Will a dual pot master cyl for discs work on original 1964 booster?

[Big Bad Dad]

My 1964 Fury still has the original 10 x 2-1/2 power drum brakes. After doing a brake job, it does not stop well with the new, non asbestos, brake shoes. (It stopped very well with the old brakes, but they were well worn, and the cylinders started leaking.) I am considering changing to front discs, and know I will need a dual pot disc master cyl, add the required dual lines, and a proportioning valve. However, I'm not clear on whether or not I will need a different power booster. My original is the Midland Ross booster and the master cyl is the 4 bolt style. Anybody tried this before and can advise me? Thank You

 

[MIKESPOLARA]

You do not have to change to a dual just because of disc brakes. Your original master will work just as well after you remove the internal residual pressure valve if it has one.
However if you absolutely want to change then your booster is fine just have to make certain the pin length of the booster matches the hole depth of the new master
I'm going to guess your booster has a long pin so master has to have a deep hole to match

 

[Sixpactogo]

My experience has been the drum brake booster does not provide enough boost for the disc upgrade.

 

[MIKESPOLARA]

My experience has been the drum brake booster does not provide enough boost for the disc upgrade.

Whats the difference? calipers take no more effort then drums, they just stop better. Most OEM applications that had 4 wheel drum and optional front disc used same booster for both applications.

 

[Sixpactogo]

You can believe that if you want to but that is why when MOPAR got into the front disc brake business, they started using the dual diaphragm boosters. They're engineers are no different than any others in the mindset that they don't spend extra money when its not needed. What's the difference? Calipers are twice the size of a drum cylinder. Maybe that's the reason. I don't really have an answer except I had to learn that lesson on two different cars that I upgraded to front discs. A 70 Challenger and my 68 Charger. Neither one would stop worth a **** with the single diaphragm booster. The only change was upgrading to the dual diaphragm. Lessons I learned from Dr Diff himself.

 

[Big Bad Dad]

Well, I have been doing research on the internet all afternoon about this. Discouraging. It seems that B bodys from 66 up are covered by about everyone. The early B bodys 62 to 65 are not. I can find boosters and master cylinder conversions for early cars that came with manual brakes. But for those of us with early cars that had factory power brakes, it seems we are out of luck. Something is apparently different in the factory firewalls and mounting plates. Dr. Diff recommended having my booster rebuilt, but I don't have a problem with my booster. It works. I am tempted to just bolt a later disc/drum master cylinder to it and hope for the best. But then, Wayne at TheRamMan said in a video that the Midland wouldn't power a disc brake master cylinder. And I see conflicting opinions on that here on FBBO. sigh........

 

[MIKESPOLARA]

Well, I have been doing research on the internet all afternoon about this. Discouraging. It seems that B bodys from 66 up are covered by about everyone. The early B bodys 62 to 65 are not. I can find boosters and master cylinder conversions for early cars that came with manual brakes. But for those of us with early cars that had factory power brakes, it seems we are out of luck. Something is apparently different in the factory firewalls and mounting plates. Dr. Diff recommended having my booster rebuilt, but I don't have a problem with my booster. It works. I am tempted to just bolt a later disc/drum master cylinder to it and hope for the best. But then, Wayne at TheRamMan said in a video that the Midland wouldn't power a disc brake master cylinder. And I see conflicting opinions on that here on FBBO. sigh........

That's funny, "wouldn't power a disc brake master".
Larger boosters are better, but the biggest problem with boosters is low engine vacuum. A dual 9" booster is very good for stopping power. What is the size of the 64 booster?
The only thing that changes in a master is it's bore size, hydraulically speaking. Bore size of the calipers determines if a 1" bore master or 1 1/8" master is better suited for the disc brakes. Most Mopar factory calipers work well with a 1" bore master. The 64 has a 1" bore master.

 

[matthon]

My 64 had the same power drums, I was lucky as a friend had bought out a parts store way back and had 4 sets of shoes.

Up until then, even with a rebuilt booster, new '65 drums all around, and a dual circuit master, the new shoes would shine up the drums and it wouldn't stop.
Pull the drums, sand them down, it would stop for a day or two.

Later shoes don't fit, a few of the holes have different shapes/locations.

My 62 had manual drum, I ordered everything from Dr D to convert to front disc, just Mopar single piston stuff, modern/plastic master, splurged for the complete rear drum setup as well.

Imo, the kits to convert manual to power have garbage parts, specifically the master.

To convert the 64 to manual disc, need the manual mc firewall bracket, and move the rod to the other hole on the pedal.

I think you could also just order all 66 drum stuff, shoes, springs, etc.
Not sure if the backing plates are the same between 64 and 66 so might need those as well, if they bolt on to the tapered axle.
If that works, I hear the drum brakes from MuscleCar Brakes are great.

 

[Dragon Slayer]

66 and earlier used a single large master cylinder that operated all 4 brakes. In 66 with a disc option there was also an add on that made the reservoir larger.

In 67 federal mandate for a dual MC to provide extra safety by having rear and front brakes independent via 2 pistons/reservoirs.

Mopar training documents discuss the larger fluid chamber to account for the large piston of the front disc brakes. While a smaller may work initially, as the pads wear and piston extends out further you might wind up with low level and potential the smaller piston diameter of MC and corresponding volume of fluid is insufficient to generate the necessary pressure.

 

[440 PHIXX]

I can’t imagine not upgrading to a dual. I’ve lost one side at least twice. I didn’t wreck either car.

 

[Big Bad Dad]

OP here. The answer is that I installed a modern master cylinder with a 4 bolt to 2 bolt adapter to the original booster when I put the disc brakes on front of my 64 Fury. I got the brakes and the master cyl from Dr. Diff. It is working.