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08-21-2024, 12:41 AM | #1 |
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65 Chevy C10 rear drum brake woes. please help.
Hey fellas, i rebuilt my 65 c10 and put disc brakes up front. i planned to keep the drum brakes in the rear so i ordered a rebuild kit. I couldnt get the rear brakes to work after the rebuild.
Since i put in all new brake lines, hydrobooster and master cylinder i decided it must just have air trapped in them. so i bled them by pumping the brake. still nothing.... bought a vaccume hand pump, and tried bleeding them like that. still nothing. Thought "Maybe the drums are really glazed?" so i used a die grinder with a flapper wheel to sand the inside of the drum. still nothing. bought an AC 110v vaccume pump and pulled a monster vaccume on the master cylinder... still nothing. I figured "maybe i collapsed the original 65 rubber hose from the frame to the rear axle" so i bought a new one. still nothing. So i bought a pressure bleeder. and forced 40psi of brake fluid through the system, bleeding over a litre through the rears. Still.... Nothing. I adjusted the adjuster through the slot in the drum each time. expanding it till it dragged hard and i cant get so much as a change in resistance with the brake. i swapped the wheel cylinders to another set... Still Nothing... What is going on here? did i rebuild the brakes with the wrong kit? is there a oddball drum or something? I looked for new drums, but couldnt find any with the slot in the front for getting to the tensioner/adjuster. i don't have a hole in the backing plate... i am really close to just buying a CPP rear disc brake kit, but i couldnt run 15 inch wheels then. If anyone has an idea, throught or suggestion please let me know. i am at my ends wit here... Last edited by Gumby83; 08-21-2024 at 12:51 AM. |
08-21-2024, 02:36 AM | #2 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
I had the same problem with my '62, the previous owner had installed a master brake cylinder from the Corvette, which is for 4 disc brakes,
the residual pressure valve for the drums was missing, so the drums are not preloaded, I solved my problem with a new master brake cylinder for disc/drums, the residual pressure valves are available separately, so that it can be used in the rear circuit. Was the bench bleeding carried out properly? If the rear circuit does not work at all, even after repeated pumping, although it has been properly bled, then your new master brake cylinder is already broken.
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------------------------------------------- Greetings Harald My 62 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=829782 |
08-21-2024, 03:16 AM | #3 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
Did you "lock out" the proportioning valve when bleeding the brakes? Others on here can explain this better but, I used a cheap special made tool to bleed mine. It goes where the brake warning light would connect to the valve. Otherwise, I think the shuttle closes off the perceived failed half of the system. It looks like the one in the picture.
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08-21-2024, 04:16 AM | #4 | |
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Re: 65 Chevy C10 rear drum brake woes. please help.
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08-21-2024, 11:39 AM | #5 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
I read everything you did again. If you are getting fluid coming out the wheel cylinders when you bleed them then, I'm unsure what could be happening. When I replaced the wheel cylinders on my 66 I bought the Delco replacement. I do have disk/drum. If you have a helper available, maybe remove one of the drums and have your helper push the brake pedal a small amount to see if you have movement. Not enough to pop the cylinders apart but just to see them move. If they don't move then check your master and proportioning valve. I can see why you are stumped.
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08-21-2024, 02:29 PM | #6 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
appreciate the help, i am going to order new drums and see if that fixes the issue.
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08-21-2024, 06:03 PM | #7 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
New drums won’t help.
Do the front brakes work? Can you lock up the wheels? From your description you have plenty of liquid. You don’t have enough pressure though. What’s the size of your master cylinders bore? |
08-21-2024, 06:23 PM | #8 | |
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Re: 65 Chevy C10 rear drum brake woes. please help.
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08-21-2024, 07:15 PM | #9 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
Possibly the pull to one side could also be from not enough pressure.
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08-21-2024, 07:31 PM | #10 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
I agree with geezer99. It is such a simple hydraulic system. I was thinking about the master cylinder. Did your rear brakes work before you changed it? If so, are you sure that the push rod is sitting correctly in the cylinder? I know that some look alike but that there are different types where the pushrod goes. One takes a short rod and the other one takes either a spacer or longer push rod. I had accidentally bought the wrong one once and had a similar problem. Doesn't move far enough to produce pressure. Otherwise I can't think of what would cause the issue. In my opinion, the only thing to do is start troubleshooting at the front and go to the back.
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08-21-2024, 07:47 PM | #11 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
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08-21-2024, 07:50 PM | #12 | |
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Re: 65 Chevy C10 rear drum brake woes. please help.
Quote:
Last edited by Gumby83; 08-22-2024 at 06:50 AM. |
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08-22-2024, 09:17 AM | #13 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
If you have gone from manual brakes to power-assisted brakes, you MUST move your master cylinder pushrod down to the lower hole on your brake pedal arm. If your brake pedal arm only has one hole, you need to drill a new hole one inch lower on the arm. If not, you are not getting enough travel on the pushrod.
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08-22-2024, 09:19 AM | #14 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
This was just discussed back in June - moving the pushrod to the lower hole corrected the issue.
https://67-72chevytrucks.com/vboard/...d.php?t=852953 |
08-22-2024, 02:54 PM | #15 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
Gumby83 I had this same problem. Here is my setup- 1964 C10, LWB Stepside, 350, 700r4, 1987 front cross member swap along with rear diff. Even used the PS and brake booster/master cylinder from the 87. Replaced all components like OP and then got lucky to see a thread started on the on the subject. Its was the thread that MikeN calls out in his post. I drilled my brake pedal and moved the rod like MikeN said. Rock hard pedal, and all brakes work properly now.
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08-22-2024, 07:14 PM | #16 | |
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Re: 65 Chevy C10 rear drum brake woes. please help.
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08-22-2024, 07:16 PM | #17 | |
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Re: 65 Chevy C10 rear drum brake woes. please help.
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Yesterday, 05:10 PM | #18 | |
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Re: 65 Chevy C10 rear drum brake woes. please help.
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Yesterday, 05:12 PM | #19 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
Heres a few pics
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Yesterday, 07:15 PM | #20 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
Hole should be one inch lower from the original position... not higher.
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Today, 02:33 AM | #21 |
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Re: 65 Chevy C10 rear drum brake woes. please help.
This is where i hit the conundrum, do i drill a hole 1 inch lower and ignore the install instructions for the streetbeast hydrobooster or do i go higher to follow the install instructions? the pedal is hard only 3-4 inches into its travel. So its unlike the issues with other fellas boosters that almost go to the floor. Going to try bleeding with this blue screw first and see if a combination of that and the new drums do the trick. That will be tomorrows adventure.
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