Residual pressure valve location

[bull]

Does it matter which comes first, the 10 psi residual pressure valve or the adjustable proportioning valve? I was going through some diagrams and saw it both ways. Would there be any difference installing it one way or the other?

[Dino]

I guess it would not matter, but I would still stick the residual valve between prop/combo valve and rear wheels.

[John_Kunkel]

The instructions that come with the Wilwood RPV state "install as close a possible to the master cylinder".

[bull]

I guess it would not matter, but I would still stick the residual valve between prop/combo valve and rear wheels.

That's how I have it. I still need a combination valve.

[Dino]

I guess it would not matter, but I would still stick the residual valve between prop/combo valve and rear wheels.

That's how I have it. I still need a combination valve.

This is what I'm getting instead of using the GM style:

http://www.classicdiscountparts.com/products/Mopar-Dodge-Plymouth-Combination-Valve.html

This is also about $70-$80 less than other places.  You may find it cheaper somewhere so if you do, lemme know!   

http://www.classicdiscountparts.com/products/Mopar-Dodge-Plymouth-Combination-Valve.html

[Dino]

Even cheaper

http://www.restorationperformance.com/servlet/the-127166/Mopar-Dodge-Plymouth-Combination/Detail

[bull]

Are metering valves needed?

[tsmithae]

I thought residual valves were in the MC.  I removed my old bake lines and don't remember any residual valves...

[Dino]

Are metering valves needed?

Yes you do or you may be sliding into oblivion under hard braking.

http://www.piratejack.net/index.php?option=com_content&view=article&id=10&Itemid=17

I thought residual valves were in the MC.  I removed my old bake lines and don't remember any residual valves...

True, some MC's have the valve built in so be sure to check yours Bull.  You don't want 2 of them in line!

[bull]

True, some MC's have the valve built in so be sure to check yours Bull.  You don't want 2 of them in line!

Apparently I need to rethink my whole setup. First off, it's my understanding that a front residual valve is not needed unless the MC is below the front calipers, right? So I should not need that. That said, do MCs with residual valves typically have them for both front and rear? Also, why would a residual pressure valve redundancy to the rear (built in MC residual valve + inline residual valve) cause problems? I'm not trying to argue, just wondering.

Is there a way to tell by looking if your MC has a residual pressure valve or do I have to go back and do some research?

According to your supplied link a seperate metering valve should not be necessary when a combination valve is used. If that's the case all I really need to do (I think) is replace my basic distribution valve with a combination valve and then figure out if my MC has a built in residual pressure valve and if so, eliminate my in-line valve. Well, depending on the answer to my question in paragraph one.

[Dino]

True, some MC's have the valve built in so be sure to check yours Bull.  You don't want 2 of them in line!

Apparently I need to rethink my whole setup. First off, it's my understanding that a front residual valve is not needed unless the MC is below the front calipers, right? So I should not need that. That said, do MCs with residual valves typically have them for both front and rear? Also, why would a residual pressure valve redundancy to the rear (built in MC residual valve + inline residual valve) cause problems? I'm not trying to argue, just wondering.

Is there a way to tell by looking if your MC has a residual pressure valve or do I have to go back and do some research?

According to your supplied link a seperate metering valve should not be necessary when a combination valve is used. If that's the case all I really need to do (I think) is replace my basic distribution valve with a combination valve and then figure out if my MC has a built in residual pressure valve and if so, eliminate my in-line valve. Well, depending on the answer to my question in paragraph one.

You would need a 2# residual pressure valve when the MC is lower than the calipers to prevent backflow.  But you still need one to keep pressure on the rear drums as they don't move as fast as calipers.  Without it the brakes will not feel right.  For this you need a 10# valve.  If ever you swap the rear drums for disc, then you can remove that valve completely.

Now that I think of it, you CAN have two residual pressure valves in line, I was thinking about something else.

Anyway, if your MC is for a disc brake car then it won't have the valve.  It's only on drum MC's.  You could look up the specs but I doubt it has one.  I have the 70 disc MC and it does not have that valve.  But no harm anyway if you have two!  don't know why I got so confused on that before, I have to tell these people here to stop giving me work and interfere with my DC time!   

So yes, all you need is to replace the distribution block with a combo valve and you'll be set.  If someone can confirm that the one I posted is a direct swap for the block (without having to redo the brake lines) then I'm getting one myself.

[Musicman]

Older MC's for Drum Brake vehicles had residual pressure valves built into the outlets... New, Rebuilt or re-pop units do not.
Yes, you can have 2 valves in the same line, it won't hurt a thing.
2 psi valves are used in situations where the MC is below the calipers or drums, typically Hot Rods, etc, to prevent gravity draining the system back through the MC.

Metering (Hold Off) valves are used in systems with rear drums and front disc's. The Metering valve holds off the engagement of the front disc's until after the rear drums have been engaged. Once the rear brake shoes have made contact with the drums, pressure builds in the system, which opens the Metering Valve, supplying fluid flow and pressure to the front calipers.

[bull]

Ok, the redundant rear residual valve being a problem didn't make any sense. I equated it to having two check valves in an air line. Anyway, thanks for clarifying.

Now, one last time to clarify regarding metering valves (all this verbiage is getting difficult to wade through). Since a combination valve would have an integrated metering valve a combination valve is all I need, correct? No seperate metering valve (as shown in my third graphic above) should be required.

[b5blue]

  Bull I've been following this for some time as I'm going to be doing the swap out, from 10" drum to 11 3/4 disk with a manual master myself. It was my understanding the adjustable proportioning valve was all that was needed and the residual valve was not needed, all it did was hold the drum brake slave cylinder's cups tight to the bore.
  By restricting the flow to the rear drums the adjustable prop. valve "meters" the flow of brake fluid. The small steel disk in the remaining rear drum slave cylinder that is "standard" now eliminated the need for residual pressure as it holds the rubber cup seal tight. (So if you have it still built in to the master, you remove it.)
  I found Wayne on eBay looking for a correct manual master cylinder and he was very knowledgeable on all aspects of Mopar brakes as that is his specialty. I'd get in contact with him to get his take on all this before buying and installing. http://www.theramman.com/
  I'm going to re-read: http://www.moparaction.com/Tech/archive/disc-main.html for the 10th time as I don't recall all this stuff being needed....     

[bull]

Yeah, I'm a little disappointed with the Mopar Action article when it comes to the small details. It really doesn't tell you much other than what larger componants are used.

[b5blue]

I just re-read the whole thing, it covers this. http://www.moparaction.com/Tech/archive/disc-main.html (If Rick is right, and by now he'd updated/corrected if needed.)    I won't know till I swap! 

[bull]

I just re-read the whole thing, it covers this. http://www.moparaction.com/Tech/archive/disc-main.html (If Rick is right, and by now he'd updated/corrected if needed.)    I won't know till I swap! 

I reread it again too and saw this (again): "Some factory installations, notably C-body and later B-body cars, used a "combination" valve, which also included a front-brake metering valve. Its function was a allow the rear brakes to achieve some minimal line pressure (against the return springs) before the fronts began to apply. This was supposed to reduce the possibility of the fronts locking up first on glare ice. Don't worry about this, besides, with the rears locked first, the car must spin. In addition, none of these valves are no longer available new, repops are from who-knows-where, and most available junkyard samples all seem to be made of cast iron (instead of brass) so they're rust city. Again, your best bet is to just leave your stock "tee / switch" assembly unmolested and plumb in an adjustable valve in the rear line, as we've done in our swap."

So unless I'm comprehending it wrong, he seems to say what I did will work. "...leave your stock "tee / switch" assembly unmolested and plumb in an adjustable valve in the rear line."

[b5blue]

That's my take on it. 

[bull]

That's my take on it. 

But what I did doesn't work.

[elacruze]

Why do you think you need a proportioning valve?

[bull]

Why do you think you need a proportioning valve?

To balance the brakes so I don't have either the backs or the fronts doing all the work. Right now it's adjusted so that if the system were working right the front should have roughly 60%-70% of the braking power but it's probably about 40% to the front. With the valve opened completely (proportioning basically taken out of the system) the rears lock up fast and hard. When I say "opened" I'm assuming that with the prop valve open there is no restriction to the rear lines. I would think these valves would work the same as a faucet where righty-tighty closes it off I'm not sure that's the case. Either way, when I turn it to the opposite extreme from where it's at now the rears lock up bad.

[Musicman]

Its function was a allow the rear brakes to achieve some minimal line pressure (against the return springs) before the fronts began to apply. This was supposed to reduce the possibility of the fronts locking up first on glare ice. Don’t worry about this, besides, with the rears locked first, the car must spin. In addition, none of these valves are no longer available new, repops are from who-knows-where, and most available junkyard samples all seem to be made of cast iron (instead of brass) so they’re rust city. Again, your best bet is to just leave your stock “tee / switch” assembly unmolested and plumb in an adjustable valve in the rear line, as we’ve done in our swap."

The person who wrote this should stick to writing about stuff they know about, and not brake components. 

[b5blue]

That's my take on it. 

But what I did doesn't work.

Have you a Disk type master? 

[bull]

That's my take on it.  

But what I did doesn't work.

Have you a Disk type master?  

Yes.

I'm going to try replacing my distribution valve (or "tee/switch" assembly as it's called in the MA article) with a combination valve and see what that does.

[Musicman]

With Disc's front and Drums rear, you'll need a PV2 style Combination Valve. (combination Metering Valve, Hyd Safety Switch, Proportioning Valve)
A 10 psi residual valve for the rear line would be a plus, if you don't already have one.