Dorman Products Part # MC 73323 fits a '66 to '71 Mustang with manual Disc Brakes and works Great with Drum Brakes on Baby Birds and does not need a Proportioning valve as it is self equalizing. The master cylinder with Power brakes Does need the proportioning valve however. Nice bolt up, however I suggest a 1/8" thick plate faced like the Original master cylinder to bolt between the new master cylinder and the firewall to stiffen the firewall when you install it and the push rod will need to be 1/4" longer then stock. You will be amazed at how well the Bird will stop still using drum brakes.


Tom

What?

Had a rear break line blow on my '74 Ranchero back in the day. Brake line rusted through and blew when I tried to make a rapid slow down to make a left turn. Had a tough time getting it stopped. Missed my turn. Would have hit anyone in front of me if there had been anyone close. Emergency brake on my T Bird could have not been much worse.

Just to add fuel to the fire, I read over on the HAMB (more than 1 post) that if your running just the stock drum/drum set up a proportioning/combo valve isn't needed.

I agree with Charlie too. After working on cars 40+ yrs when I would pull one in with a blown line, cylinder etc. you still needed a boat anchor to stop it.

Dan      Kingman Az.      86409

I put that info up for Duck to help explain the dual circuit brake system. I am running Granada manual front discs and stock rear drums on my 57 Bird. Used the Granada master cylinder and a Wilwood combo valve. I don't miss the power brakes at all, they work great. Much safer and effective over the often scary front drums. Finishing up an alternator conversion this week if I can and after the holiday it's back to finishing the 445 Survival Motorsports stroker for the 65 Galaxie.

57 Black Tbird 312/auto

Mark, all that said I hope you get your brake "problem" worked out to your satisfaction.

"The Master Cylinder"

Enjoying life at the beach in SOCAL

Haha, Mark, You said it all right there... If your braking system is borderline due to lack of maintenance or you installed it improperly and didn't check it in the first place, how can it be blamed on the dual master cylinder/dual brake system when it doesn't work properly.

One thing I learned in class (way long ago) is you can't design for "Double Jeopardy". For one example, lack of maintenance and failure of a component.

Bottom line I feel when set up properly and maintained a dual braking system is way safer than a single M?C system.

"The Master Cylinder"

Enjoying life at the beach in SOCAL

The link I posted deals with the design and operation of a typical combination valve. The dual circuit master cylinders are two separate braking systems in one master cylinder body. The weak point of the design is pedal travel related to incorrect rear drum brake adjustment and/or worn linings. If the front brakes are lost do to a hydraulic failure the pedal needs to travel enough to move the front master cylinder piston to make contact with the rear brake piston engaging the rear brakes. If the rear brakes are not adjusted correctly or a combination of worn linings and poor adjustment, the pedal may hit the floor/carpet before making adequate movement to engage the rear master cylinder piston with enough pressure to initiate adequate braking. The brake warning light was designed for those less than "attentive" drivers who may continue driving with only one system working, particularly if the rear brake are inoperative due hydraulic failure. The isolation valve closes off the master cylinder from the failing system minimizing fluid loss.

57 Black Tbird 312/auto

There appears to be a lot of misinformation and misunderstanding of how a dual master cylinder works. There are two separate braking systems, they never share fluid. The isolation valve is just that, to stop leakage from the system that has the leak. It does nothing for the fluid in the system that is working. I find it odd that the link Mark provided doesn't mention anything about the internal safety devices in the M/C.

Here's is an interactive explanation on how the dual M/C works to prevent total loss of your brakes. As said before if your brakes are not set up correctly to begin with or your travel is insufficient then the safety factor is not going to work.

http://auto.howstuffworks.com/auto-parts/brakes/brake-types/master-brake.htm

My own brake system on my '55 is out of a '72 Granada, M/C, power booster, disk brakes and rear brakes. I don't even have the "isolation valve/warning light installed, nor is it needed. It is just an another safety item in ADDITION TO the dual M/C.

Am I a brake specialist. No, but I have done quite a bit of research on brakes.



"The Master Cylinder"

Enjoying life at the beach in SOCAL

Steve- no, this thing's an expensive paperweight until either I can 1) get the brakes sorted or 2) the return of nice weather (whichever comes last) I also smell subterfuge inasmuch as vendors "whitebox" parts. Nothing new there though, I suppose. Seems if anyone had ever successfully accomplished what I had hoped to do, I'd have found a trace of it on the interweb, by now. After reading about M/C's & distribution valves/ switches not working as intended, I'll be more conservative in my thinking for safety's sake. Thanks for the head's up. /Duck

BOO- YA!!!

I think this is the tread Steve is referring to... http://forums.y-blocksforever.com/Topic84997.aspx#bm86383

This doesn't answer the dual circuit/single booster question for drums. Boosted front-only seems to work well for disk-drum setups, but I don't think I would want to boost only the front of an all drum setup.