Brake help!
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Joined: May 2002
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I too have front discs/rear drums and a proportioning valve. Rumor has it that if your m/c is lower than the calipers then you should have a residual valve. My m/c is about level with the calipers and brakes work OK.
Logistics Pro
Joined: Oct 2002
Posts: 4,489
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From: Valley Center, CA
Joners, my M/C is under the cab mounted to the frame. Sac Vintage Ford supplied it and they said that I would need the check valves. However, I have talked to other guys who say they did not use them and thier brakes work fine. So, I would suggest trying it without those pricey check valves first. Sac Vintage said that without the check valves, the brake pedal would need to be pumped each time you wanted to stop. 
But, there is only one way to know for sure. John 
But, there is only one way to know for sure. John
Lead Driver
Joined: Apr 2002
Posts: 8,813
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From: Littleton, New Hampshire
Generally, if you have a firewall mounted master cylinder, you won't need the inline residual valves. However, in every floor mounted master cylinder system I have done, the residual valves were needed. Without them you will have to pump up the brake pedal. That's why I will never use a floor mounted master cylinder again. If you have already finished your brake system, then it's worth a try to leave them out, but if you are still putting the brake system together, I'd go ahead and put them in so you won't have to redo them later. Putting the inline valves in will not harm anything even if you don't need them...but a pair will cost you about 50 bucks extra. 
Vern
Vern
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Joined: Aug 2003
Posts: 1,243
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From: Michigan
Hi
It looks like you are going to be using a dash/firewall mounted booster and m/c with this location you don't need the check valves. In most cases if the m/c is below the cab you would need a 10# valve for the front and a 2# for the rear that way you don't get bleed back.
I have the dash mounted combo with a proportioning valve from a 1976 F100 it's worked for the last 15 yrs (well 12 anyway it's been down for a minor tuneup for the past 2 1/2 yrs, thats what happens when you retire and have to much time to screw things up)
Chuck
It looks like you are going to be using a dash/firewall mounted booster and m/c with this location you don't need the check valves. In most cases if the m/c is below the cab you would need a 10# valve for the front and a 2# for the rear that way you don't get bleed back.
I have the dash mounted combo with a proportioning valve from a 1976 F100 it's worked for the last 15 yrs (well 12 anyway it's been down for a minor tuneup for the past 2 1/2 yrs, thats what happens when you retire and have to much time to screw things up)
Chuck
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Lead Driver
Joined: Apr 2002
Posts: 8,813
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From: Littleton, New Hampshire
Originally Posted by merc546
Hi
It looks like you are going to be using a dash/firewall mounted booster and m/c with this location you don't need the check valves. In most cases if the m/c is below the cab you would need a 10# valve for the front and a 2# for the rear that way you don't get bleed back.
Chuck
It looks like you are going to be using a dash/firewall mounted booster and m/c with this location you don't need the check valves. In most cases if the m/c is below the cab you would need a 10# valve for the front and a 2# for the rear that way you don't get bleed back.
Chuck
Actually, the 2 lb goes in the front and the 10 lb in the rear, but I'm sure that's what you meant. It takes more pressure to keep brake shoes close to drums than it does to keep brake pads close to rotors...
Vern
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Junior User
Joined: Dec 2001
Posts: 82
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From: Tucson USA
I'm by no means a brake expert, but everything I have read to date implies drums need a 10 lb check value and disc brakes need a 2 lb check valve if the master is below the wheel cylinder. When master is above the wheel cylinder gravity provides the necessary 2lb pressure for a disc brake but not the 10 lb necessary for drums.
Some master cylinders have check valves built in, e.g. 67-72 Mustang disc/drum master cylinders has a 10 lbs check value built in for the drum line output port but no check valve for the disc line. But I don't have a clue if others do, I just know that particular model does.
Good luck. Stopping is almost as important a going forward.
Rick
Some master cylinders have check valves built in, e.g. 67-72 Mustang disc/drum master cylinders has a 10 lbs check value built in for the drum line output port but no check valve for the disc line. But I don't have a clue if others do, I just know that particular model does.
Good luck. Stopping is almost as important a going forward.
Rick
Lead Driver
Joined: Apr 2002
Posts: 8,813
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From: Littleton, New Hampshire
Originally Posted by koshare
Some master cylinders have check valves built in, e.g. 67-72 Mustang disc/drum master cylinders has a 10 lbs check value built in for the drum line output port but no check valve for the disc line. But I don't have a clue if others do, I just know that particular model does.
Rick
Rick
In addition, all master cylinders made for drums only whether single or dual reservoir had 10 lb internal residual valves. If you use those master cylinders with discs you have to disassemble the master cylinder and remove the 10 lb internal valve. I have done this a few times over the years before dual master cylinders became the norm...
Vern
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