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proportioning valves

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GremlinP38 View Drop Down
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    Posted: Mar/22/2018 at 9:08pm
I have a Machine project car that someone swapped single piston calipers into. i still has he proportioning wheel ahead of he back axle, but with he single piston system should the valve sill be in the same circuit? i know there are adjustable valves you can buy. The car has sat enough years that it is going to get nicopp lines and a going through of he brake system and id like to put a different valve in the correct circuit while Im at it, if it is even necessary. For all i know the original valve might still be fine with the fronts.
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billd View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Mar/22/2018 at 9:19pm
Proportioning valve goes in the line to the REAR brakes. 
Personally, I'd try it just where it is, new lines, however.

Doesn't matter how many pistons are in the caliper as far as where a proportioning valve would be - it always is in the line to the rear brakes. It basically helps balance the braking system when there's front disk/drum rear. It reduces pressure to the rear brakes to help prevent them from locking up.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401MATCOUPE Quote  Post ReplyReply Direct Link To This Post Posted: Mar/23/2018 at 4:30am
I have 2 aMX/Javelin with the brake swap and rear proportioning valve and the brake system works perfect....leave it alone and you will be fine, I also convert a 67 Ambassador from Drum to single piston Bendix Caliper and put the rear factory valve in place and it alos work perfect.
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GremlinP38 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GremlinP38 Quote  Post ReplyReply Direct Link To This Post Posted: Mar/26/2018 at 10:05pm
Thanks! I had been told that the single piston needed the proportioning valve moved to the front circuit and wondered about that.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Mar/26/2018 at 10:28pm
Proportioning valve is always in line to the rear brakes. What it does is literally reduce pressure to the rear brakes.
They are especially important during heavy braking when the weight shifts to the front of the car, helping to prevent rear wheel lock up as the weight shifts away from the rear wheels. 
The only valve specific to the front wheels is the metering valve, and that wasn't always used - it restricted pressure to the front brakes until the pressure reached a certain level to overcome the rear shoe return springs. 
All vehicles have a pressure differential SWITCH which is not a valve at all but a shuttle or piston that moves away from the circuit with pressure higher than the other circuit and triggers a warning light. The pressure should be equal coming out of the master cylinder and if it's more than so many pounds different, a fault is assumed. The pressure differential SWITCH warns of drastically different pressures but doesn't actually take action other than trigger a light. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GremlinP38 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/12/2018 at 7:06pm
Thanks everyone!
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