My 41 Ford COE has a brake problem. I need ideas as to how to fix it. When I drive the truck and press the brake pedal, the front brakes grab hard for a split second and then release and the brake pedal feels normal after that. If I hit the pedal again,the same situation occurs. Hard or soft on the pedal makes no difference. Here is the design - front disks (1-ton R-30), GM dually rear end, factory GM prop valve, factory 3/4 ton GM master with 10" booster off running truck (not hydroboost), Master located above front calipers. Stock brake line sizes. Weight distribution different - SBC motor under bed, heavy flatbed. I am thinking the following possibilities: bad prop valve, air in rear lines, prop valve wrong design for weight distribution, master cylinder not matched to work with the 1-ton brakes, rear brakes out of adjustment. I talked to the tech at Wilwood and they suggested removing the factory prop valve and just using an in-line valve on the front lines. Can anyone shed some light on what may be the problem? This is not my first hotrod build, but this is the first time I've ever used 1-ton brakes and a factory prop valve. Help!!!!!
Right off hand it sounds like a bad or non-existant metering valve. This delays the front brakes from engaging for a split second to allow the rear drum brakes to engage first. Generally built into a stock proportioning valve. Speedway has one #910-31363.
I like that thought. Before I installed my prop valve, It was really nasty and when I cleaned it, I wonder if I damaged it somehow. I think I will go to U Wrench it and buy another factory prop valve (10 bucks) and try that. Thanks.
Thought I would sum up the problem(s). The front calipers are Bendix units. I found one seemed loose. They mount with wedges and mini leaf springs. The slock wedges were too small. They sell oversize pieces and that fixed part of the problem. I then discovered I also had a "new" lower ball joint that was bad. I replaced that and lastly I discovered the rear brakes needed to be rebuilt as some parts were rusted stuck. The brakes still grab a little bit, but the rears need to adjusted a bit more after I drive the truck a few times. It is much improved.
Loose parts will cause a grab when they try to pick up the slack under braking. What are the calipers from, maybe a '73-76 Ford Torino? Bob
I suspect the front rubber hoses. My mid 90's Chevy PU did that and got progressivley worse on the p*** side. Turns out the rubber hose had a bad habit of de-laminating on the inside. Would have a little flap come loose and hold pressure. Did you reuse stock hoses or are they aftermarket pieces?
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