76 midget rear brake lock up

[Tipsy]

Recently I replaced my master cylinder (bench bled), put speedbleeders on all four wheels, rebuilt the brake pressure warning valve and bled the entire system several times just to be sure it was all clear and working properly. It's been fine for over a month now. I only drive it around town and mostly on weekends. Today after a trip to a local hardware store when it ran fine the entire time I set off on another trip to the same store. I got as far as the stop sign at the corner, applied the brakes to slow down and then as I let off, the brakes at just the rear or just the drivers side rear locked up and I skidded to a dead stop! I tried to inch forward but it was still locked up. So I backed up towards the curb to park and walk back home and it released. So I turned around and drove home. I just checked all systems, fluid is fine, no leaks in brake lines, no visible leakage around rear wheels. I will remove rear wheels tomorrow and see how it looks inside the drum. In the meantime, anyone ever have this happen to them? Should I be thinking new rear wheel cylinders? Thanks for any advice!
Jeff

 

[aeronca65t]

May be adjusted too tight.
As brakes are applied, the shoes rotate slightly and moves more "out" against the drum (due to a cam effect in the design). If they are too tight they cannot rotate "back" when brakes are released.

Could also be single rear hydraulic flex line (near "tee" to each rear brake). Sometimes they collapse internally and act as a one-way check valve, holding hydraulic pressure on. I've seen this a number of times.

 

[Tipsy]

Thanks for the reply! I'll check how tight they are. I adjusted them a long time ago, if anything I would think at this point they would be worn to the point that they might need to be adjusted again. But maybe the new master cylinder has changed the whole dynamic. It wasn't working the rear brakes much anyway and thats one of the reasons I put in the new master. I suppose I will replace that rear flex line too just to be safe.
Thanks Again!
Jeff

 

[Tipsy]

I discovered that my drivers side rear wheel brake cylinder is leaking. Should I replace both of them or does the "if it ain't broke don't fix it rule apply here? I'm thinking do both because I gotta bleed it anyway? What do you think?
actually I'm thinking re-do the whole kit because this sides got some fluid leakage onto the pads so they need to be replaced. VB has a kit for rear drums on a 1500 that includes everything for under $100. Sounds like the way to go.?
Thanks!
Jeff