Disc brake conversion

[melo-yelo]

I have read the Falcon forum trying to find the answer to my question but could not. I do not see a proportioning valve listed on the list of parts used to install the Scarebird conversion. I have everything completed on my Scarebird conversion now except plumbing. I'm useing a 1967 Mustang manual disc/drum master cylinder, do I need a proportioning valve?

[Luva65wagon]

I didn't use one on my wagon and it works perfect. Nothing scary hard to push or out of balance. When I locked up the wheels during my test the skid marks where just where I'd have wanted them to be. Compared to the old brakes, it's very safe and straight even with the hands off the wheel.

I had done the dual MC 10 years ago, so I can't recall whether I did the drum/drum MC or not (scarebird wasn't in my vocabulary at the time). One of these days I plan to pull out the MC and rebuild it just to see what diameter the two stages are once and for all.

We also did Gary's 63 and I think he did the disc/drum MC (whatever was on the parts list) and he wasn't happy with the foot pressure required. He didn't add a P_Valve then either.

[MacDee]

Yeah, I used a disc/drum master cylinder and no proportioning valve. At least the disc/drum MC is what I ordered. Considering the quality of the NAPA store where I bought it, who knows what I actually got!

I really don't even know what a "proportining valve" is! Theoretically, a "valve" would not be able to adjust the front-to-back line pressure proportion, at least I can't see how it could. I have searched for reliable information on "proportioning valves" and have only uncovered a device that MEASURES the pressure differential between the two independent systems. It has a switch that turns on a warning light when one system has lost pressure. If this is the device commonly referred to as a "proportioning valve", it is really more of a "proportion sensor".

I still have to push the pedal pretty hard to stop the car, but I don't know if it is UNUSUALLY hard. Disc brakes do not have the "self-actuation" feature most drum brake setups have, so I would expect to need to press the pedal pretty hard on an un-boosted disc brake setup. Roger, someday you'll have to drive my car to see what you think. I can only compare to my late-model Mazdas with boosted brakes. I really like the disc brakes, though. I get safe, secure stops with no fade. Very much unlike the old drums...

[Nathan289]

I used a 74 Maverick Master cylinder no porportioning valve..
While pedal travel is farther than I'd like, everything works extremly well.
My plans are to play with mcs till I find the desired pedal travel..

Nathan

[melo-yelo]

I think I will try going with out the valve for now and see how it works. One friend has a 68 mustang and I asked him if his has a valve and he said no, but then I'm not sure if he knows what i'm talking about(not to much of a mechanic). Again thanks for the information.

[Nathan289]

I'm running two different falcons with disc brake set up neither one have a valve and both stop fine..
My 61 is 4 wheel disc brakes and uses a corvette mc with a pedal rod from a 67 mustang drum brake set up.. works awesome stops like a dream. I think it stops better than some new cars..this is a granada/crown vic swap.
the 62 ranchero is disc/drum using the scarebird set up.. stops great, but the pedal travel is more than I like.. I just need to find a better master cylinder.

I think you will find that the valve isn't needed..

Nathan

[melo-yelo]

I have my hubs fitted to the brake rotors and the new studs installed. My concern is that the bolt pattern in the rotors seems to be a slight bit different than the stock falcon hubs, the rotors don't slide on and off the hub easily. Was this a concern for any one else doing the scarebird conversion ?

[Nathan289]

I used the orginal falcon hubs and turned them down on a brake lathe to get them to fit inside the 89 nissan stanza rotors.
I had no fitment issue.

I also pressed the new wheel studs in with the rotors on the hub.. Its more like I pulled them into the hub.. I used a spacer and a lug nut to hold the stud in place.. I did this to all 4 studs. I then would press them from the backside.

I'm thinking maybe you have a couple of studs that arent pressed in straight??

Nathan

[Luva65wagon]

Both I've done have been stock hubs. No problem with these on the Nissan rotors.

[Jerry Alfaro]

I have read the Falcon forum trying to find the answer to my question but could not. I do not see a proportioning valve listed on the list of parts used to install the Scarebird conversion. I have everything completed on my Scarebird conversion now except plumbing. I'm useing a 1967 Mustang manual disc/drum master cylinder, do I need a proportioning valve?

I did a disk brake conversion on my 65 Ranchero and it works sweet with the Welwood proportioning valve.

http://www.rainierfalcons.com/forums/showthread.php?t=341

The link shows some of the pictures of the conversion.

jerry-

[melo-yelo]

I have every thing done now and waiting for spacers to come because my 14" wheels will not clear the calipers. I have much better brake pedal feel now. Can't wait to actually get the wheels back on and take for a test drive. Thanks to everyone for the information.

[Luva65wagon]

Ah... so you needed spacers too! I don't know how Gary got away without them. I have spacers now, but have yet to put them on. What I did at that moment (when I assembled all this summer before last) was to measure the thickness of a lot of washers to make stacks of three per stud to give me the clearance. Cheap, but it worked. So I'll be putting on my real spacers when it warms up out there in my garage....

Let us know how it goes (or doesn't depending on how you look at it)... and did you install a PP valve or no?

[melo-yelo]

Ah... so you needed spacers too! I don't know how Gary got away without them. I have spacers now, but have yet to put them on. What I did at that moment (when I assembled all this summer before last) was to measure the thickness of a lot of washers to make stacks of three per stud to give me the clearance. Cheap, but it worked. So I'll be putting on my real spacers when it warms up out there in my garage....

Let us know how it goes (or doesn't depending on how you look at it)... and did you install a PP valve or no?

I decided to try it with out the valve. I'm very happy with brake pedal feel. I'm hopefull that it stops fine with out the valve. I ran all new front brake lines and used the old rear ones for now, if it stops ok I'll run new rear brake lines, if not I'll plumb the new rear lines to include the valve. Maybe i'll just plumb in a valve either way, I like the looks of no valve, it looks clean under the hood. Hope the spacers I ordered arrive today so I can test drive it.