disc brake swap problem
Thread Starter
1st Gear Member
Joined: Dec 2007
Posts: 129
From: Lake Forest, CA
disc brake swap problem
i have no idea what this is for or where it is put, the instructions for the whole thing sucks...literally. anyone want to help me out? i wish they had instructions for visual learners haha.
6th Gear Member
Joined: Dec 2005
Posts: 5,212
From: Hills of California
that thingy balances pressure between front and rear brakes.
We have to have more pressure on the front disc and less pressure on the rears because of weight distribution...This thingy allows us to have the front wheels lock up just an instant before the rear wheels.
it goes into the master cylinder on the rear brake line and then the rear brake line screws into the other end.
adjust in empty parking lot.
-Gun
We have to have more pressure on the front disc and less pressure on the rears because of weight distribution...This thingy allows us to have the front wheels lock up just an instant before the rear wheels.
it goes into the master cylinder on the rear brake line and then the rear brake line screws into the other end.
adjust in empty parking lot.
-Gun
6th Gear Member
Joined: Jan 2007
Posts: 5,469
From: AR
I guess that came with the kit?
There are a couple of different styles of adjustable proportioning valves. That one appears to be the style that works with a single master cylinder only.
Which brings me to a question that will effect all of my answers to you...
What year is your Mustang, and the real question, how many brake lines exit your master cylinder, one or two...
By looking at the prop. valve I am guessing just one.
That valve will have one inlet. This will come from your master cylinder.
The valve will have two outlets, the valve with the off red anodized fitting will go to the back brakes. The other outlet will service your new front brakes.
The little red thing is a residual pressure valve (RPV) that keeps the rear drum brakes in a position to apply quickly and firmly. If you are running rear disk brakes, do not use the red RPV.
So,
connect the inlet to your M/C
connect the red RPV to the line servicing the back brakes
connect the unseen port to the line servicing the front brakes
Perhaps you will be fortunate and have all of the brake line plumbing you need,,, but I doubt it.. don't be discouraged though, you will go through a steep learning curve on I/F fittings etc!! (Inverted Flare)
I recommend buying a tubing bender and an inverted flare tool, a little extra line to practice on, and a hand full of fittings... It sucks, but it can be done!
As stated the prop. valve is for setting the bias between the front and rear brakes. I have heard that one is often not needed on Mustangs, and I have heard that from the factory early dick brake equipped Mustangs did not use a prop valve.
As I said earlier, you will likely have a M/C with only one line exiting the device. This being the case, it is often recommended to replace the single M/C with a dual M/C for the sake of safety. (With a dual M/C, if the front or rear brakes fail, you still have the other, not so with a single M/C). Since you are making the conversion to front disk brakes, and if you intend on installing the prop. valve, you will be doing some brake line plumbing anyway, now is the time to make this change to a dual M/C.
If you have a dual m/c, that prop valve will not work unless there are two inlets and two outlets... if this is the case, most of what I have written here is a wast of time!!
, and you will have to get back with me...
There are a couple of different styles of adjustable proportioning valves. That one appears to be the style that works with a single master cylinder only.
Which brings me to a question that will effect all of my answers to you...
What year is your Mustang, and the real question, how many brake lines exit your master cylinder, one or two...
By looking at the prop. valve I am guessing just one.
That valve will have one inlet. This will come from your master cylinder.
The valve will have two outlets, the valve with the off red anodized fitting will go to the back brakes. The other outlet will service your new front brakes.
The little red thing is a residual pressure valve (RPV) that keeps the rear drum brakes in a position to apply quickly and firmly. If you are running rear disk brakes, do not use the red RPV.
So,
connect the inlet to your M/C
connect the red RPV to the line servicing the back brakes
connect the unseen port to the line servicing the front brakes
Perhaps you will be fortunate and have all of the brake line plumbing you need,,, but I doubt it.. don't be discouraged though, you will go through a steep learning curve on I/F fittings etc!! (Inverted Flare)
I recommend buying a tubing bender and an inverted flare tool, a little extra line to practice on, and a hand full of fittings... It sucks, but it can be done!
As stated the prop. valve is for setting the bias between the front and rear brakes. I have heard that one is often not needed on Mustangs, and I have heard that from the factory early dick brake equipped Mustangs did not use a prop valve.
As I said earlier, you will likely have a M/C with only one line exiting the device. This being the case, it is often recommended to replace the single M/C with a dual M/C for the sake of safety. (With a dual M/C, if the front or rear brakes fail, you still have the other, not so with a single M/C). Since you are making the conversion to front disk brakes, and if you intend on installing the prop. valve, you will be doing some brake line plumbing anyway, now is the time to make this change to a dual M/C.
If you have a dual m/c, that prop valve will not work unless there are two inlets and two outlets... if this is the case, most of what I have written here is a wast of time!!
, and you will have to get back with me...
Last edited by JMD; Sep 12, 2008 at 12:08 AM. Reason: typo
6th Gear Member
Joined: Oct 2006
Posts: 6,417
From: Cork, Ireland
hiya ...
just a few additions top that. did the swap 2 months ago.
there's 2 pieces (the black proportioning valve) and the red pipe (residual pressure switch)
If you are having discs in the back, then do not mount that red pipe. It's only for rear drums. It is for preloading the drums (it keeps a constant (little) pressure on the back lines). the black thing you will always need, as above mentioned you can regulate the pressure on the back with this.
I'll explain again how to hook it up, even though JMD already said it. but if you read 2 descriptions it might be easier to understand
the new master cylinder in the kit has 2 outlets. The one near firewall is for the front of brake system (the discs). The other outlet forward of the MC is for the rear only.
From the outlet of the MC serving the front discs (it's the one closer to firewall), plumb the following:
MC->distribution block (that is just a 4 way distributor that was already there before you started the swap).
From the distribution block you need 2 outlets going to the front disc brakes. one each.
As your original distribution block usually has 4 connections you need to plug (close) the one that is then not used anymore.
So on the distribution block you should have only connected the firewall near port of MC and both front brakes. all other connections on it (if there are) need to be blocked.
If there is a line going from distribution block to rear brakes, remove it from the block and plug the hole.
Once you have the front done, do the rear. this needs to go as follows:
MC the forward port for rear brakes connects to the proportioningvalve, to this you hook up directly the residual pressure switch as in picture. from there you go to the original rear lines. The distributor for the 2 rear brakes is still the original one in theback over the rear axle, so there is only this one line going to the back ...
I'll paint a picture of it at some stage ...
Kalli
just a few additions top that. did the swap 2 months ago.
there's 2 pieces (the black proportioning valve) and the red pipe (residual pressure switch)
If you are having discs in the back, then do not mount that red pipe. It's only for rear drums. It is for preloading the drums (it keeps a constant (little) pressure on the back lines). the black thing you will always need, as above mentioned you can regulate the pressure on the back with this.
I'll explain again how to hook it up, even though JMD already said it. but if you read 2 descriptions it might be easier to understand
the new master cylinder in the kit has 2 outlets. The one near firewall is for the front of brake system (the discs). The other outlet forward of the MC is for the rear only.
From the outlet of the MC serving the front discs (it's the one closer to firewall), plumb the following:
MC->distribution block (that is just a 4 way distributor that was already there before you started the swap).
From the distribution block you need 2 outlets going to the front disc brakes. one each.
As your original distribution block usually has 4 connections you need to plug (close) the one that is then not used anymore.
So on the distribution block you should have only connected the firewall near port of MC and both front brakes. all other connections on it (if there are) need to be blocked.
If there is a line going from distribution block to rear brakes, remove it from the block and plug the hole.
Once you have the front done, do the rear. this needs to go as follows:
MC the forward port for rear brakes connects to the proportioningvalve, to this you hook up directly the residual pressure switch as in picture. from there you go to the original rear lines. The distributor for the 2 rear brakes is still the original one in theback over the rear axle, so there is only this one line going to the back ...
I'll paint a picture of it at some stage ...
Kalli
6th Gear Member
Joined: Oct 2006
Posts: 6,417
From: Cork, Ireland
just a quick scribble ... hope it will help. if you had originally only one line from master to distribution block, then the new setup has one line going to distribution block and the rear gets it's own line. so therefore rear is not hooked to distribution block anymore. There is a plug with the kit you can screw in the distribution block.
3rd Gear Member
Joined: Apr 2008
Posts: 939
From:
The black piece is NOT a proportioning valve. Do a google search, and you'll see what a proportioning valve really is. It's a bit more complicated than a simple valve with a **** on it.
The black piece is just a pressure reduction valve. As said above, you need to lock up the fronts before the rears. Otherwise the rear becomes the front, and that's a bad thing. The black vlave allows you to decrease the braking pressure applied to the rear to make that adjustment.
A true proportioning valve would be slightly better. But you might have trouble finding one with the right balance.
The red piece is a residual pressure valve. It's not a switch. In some cars the MC is mounted lower than the brake caliper. That would allow fluid to flow back to the MC from the caliper. The valve prevents this. If the MC is in the stock Mustang position, you don't need it. It won't hurt anything to install it though.
You should use a good teflon paste thread sealant on any NPT threads. But the flare fittings don't need it.
The black piece is just a pressure reduction valve. As said above, you need to lock up the fronts before the rears. Otherwise the rear becomes the front, and that's a bad thing. The black vlave allows you to decrease the braking pressure applied to the rear to make that adjustment.
A true proportioning valve would be slightly better. But you might have trouble finding one with the right balance.
The red piece is a residual pressure valve. It's not a switch. In some cars the MC is mounted lower than the brake caliper. That would allow fluid to flow back to the MC from the caliper. The valve prevents this. If the MC is in the stock Mustang position, you don't need it. It won't hurt anything to install it though.
You should use a good teflon paste thread sealant on any NPT threads. But the flare fittings don't need it.
