1974 Highboy Brake Problem
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1974 Highboy Brake Problem
Hi, i'm looking for some advise. My truck has a 360 with drumbrakes front and rear. It has new wheel cylinders and new shoes all they way around, as well as a rebuilt mastercylinder and booster. Ive bled the brakes manually and then with manual "reverse bleeder." I've adjusted the plunger that sits between the master cylinder and the booster. The problem is that I can't get a good brake pedal. It has good stopping power, but it is all the way at the bottom and grabs mostly in the front.
Any advise is appreciated.
Any advise is appreciated.
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Ya, I adjusted the shoes outward to the point were the drums slide on with a snug fit, but the rotor can be spun by hand and free wheel.
I was thinking maybe I need a new brake proportioner, but when I manually pled the brakes I was pushing fluid to all 4 wheels. I heard that a brake proportioner is designed to cut fluid to the front or rear if a line blows. So if I'm getting fluid to all four wheels then my brake proportioner must be working. I'm not sure sure if that is true.
I was thinking maybe I need a new brake proportioner, but when I manually pled the brakes I was pushing fluid to all 4 wheels. I heard that a brake proportioner is designed to cut fluid to the front or rear if a line blows. So if I'm getting fluid to all four wheels then my brake proportioner must be working. I'm not sure sure if that is true.
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Joined: Nov 2006
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From: Pa.
I am not sure with the 1974 drum brakes if they have a proportioning valve similar to that of the disc brake front but with that system you must have the pin out to bleed .. "you push in on 250/350 and pull out on bronco/100/150"
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From: Townsend, MT
Nope. It should have one down on the frame.
Actually, it's not really a proportioning valve, but more of a safety. I.E. if a front brake line were to blow out, the piston would slide to block the front circuit so your back brakes would still work.
Actually, it's not really a proportioning valve, but more of a safety. I.E. if a front brake line were to blow out, the piston would slide to block the front circuit so your back brakes would still work.
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I must have what 1972RedNeck is talking about. My " Proportioning valve" is located in between the front left cab mount and the frame. I'll take a look to see if my proportioner is similar to that of the one in the 75 diagram. Thanks for the info.
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From: Townsend, MT
A little update. Thursday I had a front brake line spring a leak (extreme deja vu?) Coming to a corner on a gravel road, I hit the brakes. The pedal sank about twice as far as normal (just enough to get that "oh *****" feeling) but then firmed up and proceeded to lock the back brakes.
It turns out that the deer I smucked about two weeks ago kinked the rubber line and for some reason it took two weeks to spring a leak.
On a side note, the proportioning valve (or whatever you want to call it) off of a '74 highboy does not take the brake bleeder tool. It has no pin or anything sticking out and I really don't understand how they work but I know they do.
It turns out that the deer I smucked about two weeks ago kinked the rubber line and for some reason it took two weeks to spring a leak.
On a side note, the proportioning valve (or whatever you want to call it) off of a '74 highboy does not take the brake bleeder tool. It has no pin or anything sticking out and I really don't understand how they work but I know they do.
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