Replacing Old M/C with Dual M/C w/stock brakes

Gritsngumbo · Post by **Gritsngumbo** » April 20, 2010, 2:48 pm

Question. Just determined that I need to replace the M/C on my 63 F250. Stock brakes and I hate to replace with the single pot, so if I replace with a dual chamber M/C do I have to re-plumb the lines, or can I have both lines from the M/C merge into the original brake line?

PFM-64f100 · Post by **PFM-64f100** » April 20, 2010, 2:52 pm

re-plumb the lines. the reason for going to Dual M/C is if one set (Front or Rear) fails then you have the second to stop you. Keeping it all on one line or merged line defets the purpose of a Dual M/C...

Gritsngumbo · Post by **Gritsngumbo** » April 20, 2010, 2:56 pm

Duh!
Crap! I knew that. Just couldn't retrieve it from my memory cache. (That's my latest excuse for not remembering things.)

62galxe · Post by **62galxe** » April 20, 2010, 4:47 pm

you could use the other hole for the brake switch.

slickmainer · Post by **slickmainer** » April 20, 2010, 5:48 pm

hmm never thought of that.

Gritsngumbo · Post by **Gritsngumbo** » April 20, 2010, 6:00 pm

Nor I! Good idea. Since the price for both is about the same, if I go ahead with the dual them I won't have to replace it when I get around to running new lines.

Hawkrod · Post by **Hawkrod** » April 20, 2010, 6:17 pm

You don't have to run new lines for a dual MC, All you need is a short piece of line, a coupler and a plug. On mine, I just removed the line to teh rear axle from the junction block and plugged the hole with a tubing plug (parts stores have them in teh boxes that they have adapters in). Then put a coupler on the line and attach a short piece of line to go up to the master cyliner. Reattach the old line to the rear half of the MC and hook the new line to the rear brakes to the front half of the MC. It is quick and easy to do. For a brake switch I put a T off of the MC on the line to the rear. Hawkrod

Here is a picture of my 62 Tbird (it is pretty much the exact same situation!) which I put a 72 F100 MC on:

62galxe · Post by **62galxe** » April 20, 2010, 6:24 pm

my brake switch solution. 68 mustang master required no pushrod modifications.

ProStreet66 · Post by **ProStreet66** » April 20, 2010, 8:05 pm

Do you guys know what the plate is between the master cylinder and firewall? Is that something I can make? If so how thick is it?

Gritsngumbo · Post by **Gritsngumbo** » April 20, 2010, 8:35 pm

Thanks guys! As always, several innovative ideas to choose from

Post by **Greg D** » April 21, 2010, 12:04 am

If the rest of your lines are in good shape splitting the F/R is easy.
Remove the 4 way block just behind the crossmember in the frame. You will need 1 double female connector and one 3 way block (or plug the rear side of the 4 way) then run the 2 lines up to the MC. Front brakes go to the port closest to the firewall - rears to the front. It takes longer to bleed the system than do the conversion. The 68 Mustang MC will bolt right in. You can use another 3 way for the pressure switch as shown, make a small bracket for a plunger style like Jason (JWH F100) did, or use a Mustang pedal switch although adjusting the last one can be a tad tricky (you have to install it backwards with an extra washer or the contacts will ground on the pedal hanger) but it will work.
Do yourself a favor Gerald - split the system.

Garbz · Post by **Garbz** » April 21, 2010, 12:44 am

ProStreet66 wrote:Do you guys know what the plate is between the master cylinder and firewall? Is that something I can make? If so how thick is it?

The plate is 61 to 64 only. It adapts the master to the early bolt pattern for boosters. 65 up uses the modern pattern for boosters and the master bolts directly to the firewall.

Garbz

Alan Mclennan · Post by **Alan Mclennan** » April 21, 2010, 3:42 am

I`m with Greg!, why would you install a dual MC and just hook up one cylinder?, bit like putting both feet in one leg of your undies!

Gritsngumbo · Post by **Gritsngumbo** » April 21, 2010, 8:09 am

Alan Mclennan wrote:I`m with Greg!, why would you install a dual MC and just hook up one cylinder?, bit like putting both feet in one leg of your undies!

Oh, never fear...I was reminded of the "why not" in the first answer to my question. As always, some innovative solutions from the members. As far as this truck, since it's seldom driven (mostly need brakes to move from point A to point B without running over something), I'm going to replace the M/C with a single pot since it's easy and quick and only $15. I'll probably use Greg's idea for splitting the lines to put discs on my Uni.
BTW: At my age, I'm doing good to get one leg in my undies without falling on my arse (Note the Australian spelling).

slickmainer · Post by **slickmainer** » April 21, 2010, 8:23 am

what diameter is standard brake lines for our truck? 3/8s? Also is one tool better than another for bending lines and double flaring them? I assume a cutter is a cutter, but some of the bending tools i see in Napa look a little weak?

charliemccraney · Post by **charliemccraney** » April 21, 2010, 8:45 am

ProStreet66 wrote:Do you guys know what the plate is between the master cylinder and firewall? Is that something I can make? If so how thick is it?

Of course you can make it. It is 1/4" thick. 4 holes for mounting to the firewall, 2 countersunk holes for the bolts which hold the mc, and 1 big hole for the pushrod. It can all be done on a home drill press. If you really want to get fancy, you can clearance the back to clear a knock out on the firewall and allow it to sit flat against the firewall. The stock plate doesn't take it into account.

Gritsngumbo · Post by **Gritsngumbo** » April 21, 2010, 8:49 am

charliemccraney wrote:
ProStreet66 wrote:Do you guys know what the plate is between the master cylinder and firewall? Is that something I can make? If so how thick is it?
Of course you can make it. It is 1/4" thick. 4 holes for mounting to the firewall, 2 countersunk holes for the bolts which hold the mc, and 1 big hole for the pushrod. It can all be done on a home drill press. If you really want to get fancy, you can clearance the back to clear a knock out on the firewall and allow it to sit flat against the firewall. The stock plate doesn't take it into account.

Couldn't you just take one off another truck? Or are they generally too rusty to be of value?

charliemccraney · Post by **charliemccraney** » April 21, 2010, 9:04 am

Gritsngumbo wrote: Couldn't you just take one off another truck? Or are they generally too rusty to be of value?

Yeah but that would be easy.

I had to make one because I'm using a GM mc. No reason other than it fit the disc brake kit manufacturer's mc size recommendations and it allows plenty of room to remove the valve covers. It's the only one I could find that satisfied the requirements.

Gritsngumbo · Post by **Gritsngumbo** » April 21, 2010, 9:12 am

charliemccraney wrote:
Gritsngumbo wrote: Couldn't you just take one off another truck? Or are they generally too rusty to be of value?
Yeah but that would be easy.
I had to make one because I'm using a GM mc. No reason other than it fit the disc brake kit manufacturer's mc size recommendations and it allows plenty of room to remove the valve covers. It's the only one I could find that satisfied the requirements.

Charlie: Do you have a booster? Is that why there's a clearance issue with the VC's?

charliemccraney · Post by **charliemccraney** » April 21, 2010, 9:38 am

No booster. Though it doesn't look like there's much room for a booster.

The people who supplied the brake kit recommended a 1 1/8" bore mc. I have no idea why the recommend that for manual brakes but they did. At first I was using one, I think from a 70s Lincoln with the ports pointing toward the engine. With the Ys stock stamped steel covers, there was barely enough room to remove the valve covers. I'm using taller cast covers on the newer engine and there wouldn't have been enough room to remove them with that mc. I tried to find a Ford product mc with 1 1/8" bore and ports pointing away from the engine but could find nothing. A GM unit satisfied the requirements but the bolt spacing is different. Rather than grinding the master cylinder to fit, I made a new adapter so that it will bolt on. This way, any emergency roadside repairs will be easy.
Now I'm running a 1" bore. Since I had the GM adapter in place and have no idea where I put the original, I used another GM mc. There are plenty of 1" bore Ford mc's that would work. I didn't have a problem locking the brakes with the 1 1/8" bore but the 1" is so much nicer.

This is the back side of it.