drum brakes 1970 C10

[Josie]

Hi ETCG

I write too much in my questions so here is my attempt try to make a short one. 😛

I get a brake knocking/ sticking on the Right rear (passenger side) every turn of the wheel for (1 to 4 revolutions) after resuming from a full stop, coasting or with throttle, and only after the brakes are heated up. All 4 wheels are drum brakes.

In the past 1000 Miles I have replaced:

-New lines and hoses on the front from the Proportioning valve to Wheels
-New master cylinder and new fluid
-Bled all 4 brakes myself (and the master first when replaced it)
-Had my local shop check the job (first time I had done brake lines) and the said they rebled. pedal was firmer.

I plan to:

1) Replace both the Wheel cylinders, (1 needs replacing anyway – not leaking now, but will be someday the shop said..its the LEFT rear not the suspect wheel) Bought these already

2) Replace shoes (RIGHT REAR Trailing shoe on the suspect wheel – has a corner cracked off.) Will be buying these

3) Replace rear lines to the Axle T – might do the rubber hose too.

4) I have already swapped sides with the drums to see if the issue followed, its still a knock on the RR. Also turned the adjusters down a bit which helped some. But they are auto adjusters.

5) Brakes were at 70% the shop said and the spring kit is not dirty looks like they were replaced “30%” ago by the old owner when he did the brakes last.

Any idea what would have caused this? It started doing this a few days after the shop bled the system. I checked the master and it was over flowing with fluid at that time. No leaks in the system then or since then. I don’t want whatever has foiled the existing brakes to foil my new parts. Anything else I should look at?(or have close by) before I start the process? If these are anything like the front ones, there will be some time, swearing and getting dirty involved! Don;t want to have to stop and go get parts mid job. 😛

Thanks for all your great help out there 🙂 here are some pics for reference.

Brakes (these are the fronts, back look exact same)

Cylinders…with extra “spidey-sence” 😛

Project out for a ride last month.

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Topic

[college man]

If the brakes heated up They may have been to tight.

[EricTheCarGuy]

I LOVE those old trucks. Before you go replacing everything, check the bosses where the brake shoes ride. I suspect they’ve worn deep grooves that the shoes are getting caught in. This is often the cause of the noise you describe. This video may be helpful for you.

More info on brake problems here.

http://www.ericthecarguy.com/faq/solving-brake-problems

Good luck and keep us posted.

[Josie]

OMG Thank you so much Eric!

This video is so detailed! Has anyone told you how awesome you are today? :cheer: So many thanks!

Sorry this is weeks late. I didn’t see anyone had replied as I usually get an e-mail when someone does. (I’ll check my settings again on the forum)

To your answer. The bosses were also something I heard could be suspect . I tried a dab of white lithium grease on each of them as a test to see if it made a difference, but no big change was found. I didn’t clean them with a wire wheel like you did in the video though so I’ll be sure to clean them and use anti-seize instead when i go to do the shoes and Wheel Cylinders. (I was told the WC’s would need to be done at some point anyway) For now I was anything simple to see if it made a difference. I even adjusted the shoes back some in case they were just too tight. But my auto adjusters work very well so a few feet of reversing in a parking lot and they are back to being snug.

Over all, the sticking (after stop) kept coming back after about 15 min of city driving. I even found driving UP steep hills it would cause it sometimes too hmm..I was stumped. :unsure:

Then I did something else which I think you’d approve of. I put a better set of tires on the back! After having the old ones off one day I noticed they had become deformed, cracked and worn (worse than I thought). These old tires came with the “project” so I’d never experienced any different tires on the truck till now. I am sure there must have been a broken belt on the tread (though no belts were showing) because one portion had a 2 inch square indent and bump. WELL… SUCCESS! B)

I have had the newer tires on for a week and the problem is 99.9 gone!!. :cheer:

I am thinking the tires were not the complete cause though. I bet the extra vibration the old tires caused were vibrating the shoes around during braking and maybe as you say, made them rub against the bosses. The brakes are safe, but they do need to be inspected still, just waiting for a nice day to check them out.

I did buy my new wheel cylinders, new rear lines (pre fabed), have brake fluid, and a set of new shoes (with the rivets LOL) All of that was about $100 but will be worth it. The local garage does turn down services on drums so while I’m at it I’ll get them to check mine are OK and true. (they do look pretty new with lots of life left in them.) The only issue for this repair will be the patience to get the lines off the “T” connect at the back. Fingers crossed! The truck is 46 years old (1970) and I wonder if the lines are too! 🙂

In closing, Just want to say thanks again Eric. I started watching your youtube videos over 3 years ago. I’ll be purchasing one from you soon too when I attempt my first clutch replacement in my 96 GSR. I’ve shared how great a help you’ve been with my Dad (who loves the garage) and Brother (who is also a long time technician) who are both back east and I got them hooked on your videos now too. 🙂 I guess I should say welcome to the family! :cheer:

All best to you and yours Eric (and that goes for you too College Man. You reply to my posts here all the time!) ! Keep up the great work guys I’ll post
pics here of the repair when I get to see some west coast sun again. The Rainy season is upon us.

~GSR

PS: Both cars say thanks guys!

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[Charles]

Just a note about GM sticking bakes. I personally had experience with a 2000 Savana where the rear brakes were sticking and getting hot. Could not for the life of me figure out what I had done wrong (Had just done a brake job). After much toil and nashing of teeth I went to the dealership and purchased OEM shoes for the rear. That was it! I compared the aftermarket shoes to the OEM and there was not visible difference. The only thing I can figure is the metal of the after market shoes was softer and more flexible allowing the self adjusters to over tighten the brakes. No problem since I switches to OEM.

[college man]

I like the fleet you got going. 🙂 Glad things are working out. Thanks for keeping us updated.

[Author]

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