Mopar Action On-line – Tech Questions
Tom Foley, East Palestine, OH, 1964, Plymouth, Barracuda, 273
I have a 1964 Barracuda with non-power drum brakes. I wouldlike to change from the single reservoir master cylinder to a dual reservoirmaster cylinder.
What parts do I need to do this ?
Thank you, Tom
This is a very good question that has not been addressed much in print.
First, you need a dual master cylinder. Basically, any stock ’67-up one will work. You can also use one from a disc brake car, such as the cool MP aluminum one that was sold in the 1990s. (MP’s current truck-based “slanted reservoir” one is not so great). But if you do this, you must be sure that all your wheel cylinders have “expanders” in them (the little dished steel gizmos that “back up” the piston cups.) Virtually all wheel cylinders, and rebuild kits, sold in the last 25+ years have ’em.
If you use a later aluminum 2-bolt cylinder, you’ll also need the MP, or similar, 2-to-4-bolt adapter.
Then you need to plumb the dual-circuit setup. The easiest way to to this is to use a junction-block setup from any ’67-up drum-brake Mopar. This provides a convenient point to run all the lines to, and keeps the front and rear circuits separated. You can either make up your own lines, or, easier by far, buy one of the readily available pre-bent tubing kits designed for 1967 cars. Even though the A-body got wider in ’67, the kits will fit pre-’67 with very little difficulty.
The hardest thing to find will be the junction block (tee). To the best of my knowledge, the aftermarket never supplied this part, the factory has long-since discontinued them, and there are currently no known repros. So this will take some junkyard scrounging. But you can use one from ANY ’67-up drum brake Mopar, right up through the drum-equipped 1976 A-bodies – the last all-drum Mopars! Do NOT use one from a disc-equipped car.
The plumbing connections should be fairly obvious, if not, consult a FSM from the same year as the block. There is one electrical connection on the block, just ignore it. It was there to satisfy a Federal regulation that went into effect in ’67, but was really meaningless. You could also just disconnect the rear line from the existing tee, block that port with a proper plug, and run the vertical line to the front of the new master (changing to the appropriate fitting at the m/cyl end). Then extend the rear line (all fittings must be double flared) to the rear outlet on the m/cyl. That would be the super-cheapo way to go, and it would work 100% A-OK.
Bleed the master cylinder itself first, then all lines starting with the longest one (i.e., right rear) and you’re done.
Personally, I would not drive any Mopar without this modification, including 100-point restorations and/or survivors. (It won’t be 100-point after the brakes fail and you rear end your trailer, make a speed-bump out of the judge, etc.)
PS / NOTE:
We published a super detailed article on a simplified way to do this swap in our April, 2005 issue.