Brake proportion valve
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Mountain Pass
Joined: Apr 2012
Posts: 196
Likes: 1
Brake proportion valve
1976 Ford F-250 standard cab standard bed 4x4 high boy with 390 power steering power brakes dual piston front disc brakes drum rear brakes
Trying to decide what to do with the brake differential valve. I have the original but it's rusty nasty looking. I am going to have a completely new brake system, calipers, wheel cylinders, lines, brake booster brake master cylinder.
I started to take my valve apart, I was hoping I could just clean it up and put it back together, but I can't get the spring plunger bleeder deal out. Maybe it's rusted in? I got the proportioning valve and brake pressure switch out and all the lines. And there are a few seals I would have to get.
Should I go with an after market valve? If so how do I decide which one to go with? How difficult is it to get it dialed in to work well? Mounting in same location? fittings size? I would like to find An easy to use replacement.
How am I going to be able to bleed the air out of this completely new system? Any tips or tricks?
Thank you
Steve
Trying to decide what to do with the brake differential valve. I have the original but it's rusty nasty looking. I am going to have a completely new brake system, calipers, wheel cylinders, lines, brake booster brake master cylinder.
I started to take my valve apart, I was hoping I could just clean it up and put it back together, but I can't get the spring plunger bleeder deal out. Maybe it's rusted in? I got the proportioning valve and brake pressure switch out and all the lines. And there are a few seals I would have to get.
Should I go with an after market valve? If so how do I decide which one to go with? How difficult is it to get it dialed in to work well? Mounting in same location? fittings size? I would like to find An easy to use replacement.
How am I going to be able to bleed the air out of this completely new system? Any tips or tricks?
Thank you
Steve
Laughing Gas
Joined: Mar 2015
Posts: 885
Likes: 2
From: Pittsburgh
If you're going to have an entirely new brake system, why keep the old valve? Mounting location is probably best to be kept in the same position. Bench bleed the master before installing, then bleed the other lines like normal.
Senior User
Joined: Feb 2016
Posts: 121
Likes: 3
From: Velva ND
I went with the proportioning valve from bronco graveyard and bought there stainless brake lines. They get there lines from inline tube. I am having trouble with some of the fittings leaking. Everything is new so I don't no what the trouble is. I would definitely ditch that old proportioning valve.
Fleet Mechanic
Joined: Feb 2011
Posts: 1,410
Likes: 42
From: Michigan
I went with the proportioning valve from bronco graveyard and bought there stainless brake lines. They get there lines from inline tube. I am having trouble with some of the fittings leaking. Everything is new so I don't no what the trouble is. I would definitely ditch that old proportioning valve.
Senior User
Joined: Feb 2016
Posts: 121
Likes: 3
From: Velva ND
Ya that's what I did, snugged them up and backed them off a few times. The only way I got a couple to seat was to tighten them up about as hard as I could. Maybe I got a bad batch.
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Lead Driver
Joined: Apr 2011
Posts: 6,399
Likes: 40
From: El Dorado, Arkansas
The brake line fittings themselves don't seal the lines off. They only push the flares on the ends of the tubes into the seats. The flare is what seals the lines off.
Stainless steel is much harder than plain steel or NiCopp brake line tubing so it doesn't conform and seal off as easily.
Stainless steel is much harder than plain steel or NiCopp brake line tubing so it doesn't conform and seal off as easily.
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Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
Stainless has a flare degree of 37* whereas the regular steel 3/16" tubing is at a 45* flare. You can remedy this situation by tightening the bejesus out of it, But first make sure the flare is seated properly and square....as ultraranger stated.
Lead Driver
Joined: Apr 2011
Posts: 6,399
Likes: 40
From: El Dorado, Arkansas
Stainless can be double flared but it's much more difficult to do (compared to steel or NiCopp lines) with regular flaring tools without ending up with deformed or cracked flares in the stainless tubing.
When making double flares, it's OK to crank down on the 1st stage of the double flaring process. However, you don't want to do the same on the 2nd stage of making the double flare. The final compression of the double flare process should come when you tighten the line into the MC port, brake valve port or the flexible brake line port.
If the double flare stage is already compressed flat against the 1st stage, at the time you go to tighten the line into the port, there's no 'crush' left in the double flare to form to the port seat to seal the flare off.
Postmaster
Joined: Nov 2011
Posts: 2,553
Likes: 10
For the prop valve, the Bronco Graveyard offering sounds good. In line tube also offers a "non exact" replacement.
As far as lines go, I prefer mild steel because it seals better and can be modified with common tools. SS is hard to work with and needs high end flaring tools.
You could use a generic prop valve on the rear brakes lines only (eg. Wilwood). This would require customization of the lines. Also adjustment by trial and error. May work OK but no experience... though I may try it in the future.
As far as lines go, I prefer mild steel because it seals better and can be modified with common tools. SS is hard to work with and needs high end flaring tools.
You could use a generic prop valve on the rear brakes lines only (eg. Wilwood). This would require customization of the lines. Also adjustment by trial and error. May work OK but no experience... though I may try it in the future.
New User
Joined: Apr 2016
Posts: 10
Likes: 0
The idea with a proportion in valve is that you want the front to lock up before the back, this seems backward but the basic result is that when you lock up the brakes you go straight instead of fishtailing. The easiest way I know to do this is to wait for a rainy day and find a place that you don't have to worry about traffic, and start with the the valve adjusted with more to the front (more pressure to front wheels) and slowly adjust more pressure to the rear until you lock up the rear wheels first, then adjust it back 1/4-1/2 turn until the rear no longer locks up. There might be a better/safer way to do this but this is the way I know how to do it.
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