Gonna rebuild the rear drum brakes on my ‘67

[jabborabbo]

Does anyone have a link to a DIY regarding rear drum brake rebuilding for my ‘67 GMC or other compatible year (and/or particular things to watch for?). I rebuilt the front brakes a while back with no problems, but I feel better if I have a reliable go-by handy….

Also, should I rebuild the master brake cylinder while I’m at it or wait until it starts misbehaving?

Thanks in advance for any and all info! I love this board!!!

[1970cstblazer]

Make sure you do only one side at a time. That way you can get an idea of how to reassemble if you are uncertain, or take a pic of it prior to disassembly. Make sure the shoe with the shorter lining material goes towards the front. Always preferably replace or rebuild the wheel cylinders, since they fail if they set just a few months, and ensure the bleeder screw can loosen. Make sure the self adjuster is free and apply some high temp anti-seize to the threads. Use high temp anti-seize on the drum to hub mating surfaces to ensure the drum comes off the next time you need to service the brakes. When you have the shoes adjusted properly on both LH and RH, adjust the parking brake.

[dmjlambert]

1970cstblazer packed a lot of great info in that post. Since you did the front without problems you will probably be fine at the rear.

Another guide is the service manual. If you don't have a paper one, they are fairly inexpensive, I bought a used one from eBay. Forum member hatzie uploaded PDF manuals here: https://67-72chevytrucks.com/vboard/...d.php?t=558016

One thing I wish I was aware of when I did mine is when you go to the parts store to get a brake job kit, which has various springs and doodads in it, the self-adjusters and associated parts are not in that kit, and there is a separate kit available having that stuff in it. The star wheel adjuster may or may not be included in such a kit, but a replacement should be available.

If your rubber hoses are old, this would be a good time to replace them. Attempting to remove the hose from the hard line or disconnecting the hard line from a wheel cylinder may result in destruction of the hard line because of the tendency of 50 years of rust to seize the threads. If you run into that situation don't worry too much because Inline Tube has the pre-bent hard lines. I recommend their plain steel lines, not stainless steel.

When you bleed the brakes, put a little chapstick on the bleeder screw threads and re-insert them, and attach clear vinyl hoses onto the bleeders that is long enough for the ends to remain submerged in a small can or bottle that has an inch or so of brake fluid. I use a small used spice bottle sitting in a coffee can (because the spice bottle fills up quickly, and I have also used the one-man bleeder kits available at the parts store. Then you can bleed your brakes the one-man method. Press and release the brake pedal repeatedly and slowly, stopping each depression when the brake pedal is still a couple inches off the firewall. Bleed until the brake fluid coming out of the bleeder screws is nice and clean and new looking. Top off the fluid level in the main cylinder often during the process. If the main cylinder fluid looks old and dirty, start by removing most of the fluid in the main cylinder reservoir first and fill it up with new fluid, and then bleed liberally, such as using a quart of fluid through the bleeding process so you get all the old dirty fluid out of the system, and bleed/flush the front brake lines, too.

Regarding the parking brakes, while you have the brakes apart, make sure your parking brake cable glides through its conduit in both directions smoothly and the spring that is wrapped around the cable inside the brake assembly is in good condition. I had both seized up and had to replace the conduit and cable assembly. I tip I received here on the forum about how to release the little fingers that hold the conduit to the backing plate is compress the fingers with a tiny hose clamp.

Ask questions here if you get stumped on anything.

[dmb]

you may have trouble finding rear drums

[oneshotkyle]

Originally Posted by dmb

you may have trouble finding rear drums

I bought drums at orielly auto parts. My truck didnt have adjuster hole in backing plate so i drilled the new drums

[dagnabbitt]

Originally Posted by 1970cstblazer

Make sure you do only one side at a time. That way you can get an idea of how to reassemble if you are uncertain, or take a pic of it prior to disassembly..

Great advice

[jabborabbo]

Excellent comments and advice! I really appreciate them! I don’t think this truck has ever had a rear brake job…. I’m gonna change that!

Any other advice regarding the master cylinder?

[dmjlambert]

I'm not the expert on master cylinders, but I would tend to replace it with a new one only if after bleeding pedal slowly sinks to the floor when you hold the pedal down or if you get some other malfunction. Use the parts store brand that has lifetime warranty. Take your old one to the parts store to compare and make sure you're getting the right one.

[michael bustamante]

Don't lose that parking brake horn in the inside. It's a one year only I got i found out. Also, if you got you cell phone, take pics as you're taking it down for reference as well

[jabborabbo]

Originally Posted by michael bustamante

Don't lose that parking brake horn in the inside. It's a one year only I got i found out. Also, if you got you cell phone, take pics as you're taking it down for reference as well

Thanks! Can you post a picture or refer me to the manual that shows/discusses that horn?

[70STOVEBOLT]

Parking brake horn? What is that?

[A1971Blazer]

Here's a nice exploded view of all the drum brake components

[jabborabbo]

I kinda think I need to replace this rear brake cylinder…what say ye? (Actually I’m gonna replace both of them 😀 ). Kinda scary….

[70STOVEBOLT]

Yes replace them both, they are not expensive.

[oneshotkyle]

Replace it all nothing too expensive

[dmb]

Originally Posted by oneshotkyle

I bought drums at orielly auto parts. My truck didnt have adjuster hole in backing plate so i drilled the new drums

I had a 67 GMC 1/2 ton I could not get rear drums for, but that was a few years ago

[oneshotkyle]

Originally Posted by dmb

I had a 67 GMC 1/2 ton I could not get rear drums for, but that was a few years ago

Available on the west

[Rust_never_sleeps]

my 70 didn't have adjuster holes in the drums so the previous owner cut some.
Looks like they used a guide dog and a .410 shotgun to do it ;-)

[67C10Step]

I completely rebuilt the rear brakes on my 67 a few years ago and found out the strut spring is not included in any kit out there. Took a few tries but with the help of a great guy at my local O'Reily's I found the part number for it. If you need those, let me know and I will try to look that number up for you. They actually had them in stock.

[jabborabbo]

Okay…there’s this assembly that attaches to the brake backing plate that’s related to the parking brake - I’m showing a crappy out-of-focus close-up photo and a not-so-close up in-focus photo…my question: where in Hades is that assembly shown in any of the manuals for my ‘67? I haven’t completely cleaned it, but it looks like there’s a fiber or felt or whatever piece or gasket or whatever in there….

Help!!!!

[michael bustamante]

Originally Posted by 70STOVEBOLT

Parking brake horn? What is that?

Lol. I have no idea what it's really called. The e brake cable attaches to it and spreads the shoes to the drum
The s-a arm in the diagram above

[franken]

Once a brake job was easy.