If your Cougar is 1967 - 1971 then the master cylinder should be ( provided it was for the disc-drum brake system original to the car, or swapped into the car from another Cougar or Mustang ) C8ZZ-2140-A. If it was a 1967 ( up to 2/6/67 ) then it could be a C7ZZ-F. In any case it should look like:
Image from Dead Nuts On website : 1969-72 Mustang & Shelby Master Cylinder with Cap | Dead Nuts On
If the master cylinder is original ( Bendix ) to the car, then it would have their 2227161 number cast into the bottom of the reservoir.
As well there is a lot of useful information about the master cylinder ( and variations ) here:
Morning, rereading my post seems the most important word got deleted during editing. Sorry.
So to clarify. The Cat is a 69 XR-7 convertible. It came with factory front disc /drum rear. Someone put a disc brake rear conversion and never finished it.
I an in search of a cast iron master cyl (not alum aftermarket) that will bolt upto the factory booster.
Keeping everything factory except the conversion to the rear axle, IE disc for all 4 wheels, thus the need for the correct master cyl for the 4 wheel disc setup/conversion now on the Cat.
Im not going back to factory, as they have most everything done cept master cyl which is the wrong one for 4 wheel disc…
So, back to the original question, does anybody have a part# that will work?
I suspect the question is not absolute size but adequacy. The area and sweep of the piston is unchanged, and the amount of absolute force is also unchanged. Effective force is changed some by the diameter of the piston in the caliper. Balancing those factors is the job of a proportioning valve. Let us know how this turns out. You certainly don’t want equal force front and back.
What is your brake setup now? Manual, power, disc front only and drum or disc on all 4s? I did a disc brake conversion on my 68 with manual front disc. Didn’t like the pedal feel, too soft for me. Went to a bigger MC and the feel is much better now. Then with an adjustable prop valve, they are perfect.
The one from WCCC marked “four wheel disc” will work fine. The size of the reservoir means you might have to refill it more often when bleeding. It matters not when you will use it.
Awsome info! Thanks to everyone. I’m in the thick of 2 convertibles, so a bit slow being able to report back results. Ill get the results soon & post.
A 70s Corvette master cylinder will work but may need the mount holes opened up a little. Definitely 1 1/16 bore and use a manual proportioning valve. Several manufacturers use the same one. Summit or Jegs may have a cheaper house brand one. With the proportioning valve you can dial in rear brake bias and keep from having premature rear brake lock up
The master cylinder reservoir is designed to provide fluid capacity for actuating the brake pistons both initially and as the pads wear down (to metal). Using a Cougar M/C with stock capacity with rear disc brakes will work initially but as the pads wear it may not provide sufficient fluid. Of course, you could periodically top off the fluid, but can you guarantee that your customer will remember to do that every 10K miles?
Ford didn’t so they used units with greater capacity such as the taller M/C on the 1975-79 Granada/Versailles with 4-wheel disc brakes. Unfortunately that part is not usable on our cars unless you convert to the Hydro-Boost because the M/C mounting flange is tilted.
On the race cars with manual brakes, we used the M1385 M/C from a 1969 F250 - similar to the one recommended in the B302 Chassis Modification Guide. However, since it is bigger, it may not clear the shock tower.
Bottom line: Look for a taller/wider M/C than the factory unit to provide the extra reservoir volume, like a MC36440.
