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Old 05-01-2019, 08:47 AM   #1
Markuli
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Rear drum locks up going forward, frees up in reverse.

I'm posting this in an attempt to save a fellow C10'er some headache.

I've been fighting with this phenomena for the past two weeks, ever since I replaced the drums and shoes on all four corners of my '67 1/2 ton (and swapped out wheel cylinders in the rear). Even with my adjustment star fully bottomed out, my drums would always have some friction on the driver's side rear wheel before I even set it back down on the ground.

When I would go drive after assembling the system, the truck would brake okay and I'd be able to drive around and adjust the shoes. But after I finished and I'd let it sit overnight, the right rear drum would, without fail, hang up and drag hard when I tried to move forward.

I took apart and reassembled/ inspected the whole shoe assembly three times over before I realized that my brake shoes would never really touch the upper pivot point at the top, which was odd because the passenger's side shoes contacted it just fine.

It turns out that the parking brake cable was frozen in place, which pushed out against the new shoes. This wasn't an issue with the old, worn out drums and shoes because they were much further spread- out within the assembly to make up for the lack of material. Now with new pads and full- thickness drums, the parking brake became a problem and limited how tight the pads could get to the pivot.

For the moment, I've just disconnected the parking brake lever from the cable itself so I still have use of it on the passenger's side. Today I'll head home and take the truck for a spin to see if it is finally freed up driving forwards, now that it's sat overnight, and that should confirm my suspicions.

So for anyone reading this post, if you're experiencing the same bizarre brake problems as me, check your parking brake and either adjust or replace your linkage.
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Old 05-03-2019, 11:47 PM   #2
Overdriven
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Re: Rear drum locks up going forward, frees up in reverse.

Double check that you have the brake shoes oriented properly. There is a leading shoe and a trailing shoe, they are only slightly different. Sorry I don’t recall which is leading and which is trailing but that info should be easy to find. I made this mistake once and couldn’t get the brakes to adjust right, they dragged with no adjustment and they’d lock up way too easily. After chasing my tail for a week I had my mechanic take a look and he pointed out my mistake as soon as he pulled the drum. Had him swap the shoes around since it was there and the brakes work as they should.

Edit: When inspecting the shoes be aware you may have both leading shoes on one side and both trailing on the other. Or you could just have trailing and leading reversed on each side.

Last edited by Overdriven; 05-04-2019 at 02:22 AM.
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Old 05-07-2019, 03:34 PM   #3
kwmech
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Re: Rear drum locks up going forward, frees up in reverse.

The longer/larger shoe always goes towards the rear of the truck
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Old 05-07-2019, 06:52 PM   #4
Markuli
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Re: Rear drum locks up going forward, frees up in reverse.

I learned that when I first changed out all my hardware- the drums wouldn't even go on at that point! So I know everything is oriented properly. I'm just about positive the e-brake cable was slightly engaged and rusted solid in that position, so it ever so slightly pushed out my shoes. Now that it's disconnected my truck rolls just fine, forwards and backwards.
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