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Discussion Starter · #1 ·
I just changed the single diaphragm booster shown in this photo to a double diaprhagm booster, so had to bleed the front and rear brakes. The car has 4 wheel Wilwood disc brakes. When bleeding the front calipers, I get probably 4 times as much fluid with each pump as I get from the rear calipers. Is this normal? I know the front brakes do most of the braking, but I would have thought that the amount of fluid pushed out would be approximately the same at each caliper? Thanks, Bill
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First, nice looking install, outstanding workmanship. I notice you have a proportioning valve which may cut down on the amount of fluid going to the back. Proof of the system is a solid pedal. If you don't have to pump it up then all the air is out. In the past I have had problems getting all the air out of the back. Have you put pressure on the system yet? I mean use the pedal to press hard and see if there are any leaks.
 

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Discussion Starter · #3 ·
First, nice looking install, outstanding workmanship. I notice you have a proportioning valve which may cut down on the amount of fluid going to the back. Proof of the system is a solid pedal. If you don't have to pump it up then all the air is out. In the past I have had problems getting all the air out of the back. Have you put pressure on the system yet? I mean use the pedal to press hard and see if there are any leaks.
Yes, I've held pressure as hard as I could on the pedal with the engine running (although I don't create much vacuum) and checked for leaks. All looks ok. I don't have to pump up the pedal, even after sitting all night, but the pedal isn't really rock hard, but does feel solid and I can feel the pedal pull down a bit when I start the engine.
 

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When the pedal drops like that it indicated the booster is working fine. Sounds to me as if everything is working as it should. I suspect the proportioning valve is restricting fluid to the rear. I know you didn't ask this but I would like to comment on the proportioning valve. I don't like them! They are preset for a completely different size vehicle, different size tires, different M/C, different booster, different weight distribution. Outside of that they are a perfect match for any application. Your call.
 
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