Brake drum problems

[808_67C10]

I swear, one of these days I will start a build thread.

So here is my problem, I have an 85 2wd C10 with rear drums. I got new rims and took off my old ones to paint the drums and front calipers.

I took the drums off, hit um with a wire brush, a few coats of paint (only on the outside ... in case someone felt the urge to ask) and slid them back on. Shoes had plenty left on them so, no need to change. Then I put my wheels back on and fired her up to spin the truck around in the garage and the back lock up when I hit the brake pedal. I can drive up and down the driveway fine with no apparent drag but, when I touch the pedal, BOTH rears lock up.

When I let off the brake pedal, they release fine. Pedal has good pressure just like before I started.

Even when I roll forward a little bit in Drive and tap the brake, they lock but as soon as I let off the pedal, they release and the truck continues forward.

I dont get it... brakes were perfectly fine before I started and I didn't change anything in the rear.

Any ideas?

[Dead Parrot]

Some possibilities: overspray paint lightly coated either/and insides of drum and shoes. Other contamination did same. You swapped the left and right drums and the drum wear groves and such now no longer match the shoes.

[808_67C10]

Originally Posted by Dead Parrot

Some possibilities: overspray paint lightly coated either/and insides of drum and shoes. Other contamination did same. You swapped the left and right drums and the drum wear groves and such now no longer match the shoes.

I was very careful not to get paint inside the drums... but, I will pull them apart and check... a lil over spray may be a possibility. Didn't really look inside after I sprayed them. I did one side at a time so, no possibility of a swap.

[sweetk30]

some times my old 1ton will get rear grabby the first few hits when there is a huge moisture level swing from lots of rain or snow . does it more when i dont drive it every day .

good blast up the road and feather them in burns the moisture out .

[808_67C10]

Originally Posted by sweetk30

some times my old 1ton will get rear grabby the first few hits when there is a huge moisture level swing from lots of rain or snow . does it more when i dont drive it every day .

good blast up the road and feather them in burns the moisture out .

Thanks... This isnt a random issue... its every time i touch the brake since I pulled the drums off and put it back together. It isnt safe to drive so, havent tried to get um warm and see if its different.

I am going to pull it apart tonight to see more.

[D13]

The pads ride on little bumps in the backing plates, and their 'tightness' is controlled by the adjuster.

Most likely what happened is the drums are a little sloppy on the center hub and when you installed them they shifted. Pull the wheels and put the drums on with 2 lugs finger tignt and spin them. If there is a tight spot turn it to that point, then pull the lugs off and install the wheel. The drums should recenter and be better. Alternatively put on the wheel just finger tight, so the drum can still move, then spin it around slowly until the tight spot is lessened. Then tighten the wheels.

If that doesn't fix it you'll have to go back in. First, note which way the adjuster star wheel needs to move to allow the shoes to move closer together at the boot. Lift the adjuster tab off the star wheel and back the star wheel off 3-4 teeth.

Second, look at the bumps the shoes ride on and see if they are flat, if not, a light filing is in order. They tend to get a notch worn in them and the shoes can grab ther. The service manual cauls for a tiny dab of grease, I usually use just enough to leave a film so the bumps don't rust.

[808_67C10]

Originally Posted by D13

The pads ride on little bumps in the backing plates, and their 'tightness' is controlled by the adjuster.

Most likely what happened is the drums are a little sloppy on the center hub and when you installed them they shifted. Pull the wheels and put the drums on with 2 lugs finger tignt and spin them. If there is a tight spot turn it to that point, then pull the lugs off and install the wheel. The drums should recenter and be better. Alternatively put on the wheel just finger tight, so the drum can still move, then spin it around slowly until the tight spot is lessened. Then tighten the wheels.

If that doesn't fix it you'll have to go back in. First, note which way the adjuster star wheel needs to move to allow the shoes to move closer together at the boot. Lift the adjuster tab off the star wheel and back the star wheel off 3-4 teeth.

Second, look at the bumps the shoes ride on and see if they are flat, if not, a light filing is in order. They tend to get a notch worn in them and the shoes can grab ther. The service manual cauls for a tiny dab of grease, I usually use just enough to leave a film so the bumps don't rust.

Awesome advice... thank you. I will let you all know how it goes when I go back in to inspect tonight. I just think its odd, I never touched anything. I can see the shoes shifting when I put the drum back on though. Regardless, she will be back on jack stands tonight.

[808_67C10]

Pulled the wheels, tried to reseat the shoes, cycled the e brake a few times, even tried to swap the drums to see if it was a warped or cracked drum. Also, I took some 220 grit to the shoes and drum to make sure there wasnt any overspray causing the problem.

When I spin the rear I can feel it grabbing in one spot on the drivers side. I tried to tighten the star adjuster to bring the shoes together and was able to get it so the wheels spun freely, then set it down and drove in reverse and forward... the problem is still there. Its only really bad when I go forward, they dont lock when I am backing up and hit the brakes. No grooves on the 6 pads that the shoes ride on either.

This is driving me crazy. Should I yank it all apart and replace the shoes n brake hardware? I hate just replacing things till I find the problem...

[chrismoore701]

Did you take them apart in any way? The shoes? Sounds like your emregency brake bar is out of wack. Take that off and put things back together and see if that helps. it is the bar that runs across from shoe to shoe on the top half of the assembly with a spring on one side. Check that out. May just need to go through the brakes and rebuild them.

Good luck
Chris

[808_67C10]

Originally Posted by D13

The pads ride on little bumps in the backing plates, and their 'tightness' is controlled by the adjuster.

Most likely what happened is the drums are a little sloppy on the center hub and when you installed them they shifted. Pull the wheels and put the drums on with 2 lugs finger tignt and spin them. If there is a tight spot turn it to that point, then pull the lugs off and install the wheel. The drums should recenter and be better. Alternatively put on the wheel just finger tight, so the drum can still move, then spin it around slowly until the tight spot is lessened. Then tighten the wheels.

If that doesn't fix it you'll have to go back in. First, note which way the adjuster star wheel needs to move to allow the shoes to move closer together at the boot. Lift the adjuster tab off the star wheel and back the star wheel off 3-4 teeth.

Second, look at the bumps the shoes ride on and see if they are flat, if not, a light filing is in order. They tend to get a notch worn in them and the shoes can grab ther. The service manual cauls for a tiny dab of grease, I usually use just enough to leave a film so the bumps don't rust.

After pulling it apart again this morning and putting some emphasis on where the shoes ride, D13 - you nailed it!!! As you can see in the pic, the backing plate pads were severely gouged. I didnt notice it last night (lighting in my garage sucks) but, when I took a quick file to it, it showed how deep they actually were. I filed down all the pads on both sides, put a light coat of grease over the spots, and slid the drums back. Works like a champ now!!! Hell of a lesson learned. In all my years of working on old school cars n trucks, this is a first for me. Thank you D13! I would never have thought that could cause the issue that it did.

[D13]

Glad to help. I think of it as a return in kind of all the good help I have recieved here.

And thank you for posting what fixed it. Now the next person who has this kind of issue can find a solutions.