No brake pedal pressure

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Jays60rag
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No brake pedal pressure

Post by Jays60rag » Sat Sep 12, 2009 9:23 pm

I have a 1960 bug that I put a dual circuit master cylinder into. I replaced all of the hard brake lines and one of the flexible lines. I absolutely cannot get any pedal pressure. I am now on my third master cylinder and the problem is the same. I think I can rule out the master cylinder now. I have checked all of the brake line unions and they are all tight. All four wheel cylinders are brand new. I can pressurize the system via an air compressor and the fluid bleeds out all 4 wheels. I just can't get any pressure to build up when you push the pedal down. I don't hear any air leaking except for a little at the cap of the reservoir when the pressure builds to about 30 psi within the reservoir. I am now completely out of answers.The master cylinder is displacing fluid as normal, but there is no pressure to expand the wheel cylinders. The brakes just don't work. If anyone can help me I would be elated. I have no more patience for this, but I will not let this thing beat me.

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Ryno
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Post by Ryno » Sun Sep 13, 2009 4:57 am

I would try isolating the wheel cylinders from the rest of the system. Put a clamp of sorts on the flex lines at each wheel. If you get pressure then, remove one clamp at a time until your pedal goes away, then you know where to focus.

You could do the same with the master also. You would just need to go and get some plugs for that.
Ryan

1985 Westfalia

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RSorak 71Westy
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Post by RSorak 71Westy » Sun Sep 13, 2009 1:57 pm

did you bench bleed the master cylinder?
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Rick
Stock 1600 w/dual Solex 34's and header. mildly ported heads and EMPI elephant's feet. SVDA W/pertronix. 73 Thing has been sold. BTW I am a pro wrench have been fixing cars for living for over 30 yrs.

vdubyah73
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Post by vdubyah73 » Sun Sep 13, 2009 4:02 pm

I'll bet you're pushing air into the MC every time you pressure bleed it. Try turning the pressure down to about 5-10 psi. Check the fluid level in the reservoir at least once for every wheel. I'm like a jack in the box every time I do this, checking the reservoir level a couple times as I bleed each wheel.
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Jays60rag
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Post by Jays60rag » Mon Sep 14, 2009 5:59 pm

I don't exactly know what a bench bleed is. I am sure that the idea is to get fluid to run through the new master cylinder so I don't push so much air out through the lines. I installed the master cylinder and bled while it was in the car. I saw the fluid pour out of all three out ports. I then attached the brake lines. I have pressurized the system and there are no apparent leaks. The reservoir has never been drained when bleeding. I do think that I am pushing air into into the master cylinder each time I pump the brakes, but I don't know how to stop that.

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Jays60rag
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Post by Jays60rag » Mon Sep 14, 2009 10:15 pm

I want to thank those who responded to my plea for help. I used plugs in the master cylinder to isolate the problem (a suggestion that was offered to me). It turns out that the brand new wheel cylinder I put in the passenger front was not adjusted properly. I worked on that for quite a while before I could get any pedal pressure. Then it happened. I had to readjust every wheel and bleed the system several times, but now I have brakes. I can STOP working on them, no pun intended. Thank you for helping me out.

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