1970 base Cougar another problem trying to fix brakes

This car is originally a 4 wheel drum car. Someone put front disc Wilwood conversion on.

Front brakes dragging when you release pedal

Narrowed it down to wrong or bad master and or proportioning valve

Someone also put a booster on but not a cougar booster it is a 6 inch diameter booster gold in color. I believe reason for smaller booster is they also put on a Modern driveline hydraulic clutch system on it. A normal 8 or 9 in diameter cougar booster hits the clutch master

Bought new master but does not fit on booster. Holes on booster farther apart than on new master. I have no idea what kind of booster they put on. They had cut open the mounting holes on their master so it would somewhat fit the booster

My question:
Does anyone know of a 6 inch diameter power brake booster and master combination that I could use for this application???

Thanks.

Sorry. Remeasured the booster. It is a 7 inch diameter booster.

The best booster would be a rebuilt original. But WCCC offers a repro that does not require a core exchange:

Brake Booster - Power - Bendix Style - Repro ~ 1970 Mercury Cougar / 1970 Ford Mustang ( 1970 Mercury Cougar, 1970 Ford Mustang ) at West Coast Classic Cougar :: The Definitive 1967 - 1973 Mercury Cougar Parts Source

And this master cylinder is the one I used, although it only lasted 12 years:

Master Cylinder - Disc - Power Brake - PREMIUM - Repro ~ 1967 - 1972 Mercury Cougar / 1967 - 1972 Ford Mustang ( 1967 Mercury Cougar, 1968 Mercury Cougar, 1969 Mercury Cougar, 1970 Mercury Cougar, 1971 Mercury Cougar, 1972 Mercury Cougar, 1967 Ford Mustang, 1968 Ford Mustang, 1969 Ford Mustang, 1970 Ford Mustang, 1971 Ford Mustang, 1972 Ford Mustang ) at West Coast Classic Cougar :: The Definitive 1967 - 1973 Mercury Cougar Parts Source

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Calicat I would love to be able to use that setup but the booster is 9 inches in diameter.

Because of where the hydraulic clutch master cylinder is mounted I can only get a 7 inch in diameter booster into the space.

I think they put a universal booster on it but have no idea the make.

Thanks.

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Wilwood has a tech support line, might be worth seeing what they might offer for a solution to master cylinder/ booster. I think they used to run some disc kits without a booster.

Thanks. I’ll give that a try!!

I’ve used a lot of these master cylinders and they always work perfectly. I know you have a 1970 but they still ought to do the job.

Glad to hear that - I just got one from them. Here is the one for the 70 models with the embossed lid rather than the sticker:

1969-72 Mustang & Shelby Master Cylinder with Cap | Dead Nuts On

The problem I’m having is with the booster. No idea what booster they put on but the two bolts on the booster are farther apart than the holes on any master I have seen that is for the 1970.

To make the master that is on it now fit they cut a slot out of each hole on the master

The booster is likely crap. You need the reproduction booster or the real one.

The master cylinder from Dead Nuts on looks good. I didn’t know about those but now I do!

Thanks Royce.

Problem is the original boosters are 8 and 9 inches in diameter.

Do to someone putting a hydraulic clutch in this car the clutch master is in the way of an original booster fitting. I can’t have a booster bigger than 7 inches in diameter.

I can’t speak about a hydro boost as I haven’t used one.

My ā€˜67 has a Hydra boost. Engine has a CVF serpentine belt system along with a hydra boost pump that powers both brakes and Flaming River Rack & Pinion. There was/were some issues in arranging the plumbing and keeping it neat and organized.

It’s actually going to move under it’s own power in at least 7 years this week. From the shop to the enclosed trailer to heated winter storage.

I plan to video it.

Testing will begin in mid to late April and will report when I get behind the wheel.

Ron

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Is it possible that Wilwood provided the smaller diameter booster as part of a kit?

Randy Goodling

CCOA #95

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Randy.

I don’t believe Wilwood handles any boosters. Just masters.

Amazon lists ā€œWilwood typeā€ 9ā€ boosters - Amazon.com

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It’s likely that the adjustment between the master and booster is too tight, causing the compensation port in the master to be covered when the brakes are released. If you have a threaded adjustment on the master, back it off in half turns until it’s resolved. This diagnosis can be verified before making adjustments by opening a bleeder port in the caliper and see if fluid jumps out and the wheel immediately frees up

If the test suggested by e clone works you can back off the mounting nuts that hold the master to the booster …install a body shim in-between the two ans snug up….check pedal…repeat as necessary adding a shim to each ear. The amount af shim will tell you how much you need to shorten the push rod

Problem is the master is leaking and has leaked into the booster. So both need to be changed.

But because of the location of the clutch master I can’t fit the original 8or 9 inch booster in the spot.

The booster can’t be more than 7 inches in diameter.

I think I would contact Wilwood and see if the have a clutch slave that is compatible with the stock booster. Because Mustang is the same I would be shocked if they did not have a solution.