Mixing and matching master cylinders.

[XplosiveLugnut]

I've got a master cylinder conundrum. The problem is the original drum/drum MC ('71 F100) has it's outlets on the driver side. The 'new' disk/drum MC from the donor truck has the outlets on the passenger side.
So I've been trying to think of a solution to this that requires little to no modification to the existing brake lines. I figure there must exist a compatible MC with the outlets on the driver side.

Lo and behold, the power disk/drum MC from a '68 Mustang does have the outlets on the driver side. This is just the first possible solution I've come across, so I figured I'd hop on here, pitch my scheme, and get some opinions.

A few details need addressing:

It has two different sized outlets, I can't check right now but I'm pretty sure the '71's got identically sized outlets. So I'm guessing a adapter or two on the fittings will be needed.

I'm also sure the Mustang has much smaller calipers and therefor doesn't need as much fluid to actuate the piston. So the master cylinder might have too small a bore to support the larger pistoned F150 calipers.

I'm also just assuming the Mustang's (or any Ford) MC will mount up to the donor F150's vacuum booster. (The donor was a 75 or later by the way)

If anyone's got a better solution or experience with this, I'd love to hear it. In the mean time I'll be searching for other options besides the Mustang's MC. Maybe there's even an aftermarket MC that'll fit the bill.

Thanks!
-Evan

***
Edit:
***

Ok, forget my Mustang non-sense. I may have found my solution. The bumpside F250s and 350s had front disks standard later on right? The master cylinders on those have the outlets on the driver side. I figure if the F350's MC bolts right in, it would be the best choice since it's for the heaviest duty truck. Guessing they probably don't differ though.

So does that sound like a plan?

Thanks!
-Evan

***
Edit: Once More
***

I'm looking at this particular product. http://shop.advanceautoparts.com/webapp ... fragment-2
Should work I guess. I know nothing of master cylinder manufacturers. Cardone appears to be an exceptional one.

And just for clarification, the first (primary?) outlet, the one with the larger portion of the reservoir, is for the front disks right?

Thanks.. again!
-Evan

[tbone6]

The forward outlet is for the front brakes.

[ultraranger]

The MC port closest to the radiator feeds the rear brakes. The MC port closest to the firewall feeds the front brakes.



A '73-up F-350 MC will have a very large MC bore diameter --somewhere around 1-1/4" or 1-3/8". You would be better off with a MC that's around a 1.00" bore diameter. The larger the MC bore the less pedal travel you will have (firmer pedal) but at the expense of being harder to apply the brakes and it will have less output pressure. A smaller bore diameter MC will have more pedal travel but the brakes will be easier to apply and the MC will produce more output pressure to the brakes.

Quote from Wilwood brake article in Car Craft:

"A smaller master cylinder bore diameter will generate more output pressure in pounds per square inch (psi) than a larger piston version given the same amount of pedal effort. As an example, let's exert a force of 50 pounds directly to a 1-inch-diameter piston master cylinder. By calculating the area of the piston (Pi x radius x radius), we come up with an area of 0.7854 square inch. Divide the force by the area (50/0.7854) and the result is 63.66 psi of hydraulic pressure. Now let's do the same math with a 7/8-inch (0.875-inch) master cylinder (Pi x 0.4375 x 0.4375 = 0.601 square inch of area). Divide the 50 pounds of force by 0.601 and we get 83.19 psi, or a whopping 30 percent increase in line pressure. For the record, there is also a significant ratio gain from the pedal of usually around 6:1, so 50 pounds of force on the pedal quickly becomes 300 pounds of force applied to the master cylinder. If we divide 300 pounds by that same 0.601-square-inch area, we get 499 psi of line pressure with a 7/8-inch piston."

Read more: http://www.carcraft.com/techarticles/cc ... z2TJEUxX92

The Mustang MC you mention has the ports on the side you are needing them on and it also has a 1.00" bore diameter.

It's always best to use direct-connection line fittings in lieu of line adapters. It looks more professional but primarily, it means less connection points that can potentially leak. Fords use 3/16" (4.75mm) diameter hard lines. The standard inverted line fitting size for 3/16" tubing is a 3/8"-24 inverted flare nut. Ford also used specialty sized fittings for 3/16" dia. tubing that were; 7/16"-24, 1/2"-20 & 9/16"-18. You can get these fittings from Classic Tube.com. The part numbers are; ST8006, ST8007 & ST8010 respectively.

Rock Auto.com has a MC listed for a '72 F-250, pwr brakes and a 1.00" bore, with ports on the drivers side for $26.79 (new not remanufactured). DORMAN Part # M83579. I would advise against rebuilt MCs unless you'd like to change the MC out again in 6 months to a year from now.

[XplosiveLugnut]

A bit of a late reply, but I wanted to confirm that Ultraranger's suggestion to use the bump-side F-250 master cylinder for a front disk conversion on a 71 F-100 worked perfectly.

To restate the problem. The MCs from the dent side had the ports for the hard lines on the passenger side. The bump side's original MC has the ports on the driver side.

The solution was to get a bump-side era MC so the ports would be on the driver side. The MC also needed to be one meant to be boosted and be hooked up to disk/drum. This was common on bump-side F-250/350s I guess. The booster sticks the MC out a bit father so the lines have to be stretched to make it to the MC. Not to big a deal since the lines had a couple large loops bent into them.

Thanks for the help!
-Evan

[ultraranger]

Glad my advise helped you out and even more glad to hear that you finally got your brake problem sorted out.