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-   -   Residual Pressure Valve BEFORE or AFTER Prop. Valve? (http://www.hotrodders.com/forum/residual-pressure-valve-before-after-prop-valve-185964.html)

matt2491 10-13-2010 09:20 PM

Residual Pressure Valve BEFORE or AFTER Prop. Valve?
 
Do I plumb the 10# residual valve in before or after the wilwood adjustable prop valve I'm using?

I'm running a disc/drum system and know there needs to be a 10# valve in the drum circuit, but if someone could tell me where it needs to be and why, I'd really appreciate it.

Thanks,
Matt

richard stewart 3rd 10-14-2010 02:33 PM

Hi Mat! :welcome:
Welcome to Hotrodders.com. Glad to have you with us.
Click the link.
Good luck,
Rich

http://ecihotrodbrakes.com/brake_facts.html

ogre 10-14-2010 07:07 PM

residual valves are need when the mc is near or bellow the brake cyl or calipers.
they are needed to keep your pads closer to disc/drums
while it may not matter, i have always seen them and installed mine after all other valves

cucumber1949 10-14-2010 08:52 PM

Quote:

Originally Posted by ogre
residual valves are need when the mc is near or bellow the brake cyl or calipers.
they are needed to keep your pads closer to disc/drums
while it may not matter, i have always seen them and installed mine after all other valves

I'm not sure it matters either, but I have never seen them installed other than the following order - mc, residual pressure valves, other valves (such as a proportioning valve), then caliper / wheel cylinder. This is how I have them on my T. Just the opposite of how Ogre has seen them if I read his post correctly. Just goes to show ya' I guess when you're asking for advice on a public forum LOL!!

adantessr 10-14-2010 09:12 PM

Quote:

Originally Posted by cucumber1949
I'm not sure it matters either, but I have never seen them installed other than the following order - mc, residual pressure valves, other valves (such as a proportioning valve), then caliper / wheel cylinder. This is how I have them on my T. Just the opposite of how Ogre has seen them if I read his post correctly. Just goes to show ya' I guess when you're asking for advice on a public forum LOL!!

Well now I guess this means I need to go shopping for some residual pressure valves for my T-bucket . I don't think it has them and the master cyl is under the floor .

65ELCMO 10-15-2010 08:31 PM

residual valves go after the combo valve. 2 # for the front disc and 10# for rear drum.

001mustang 10-15-2010 11:23 PM

Some master cylinders have residual valves built in.
From the factory the residual valve has historically been installed in the master cylinder. The proportioning and metering valves are downstream of the residual pressure valve; cleaner install. Some after market conversion kits have residual valve downstream of the proportioning valve. I doesn't makes much difference where the residual valve is installed. Make sure your mc has no residual valve if you elect to install one.

One advantage of installing a 10# residual valve for drums is the slight pressure will help expand the wheel cylinder pistons; minimizing leaks. Another advantage of the 10# res press valve is to minimize pedal travel.

A 2# res press valve for the discs is most likely unnecessary unless mc is lower elevation than calipers. Caliper pistons tend to stay in position w/o encouragement from res check valve.

cobalt327 10-16-2010 12:09 AM

Most times the add-on residual pressure valves are located after other valves unless the valve is self contained in the MC.

001mustang 10-16-2010 06:43 AM

If your car is equipped with a differential pressure brake warning switched distribution block; the proportioning valve must be installed down stream of your distribution block.

2old2fast 10-16-2010 08:06 AM

Mine are installed directly out of the m/c then combo valve. brakes work perfect,have for 9 years &32000 miles

adantessr 10-16-2010 09:28 AM

Quote:

Originally Posted by 001mustang
One advantage of installing a 10# residual valve for drums is the slight pressure will help expand the wheel cylinder pistons; minimizing leaks. Another advantage of the 10# res press valve is to minimize pedal travel.

A 2# res press valve for the discs is most likely unnecessary unless mc is lower elevation than calipers. Caliper pistons tend to stay in position w/o encouragement from res check valve.

Okay you have talked me in to ordering a 10# for the rear and not worrying about the front discs . I have tried since I last read this thread to see if there was any difference in brake travel, and the pedal does seem to come up just a little bit higher if I hit it twice. Barely noticeable , but it is noticeable . I am all about safety and optimum braking so I'm going to place an order NOW .

matt2491 10-16-2010 11:15 AM

Thanks for all the info guys. Here's what I'm going to do: Use a 1968 Mustang disc/drum 1" bore master cylinder and add a 10# rpv and a Wilwood proportioning valve to the rear circuit. That outta cover my brake system. That will let me avoid the combination valve.

001mustang 10-16-2010 12:45 PM

Quote:

Originally Posted by matt2491
Thanks for all the info guys. Here's what I'm going to do: Use a 1968 Mustang disc/drum 1" bore master cylinder and add a 10# rpv and a Wilwood proportioning valve to the rear circuit. That outta cover my brake system. That will let me avoid the combination valve.

I would use a 68 drum/drum mc w/ internal rpv's; remove rpv from front disc mc port.

If new drum/drum mc does not have rpv you can rob one from your old mc.
a1 cardone no longer includes rpv in the cheap mc.

The drum/drum mc will fit (68 mustang). the disc/drum mc will not fit (68 mustang) w/o adapter.

001mustang 10-16-2010 03:51 PM

If you are not an expert tube bender I would consider putting proportioning valve upstream of rear flex hose. You can hide proportioning valve somewhere behind rear seat. If you run too much tube up and down and have trouble bleeding high spot, you can add a high point tee for bleeding and for PSI gauge port.

Factory cars do have up and down runs; good to minimize these air catchers and to use small diameter tubes.

I have seen too many ugly brake line bends in the engine compartments.


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