as I stop, and I wonder if the drums are out of round, besides being super grabby when wet.

What's your RPO code for brakes, and do you have slide on/off drums or are they on the back side of your hubs?

 

[Jorge6.5]

I do not know the rpo code, its not the original rear end (came from light duty 3/4) the drums slip right off, it's only a semi floating rear end.

I'm considering to just go ahead and get new shoes, hard ware and having the drums turned. Mileage is unknown because the brakes were on the rear when I got it from the junk yard, I only replaced the wheel cylinders.

 

[IOWNJUNK]

Not original rear? If the slave cylinder is not the same size as the original then the master cylinder/prop valve may be sending too much pressure to the rear brakes, causing them to lock. Big slaves work slower/small work faster.