residual pressure valve

[agent orange]

Ok, i just realized that the large thing that the brake line screwed into on my old master cylinder was a residual pressure valve to keep pressure on my rear drums. Hopefully the trash hasnt been taken out since the i threw out the old MC! My question is, is this something that i can find in a parts store or dealership if i cant find my old one? Do i really need a residual pressure valve? Is this why i cant lock up my brakes with my current setup (i assumed it was the hundred pounds of wheel and tire im running, or a sign i needed to bleed again)?

Matt

 

[Dynosoar]

Most race car supply places (kartek, summit etc..) sell an inline valve that you can splice in. They are realativly inexpensive (around $20.00 bucks), but you have to cut the line and reflair the tubing. or get a pressure valve from a 60 and put it in. I will try and post a pic of mine latter.

Dynosoar

 

[agent orange]

Ok, so is this valve included in the lspv (what does that stand for anyways) or is it threaded into the master cylinder? Just realized the reason i tossed the old MC and disregarded the big black cylinder things that the lines screwed into was that they were on the front and the rear of the MC, i guess i might have my stuff installed right as it is.

 

[Dynosoar]

LSPV (Load Sensing Proportioning Valve) 60's don't have a LSPV only 62's. The residual pressure valves I have seen have been part of the distributor block (the thing that sends the fluid to the correct locaton (eg front or rear) I have also seen them as part of the master.

Dynosoar

 

[agent orange]

Hmm, i only have the two brake lines running to my master cylinder, no junction block. There were these like one inch circular jobbies that were threaded into the ports on the master cylinder that the brake lines in turn would thread into, but i remember there being two of those not one. Is it possible that my residual proportioning valve was eliminated when a shop replaced my MC a few years back? If so, are there proportioning valves that incorporate the residual pressure aspect? If im having to cut and splice into the lines i may as well add a proportioning valve. If i were to do that, should i take out the lspv?

Seriously, why do projects like this have to snowball so fast?

Matt

 

[agent orange]

Ok, i was looking at residual proportioning valves on various sites, and i have a couple questions. With the lspv setup as it is, would the residual pressure valve go directly after the rear brake side of the master cylinder, or does it go further along in the system? Im thinking it would be the most sano to put it inline and cut and reflare both sides of the brake line and use 1/8 in fittings that work with the commonly available residual pressure valves. Im assuming that i can make npt fittings work with the lines i have on truck if i flare them right, correct? Oh, what size flare am i supposed to use too? Ive never done any flaring or anything before so im just trying to not get halfway in and realize that i forgot something important.

 

[Tinker]

Practice on new tubing before you cut your own lines - old brake lines tend to be brittle sometimes.

 

[Dynosoar]

Orange don't mix up your valves. The portioning valve balances the fluid between the front and rear. The residual presure valve keeps pressure in the break line to keep the rear breaks ready to go (the springs in the drum breaks want to push all of the fluid back toward the master) In addition for safty you want to be sure you double flare the tubing when you re do it.

Dynosoar

 

[agent orange]

What exactly is involved in a double flare?I understand the distinction between proportioning valves and residual valves, i was just wondering if anyone made a proportioning valve that could be adjusted to hold some line pressure like a residual pressure valve, but couldnt find one. I guess my most pressing question is whether the rpv would go right after the master cylinder or further along in the system. Thanks for all the help dynosaur.

Matt