Rear Drums Locking Up

I have a 2005 DCSB 4x4 with 90k on the clock. So I posted a while back that my brakes would lock up either taking off or at low speed. Pretty certain i have isolated it to being my rear left drum (At rest i touched front rotors and rear drums. Left drum was more hot than the others)

I just had a tire shop put on new tires. When i picked up the truck the mechanic mentioned that my front brakes were at 30% rears drums 70%. I researched this issue and it seems that trucks closer to 100k have developed a channel that the rear shoes like to "ride" in. Seeing as the mechanic had to take off the drum case to see how much shoe i had left, could that have led to this intermittent sudden braking issue

 

I'm assuming your concern is that after the tech opened the rear drums, now the shoes are not riding in that channel anymore?

That doesn't seem like it's the way it's supposed to be, but it's possible.

My 2007 would have an issue every so often where the breaks would lock up, but it was due to rust (happened mostly after a wash/rain).

Fink

 

x2 on the lock up after a rain or wash...

Mine sometimes does this afterwards and when I go into reverse I just have to push the gas pedal down a bit and it frees up.