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Only One Brake Working |
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nashman50 
AMC Apprentice 
Joined: May/21/2021 Location: Pennsylvania Status: Offline Points: 39 |
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 Topic: Only One Brake WorkingPosted: Jun/04/2021 at 3:35pm |
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Hi Everyone,
Only the left front wheel brake is working on my 71 Ambassador. Wheel cylinders, hardware kits, and shoes have been replaced on all the wheels. The brakes were very difficult to bleed and we didn't get much fluid out of them when my dad and I were bleeding them. I was thinking that it might be the proportioning valve, but it seems like it just might be a switch on the firewall and not a combination valve. The car has all drum brakes, 10x2 1/2" in the front and 10x1 3/4 in the rear. Does anyone have any ideas of what it might be if it actually is the proportioning valve on the firewall or possibly the master cylinder or booster? Thanks!
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First_Gear
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Joined: Jan/18/2010 Location: Mukilteo WA Status: Offline Points: 644 |
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Posted: Jun/04/2021 at 4:06pm |
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Did you replace the master cylinder? If so did you bench bleed it first? It sounds like it just needs more bleeding to be honest.
The other possibility is that you put the self adjusters in the wrong places. They are different left to right. no proportioning valve on a drum -drum car.
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Trader
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Joined: May/15/2018 Location: Ontario Status: Offline Points: 6881 |
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Posted: Jun/04/2021 at 7:01pm |
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Is the brake light on?
It sounds like the combination valve has tripped/stuck during bleeding and is only providing braking for the front. Left side may be just a hair better at operation the then the right. Remove and ensure the combination valve is clean and all parts are free to move. Then gravity bleed from the rear to the front. Pedal or vacuum bleeding can trip these valves if not done very slowly. |
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RandyB
AMC Nut
Joined: Aug/04/2020 Location: Florida Status: Offline Points: 462 |
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Posted: Jun/04/2021 at 8:39pm |
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Did you bleed the brakes in the right order?
That is the number one reason for brake issues |
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Randy B
68 Javelin SST 343 73 Charger Rallye 340 triple Blk |
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troutwilly
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Joined: Sep/14/2007 Location: Carriere, MS Status: Offline Points: 992 |
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Posted: Jun/04/2021 at 9:12pm |
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Once you've checked and ruled out the master cylinder and distribution block, it could be the flex hoses connecting the solid lines to the suspended components. They collapse/swell on themselves over time. Look good from the outside and flex OK but are plugged inside. Disconnect them from the wheel cylinder side and see if you get fluid to flow. If not, disconnect them from the frame side and check for fluid flow. But it sounds like the distribution block is not functioning correctly.
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Bill O.
70 AMX |
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ramblinrev
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Joined: Dec/28/2008 Location: Wisconsin Status: Offline Points: 11538 |
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Posted: Jun/04/2021 at 9:56pm |
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IIRC the left front on a drum brake car is the line that doesn't go through the pressure differential switch/block (no combination valve or proportioning valve on your drum brake car). (That's how it is on my '74 Hornets) So I would get a rebuild kit and carefully pull that apart, or else keep bleeding. Have you tried opening all 4 bleeders and letting it gravity bleed? Keep the master as full as you can. Keep the lid loose so that fluid can flow. Let it sit a little while and see what it does. I'm inclined to think you have a bubble or blockage somewhere
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74 Hornet Hatchback X twins (since 1977)
62 American Convertible (still worth the $50 I spent in 1973!) AMCRC #513, AMO #384 70 AMX 360 4-speed (since 1981) |
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nashman50
AMC Apprentice
Joined: May/21/2021 Location: Pennsylvania Status: Offline Points: 39 |
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Posted: Jun/06/2021 at 5:55pm |
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Tearing apart the distribution valve and replacing the master cylinder are next on the list. The brake light is on, so I think it's probably the distribution valve.
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tomj
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Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544 |
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Posted: Jun/06/2021 at 11:46pm |
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Just today I had a wheel cylinder that simply would not bleed at all. I took the bleeder out entirely, and poked a wire in the hole. There was crud blocking it, immediately fluid came out and it then bled fine. (This is on a relatively new-to-me car, the wheel cyls were allegedly recent, no leaks or crud visible under the boots.) |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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nashman50
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Joined: May/21/2021 Location: Pennsylvania Status: Offline Points: 39 |
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Posted: Jun/23/2021 at 9:28pm |
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Finally got all the brakes working. Replaced everything including the master cylinder. Thanks everyone!
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ramblinrev
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Joined: Dec/28/2008 Location: Wisconsin Status: Offline Points: 11538 |
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Posted: Jun/23/2021 at 9:40pm |
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Good work! Sometimes it's tricky, but still involves checking and rechecking the basics! |
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74 Hornet Hatchback X twins (since 1977)
62 American Convertible (still worth the $50 I spent in 1973!) AMCRC #513, AMO #384 70 AMX 360 4-speed (since 1981) |
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