Installing an adjustable prop valve on are cars

[bgbmxer]

http://i268.photobucket.com/albums/jj17/bgbmxer/7827DCC0-BFBB-4DBA-9B71-C4D26B094971-1091-000000B167A74E95.jpg

Ok here's what I got my concern is that coming out of your mc it goes into the stock prop valve. Should I delete the stock one all together if I'm running my adjustable one? My other question is since I'm going from 2 lines into one at the adjustable prop valve then back into 2 for the rear brakes will this work or will I be losing to much fluid movement. My idea was to upsize the lines when they tee into one but the prop valve is set up for 5/16 also. Any advice or anyone even runnin a adjustable proportioning valve who's doing any kind of road coarse stuff

[turbovanman²]

Well you have to redo your lines as the brakes are a split diagonal system, meaning LF and RR, RF and LR so you'd have to remove the prop valve and redo them so the fronts are on one circuit and the rears are on one circuit.

[bgbmxer]

Well you have to redo your lines as the brakes are a split diagonal system, meaning LF and RR, RF and LR so you'd have to remove the prop valve and redo them so the fronts are on one circuit and the rears are on one circuit.

Planned on redoing all of them anyways. Didnt know that's how they were split but I have seen some cars like that. Which port is which on the mc so I don't screw that up haha. I'll build from there on.

[turbovanman²]

Planned on redoing all of them anyways. Didnt know that's how they were split but I have seen some cars like that. Which port is which on the mc so I don't screw that up haha. I'll build from there on.

Doesn't matter, the piston sizes are the same, hence why its a split system, :p So I would use the front port for the fronts and the rear for the rears, :eyebrows:

[bgbmxer]

Doesn't matter, the piston sizes are the same, hence why its a split system, :p So I would use the front port for the fronts and the rear for the rears, :eyebrows:

Learn something new everyday. Any thoughts on how the lines will go from 2 to 1 and back to 2 again and restricting flow?

Or actually I can run 1 back to the prop valve and split after that and split the front right after it comes out of the mc

[turbovanman²]

I would run one line to the prop valve, then split after it. You could retain the prop valve for the fronts if you wanted or just split the fronts after running one line out of the MC or you can just run 2 prop valves on the rear lines and leave everything else alone.

[bgbmxer]

I would run one line to the prop valve, then split after it. You could retain the prop valve for the fronts if you wanted or just split the fronts after running one line out of the MC or you can just run 2 prop valves on the rear lines and leave everything else alone.

All the lines need done anyways. They are original and enough said there. And running 1 line off the mc and splitting it seems the way to do it and simplify it at the same time. 2 prop valves just seems not needed but I could be wrong. Plan on mounting the one prop valve in the cabin of the car also.

[bgbmxer]

Isn't the brake switch within the prop valve?

[turbovanman²]

Isn't the brake switch within the prop valve?

Brake switch for the lights is on the brake pedal, the warning light is in the prop valve when you have a hydraulic failure.

[bgbmxer]

Brake switch for the lights is on the brake pedal, the warning light is in the prop valve when you have a hydraulic failure.

What are my options for that. Pull a lightbulb or jump it out so I don't have a light

[shackwrrr]

Just unplug it, it grounds to turn the light on so if its not hooked up it'll never light up.

[Shadowv4l]

i am also looking into running a adjustable prop valve - for the street. It looks like i can only find a prop valve that has 2 lines going out for the front brakes and only one outlet for the rear ( I have swapped rear disc on a shadow) . It looks like the single outlet for the rear is the one with the adjustment. My issue is deciding how to split the single line leaving the prop valve into two seperate lines going to the rear calipers.

or..... Should I just gut the Stock prop valve so it's even on all 4 corners and just put two seperate adjustable valves on each rear line near the rear caliper?

I'm thinking the second option would be alot easier to install, the only trick would be to get both RR and LR exactly the same pressure. Maybe I'll get the valves with the guages attached to them and I'll set up my go pro to watch the gauges as press on the pedal , lol. - or just get a freind to watch them for me.

[shackwrrr]

Run it F/R split. The only reason for the diag split is for people that neglect their cars and ignore possible failures in brake lines, either rust or chafing. With proper inspections and maintenance the brake lines should be fine.

If you run F/R split then you can just run a tee to split off the rear brakes and hook the fronts up to the 2 ports on the prop valve.

[Shadowv4l]

Thats what i was thinking... but with that you are suggesting the "gut the stock prop valve" idea?

Also I was thinking about using a newer car's prop valve of somewhat equal size and weight. I can't seem to find the correct prop valve. No matter what I do I always end up with my rear brakes locking up, I can't even get my fronts to lock. Trail braking works great but if I have to panic stop on the highway i'll be screwed.

[shackwrrr]

Remove the stock, add adjustable aftermarket. Route front lines to aftermarket front outlets, Run the one line from the aftermarket unit to a TEE with both rear connected to it. Adjust as needed.

The other option is to route both front lines to a tee then to one port on the master cylinder. run the second port on the master cylinder to an individual prop valve then to a tee for the rear lines. This is the way I am going, much cheaper, here is a diagram. This also allows the prop valve to be easily mounted inside where it is easily adjusted on the fly.


Just follow this diagram, rear is on the left and front on the right. (master cylinder is backwards in picture)
42306

[rbryant]

Note that most aftermarket prop valves usually only control the crack point and have a fixed slope of .57 which isn't exactly right for a FWD rear disc car.

That means you will basically have options similar to the light blue and pink lines:
http://www.turbo-mopar.com/forums/attachment.php?attachmentid=25482

I am not sure what the min and max crack points are on those valves but you can just think about adding more lines parallel to the light blue or pink lines starting from higher or lower points on the differential line.

http://www.turbo-mopar.com/forums/knowledge.php?title=Brake-and-Wheel-Systems:Proportioning-Valve-Options

-Rich

[Shadowv4l]

ok, I guess the question would be
What will this .57 do in terms of braking behavior?
More rear wheel lock sooner? or not enough braking to rear causing back end to come out because front is doing all the braking?

Right now my car just doesnt stop fast enough and when I really stomp on it and slightly turn the back end wants to come out, altho it's fun it is not safe in a panic situation. Had a deer jump out in front of me the other night and I slammed the brakes only to drift around the thing instead of a steady stop.
-Also my rear pads wear much faster than my front and I noticed this even after getting a different prop valve and different pad/rotor materials (i think Gray tag)
I also got a new MC from a minivan IIRC and i'm running ATE blue fluid.
I wouldn't mind finding a yellow tag Prop valve but the yards around me aren't the best places to get so lucky.

---------- Post added at 10:45 PM ---------- Previous post was at 10:40 PM ----------

I've been trying to duplicate the braking that my csxt has because it is awesome compared to my 94 shadow (the one with the issue) , So far no such luck. The pedal is really firm now since the MC swap which i like but something just isn't right. It's almost like a less wild version of having the rear drum prop valve on the car with converted rear disk - drove it like that for a year and a half. That sh!t was crazy.

[rbryant]

ok, I guess the question would be
What will this .57 do in terms of braking behavior?
More rear wheel lock sooner? or not enough braking to rear causing back end to come out because front is doing all the braking?

Right now my car just doesnt stop fast enough and when I really stomp on it and slightly turn the back end wants to come out, altho it's fun it is not safe in a panic situation. Had a deer jump out in front of me the other night and I slammed the brakes only to drift around the thing instead of a steady stop.
-Also my rear pads wear much faster than my front and I noticed this even after getting a different prop valve and different pad/rotor materials (i think Gray tag)
I also got a new MC from a minivan IIRC and i'm running ATE blue fluid.
I wouldn't mind finding a yellow tag Prop valve but the yards around me aren't the best places to get so lucky.

---------- Post added at 10:45 PM ---------- Previous post was at 10:40 PM ----------

I've been trying to duplicate the braking that my csxt has because it is awesome compared to my 94 shadow (the one with the issue) , So far no such luck. The pedal is really firm now since the MC swap which i like but something just isn't right. It's almost like a less wild version of having the rear drum prop valve on the car with converted rear disk - drove it like that for a year and a half. That sh!t was crazy.

The .57 is the slope of the line after the crack point.

Basically the slope is the percentage of pressure that will go to the rear brakes after the crack point. In the graph above the front brakes always get the pressure that is on the differential line. The rear brakes then get the pressure of the other colored lines depending on the prop valve you use.

The brakes will send the same pressure to the front and rear until the crack point. At that time the rear brakes will start to get less pressure than the fronts. Most of our cars have slopes of .27 or .43 meaning that after the point when the pressure is reduced to the rear it is reduced by a much greater amount than what the aftermarket valve will provide.

It is possible to lower the crack point on the aftermarket adjustable prop valve such that the rear brakes start getting less pressure sooner. Lowering the crack point can reduce the rear pressure but it has the effect of giving less rear brake sooner rather than less rear brake later.

Earlier crack point = less rear brakes at lower pressures.
Later crack point = more rear brakes at lower pressures

Higher slope = more rear brakes after the crack point.
Lower slope = less rear brakes after the crack point.

As you can see in the above chart that I made, there are combinations that give similar results with various combinations of crack point and slope but the aftermarket valves really only allow you to change one of the things that affect rear brake pressure.

I would suspect that unless you changed to larger rear discs or something that it is more likely that your front brakes have a problem (buildup of gunk inside of the piston, etc) that aren't allowing them to do the work.

-Rich

[Shadowv4l]

sad part is The front calipers are brand new (a week old) and the MC is a few months old and I also have new steel lines in the front. This is why im turning to the adjastable prop valve idea. I just wanted to make sure it wouldnt make anything worse than it is, I figured by having some kind of adjustment I could play with it until braking felt better and more stable. Im starting to think the gray tag prop valve I have is really a rear drum prop valve and not a disk car one.

[Shadowv4l]

ok... just did some lookin' the prop valve I have now on my 94 shadow is from a 1990 Spirit ES with 10 inch 4 wheel disk brakes.
AA 14" disc-disc 400psi .27 White tag - ??????

.27 sound right for that car?

---------- Post added at 09:05 PM ---------- Previous post was at 09:02 PM ----------

so i guess im looking for a .43 yellow tag instead of using this .27 white tag.

[Shadowv4l]

unless im reading the graph worng http://www.turbo-mopar.com/forums/knowledge.php?title=Brake-and-Wheel-Systems:Proportioning-Valve-Options

If i'm having a rear lockup issue now wouldn't the yellow make it worse since it will see more pressure for longer?

from what i'm seeing the gray 500/.27 Lbody prop valve would more likely give my front brakes more of the work load solving my rear brake lockup issue. Or am I reading this all wrong?

[Reaper1]

You sure that white prop valve isn't off of a Shelby Z? Those have a very notorious problem with locking the rears before the fronts. The slope isn't on that graph that Rich has posted, but I *think* I posted the specs in his thread. I installed a '90 yellow tag one and it pretty much solved the issue. That valve can be found on various cars from '89 and '90 and they DON'T have to be disc/disc cars! Mine came off of a '90 Daytona V6 disc/drum car. My other '90 V6 Daytona has the same valve on it.

[rbryant]

unless im reading the graph worng http://www.turbo-mopar.com/forums/knowledge.php?title=Brake-and-Wheel-Systems:Proportioning-Valve-Options

If i'm having a rear lockup issue now wouldn't the yellow make it worse since it will see more pressure for longer?

from what i'm seeing the gray 500/.27 Lbody prop valve would more likely give my front brakes more of the work load solving my rear brake lockup issue. Or am I reading this all wrong?

The lbody valve will have more of a rear lockup problem.

The front/rear have the same pressure UNTIL 500psi with that valve. After that the pressure to the rears is dropped but it happens too late.

The max rear pressure (when the front is 1000psi) is on the 500/.27 valve is pretty good (around 625psi similar to the yellow tag valve) but at 500psi it send too much pressure to the rear (500 instead of 400 with the yellow tag valve).

Basically the lower left is lower pressure, the higher right is higher pressure.

A 300/.27, 300/.43, 400/.27, or 400/.43 are all better options.

-Rich

[bgbmxer]

I re did my brakes the same as the diagram with the adj proportioning valve shows. It was a pain redoing all the lines but I like knowin it's all new and not gonna rust out. Your saying that the adjustable proportioning valve works like a pressure relief valve and not like an Orfice to restrict flow per say? I took mine apart and it has a spring in it so I gues that would make sense. I'm hoping with some testing it will work just fine tho.

[rbryant]

I re did my brakes the same as the diagram with the adj proportioning valve shows. It was a pain redoing all the lines but I like knowin it's all new and not gonna rust out. Your saying that the adjustable proportioning valve works like a pressure relief valve and not like an Orfice to restrict flow per say? I took mine apart and it has a spring in it so I gues that would make sense. I'm hoping with some testing it will work just fine tho.

Yes they adjust spring pressure. The quick fix for an lbody is probably to change the spring with one from a rear disc car (to lower the crack point) but I haven't tried it yet... when I get some time I will have to look into modifying our stock valves to be adjustable.

[bgbmxer]

Yes they adjust spring pressure. The quick fix for an lbody is probably to change the spring with one from a rear disc car (to lower the crack point) but I haven't tried it yet... when I get some time I will have to look into modifying our stock valves to be adjustable.

My stock prop valve is gone so there's no going back now. Gonna make the adjustable prop valve work. It works on other cars so I don't see why it won't on this car too