Upgrading my Master Cylinder & Prop Valve - Thoughts On This Combo?

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MobileCustoms

MobileCustoms

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Here's what I have and my plans:
67 Notch, currently with 4 wheel drums. Future plans to upgrade to front discs but not right now.
My master cylinder is weak and I want to replace it right away.

I am thinking of buying a master cylinder for a '73 Dart/Duster setup for front discs, rear drums & manual brakes. I can get one from Rock Auto for about $45 plus shipping.

I am also thinking I will need an adjustable proportioning valve in the rear brake line, planning to buy that from Dr. Diff, most likely.

Will this setup work OK with my current 4 wheel drum setup as well as once I upgrade the fronts to disc brakes? Will I need a different pushrod?
Am I on the right track or totally whacked??? LOL

Want to place the order today in hopes of getting it installed before the Street Machine Nationals this weekend.

Thanks!

-Doug
 
It will work w/ drums, just set the prop valve for max rear brakes (screw in, I think). The rears only do ~30% of the braking. Must be less in my Plymouth Voyager since the rear shoes are still good at 205K miles.

I put a booster/MC on my 65 Dart and prop valve, for eventual disk brakes. I later read many here say they are OK w/ a manual MC and front disks, but get the smallest bore you can find (15/16" or 7/8"D). If you do want a booster, there is a new $130 one w/ MC on ebay. Not avail when I did mine, so my cheap approach was stand-off brackets from a 74 Dart and booster/MC from a cloud car (see avatar).
 
Drums do not have a prop valve. The difference in the master is that drum masters have what is called a "residual pressure valve" which the disk section of the disk master does not have. On my 67, I didn't even change the original 67 9" drum master. I simply ran a nail through the residual valve(s) (I have 4 wheel disks) and used the old master
 
BillGrissom;1970907837 said:
When I look up the master cylinders, it looks like the ones for the manual setups all have the larger bore and the ones for the power brakes have the smaller bores.
Do I want to use one designed for power brakes even though I am keeping it manual???

Thanks again
Click to expand...
 
MobileCustoms said:
When I look up the master cylinders, it looks like the ones for the manual setups all have the larger bore and the ones for the power brakes have the smaller bores.
Do I want to use one designed for power brakes even though I am keeping it manual???

Thanks again
Click to expand...
Many here use a 2-bolt MC for a 90's Dodge truck, on a 2-4 bolt adapter plate ($30 ebay).

The smaller bore will give an easier pedal, at the expense of slightly more travel. Many think the smaller bore in a "power MC" is backwards, but they aren't considering the lever ratio in the A-body stand-off brackets.

Another concern is that the manual brake rod has a rubber bushing on the end which locks it in the MC piston. The MC piston might have an internal groove to help, but should still lock fine in a "power MC". At least, I was test-fitting and couldn't remove the brake rod (64 Valiant) from the 99 Breeze "power MC" I used, and ended up ripping the rubber bushing in doing so. A manual MC also has a rubber dust bellows that bolts to the MC. On the power MC I used, I super-glued a bellows to the protrusion (post w/ photos).
 
Thanks Bill, I appreciate the input!
So couldn't I just use this 4 bolt power MC from a '73 Dart/Duster and skip the 4-2 adapter plate???
It also has the smaller bore size.
 

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This is from my build thread. It was recommended, so I did it and works great.

340sFastback said:
Very cool car with the V8, console/buckets, and 8 3/4" rear. Definitely a unique combo for sure. You got real lucky with those floors and trunk too. I recommend a 15/16" master cylinder for reduced leg effort. Order one for a '73 340 Duster with power disc brakes. It will bolt right in to a manual brake car. 7/8" rear wheel cylinders help to balance the brake system too along with a proportioning valve.
Click to expand...
 
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