Dual master cylinder - for stock drum brakes

[Thomba48]

Hi,

I am still running drum brakes (with the usual underfloor master cylinder set-up). And they actually do work fine. So why changing it? But just having a single brake line is something I want to address.

 

I have surveyed this site and online and yet have not come across a dual master cylinder that would work for my purpose. ECI I have spoken with, but their system only works with a disc brake set-up.

 

What I am looking for is a kit, not a work-around solution ideally, as I am not the biggest technical genius :-)?

 

Any solutions are kindly appreciated.

 

 

Thom

Edited February 6, 2020 by Thomba48

[Frank Elder]

A lot of popular 60s cars and trucks ran all drums and a few had power brakes to boot.....I believe @Dodgeb4ya runs assisted brakes which should be dual pot under the floor.

[Sniper]

As far as I know there is no kit.  You will have to piece something together.  ECI makes a bracket to mount a dual master cylinder where your master now resides.  It uses a 67-72 Mustang master cylinder.  If you can find a Ford M/C that is in an all drum system that uses similarly sized wheel cylinders then it should do the trick. 

 

ECI http://www.ecihotrodbrakes.com/chrysler_master_assemblies.html

 

I looked at the Mustang wheel cylinders and they seem to be of similar size as yours, assuming we are talking about the P15 here. The Mustang has one double sided front wheel cylinder, per side, with a 1.125" bore, the P15 has two single sided front wheel cylinders with the same sized bore.  The Mustang has one double sided rear wheel cylinder, per side, with a 0.875" bore, the P15 has one double sided rear wheel cylinder, per side, with a 1.125" bore and this difference may be the issue. 

 

So I decided to look at what other Ford products use the same master as the Mustang, seems most, if not all the Fords used it.  I decided to look at the full sized Ford's wheel cylinders and the full sized ones might be the donor you need.  A 70 Galaxy with all drums has a 1" bore drum master cylinder that should fit that bracket and uses a 0.906" rear wheel cylinder and the same sized front wheel cylinder. 

 

I hope this helps.

 

 

[Bobb Horn]

On my 48 Dodge, I used a Mustang II MC, with a simple piece of angle steel to attach it too.    I used a longer push rod going through the original MC.   Worked great..

[Frank Elder]

https://butchscoolstuff.com/42-53-plymouth-41-53-dodge-frame-mounted-brake-pedal-kit-2475bc/

[61spit]

That looks like it would be great but the description of it says it is for automatic transmissions only and requires offset trans cross member for Booster clearance. Can it be adapted to standard transmission applications? Has anyone done it?

[Thomba48]

10 hours ago, 61spit said:

That looks like it would be great but the description of it says it is for automatic transmissions only and requires offset trans cross member for Booster clearance. Can it be adapted to standard transmission applications? Has anyone done it?

That would interest me as well. 

[Thomba48]

I have contacted butchcoolstuffs and I can second that his kit only works with an automatic transmission. The only solution he mentioned was the one already being indicated by Bobb. For that their master cylinder could be bought. But when it comes down to it theirs is just a standard MC1321H, which you can purchase almost anywhere.

 

A shame

[James_Douglas]

I understand the impulse to convert to a dual master cylinder. Redundancy is your friend in safety systems.

 

That said, I have been running a single master cylinder for over 20 years in San Francisco and greater Bay Area traffic and it only failed once. That failure was right after I purchased it. I had a bad rear wheel cylinder. I purchased a new one from NAPA and put it in. About a month after that it blew.

 

When I took it apart I could see that the seal had a manufacturing defect. After that I always inspect all seals in all brake items even if new.

 

In the big Desoto I have a remote fill container up on the firewall. The end plug on the cylinders will screw into the top and you can just run a line up to the firewall. I use a white racer one so that I can just look and see how the brake level is doing.  I use modern steel braided flex lines in place of the rubber. I new NAPA line got a bulge in it after about 14 months. So much for quality.

 

My single master cylinder was sleeved with brass, but the man who did it has retired. You can get them done with stainless as well.

 

If you rebuild everything carefully and keep an eye on it, the single unit system works fine. I think the real reason they went to a dual system was the lack of proper maintenance on thousands of peoples part that of course then lead to bad accidents.

 

James

[Loren]

James has a point.

If you’ve ever experienced braking with a dual circuit system that has one side in failure mode it doesn’t give you much confidence.

First of all a dual circuit Master Cylinder has both circuits in one cylinder bore. Meaning when the driver pushes on the pedal the first circuit pushes not only on it’s brake cylinders but also on the secondary cylinders. One being in line with other. A failure is evidenced by pedal movement thru the failed circuit then finally the good side. Lots of pedal travel with nothing happening.

When you have a Master Cylinder that complicated lots of things can go wrong. There’s an old saying “Keep it simple”.

The reason the Butch’s kit only works for automatics is that there is no provision for a clutch pedal which limits it’s use to engine/transmission swaps.

The dual brake systems I’ve seen usually divide the system front and rear which is easiest to do. However, 80% of your braking power is on the front. A better system is the SAAB system (1964) of “Dual Diagonal” brakes where one front and the opposite rear are teamed on each circuit. Volvo went them one better by using both rear wheels and one front for each circuit but that’s way too complicated.

 

If one were intent on improving the Plymouth brake system, it’s my humble opinion going to Desoto 11 inch brakes and finding a way to put a remote reservoir for the Master Cylinder under the hood would be the biggest improvement. You could get all Guru and put a level warning light on the dash for the brake fluid. Even if the system was beginning to fail you’d have plenty of warning with fluid loss being the indicator. Simple with little re-engineering involved.

[Sniper]

Anyone that has ever blown a brake hose or wheel cylinder seal in a single circuit setup will never care that it takes more brake pedal travel in the dual setup to get brakes.  At least you will have some brakes with the dual circuit M/C and you will have zero brakes with the single circuit M/C, regardless of how big your reservoir is.  Hydraulic systems do not build pressure unless they are sealed.

 

I've had a single fail on me twice since 1983 and unless someone is bent on a 100% original car that's only driven on and off a trailer then it's wise to go dual circuit.

 

Any other reasoning is just self delusion, imo. 

[Sam Buchanan]

What I would really like is a dual cylinder setup like I had on the StalkerV6 kit car:

 

 

 

 

 

That provides redundancy, ease of balance and a decent pedal even if one cylinder goes down. These were Wilwood components but coming up with a way to convert our brake pedal to something like this would be a challenge....hmmmmmm........a master pushrod going through a gutted master cylinder connected to a balance bar then two cylinder pushrods......

Edited February 9, 2020 by Sam Buchanan

[Loren]

1 hour ago, Sniper said:

Anyone that has ever blown a brake hose or wheel cylinder seal in a single circuit setup will never care that it takes more brake pedal travel in the dual setup to get brakes.  At least you will have some brakes with the dual circuit M/C and you will have zero brakes with the single circuit M/C, regardless of how big your reservoir is.  Hydraulic systems do not build pressure unless they are sealed.

 

I've had a single fail on me twice since 1983 and unless someone is bent on a 100% original car that's only driven on and off a trailer then it's wise to go dual circuit.

 

Any other reasoning is just self delusion, imo. 

 

Plymouth and Chrysler cars in general were the first mass market cars with hydraulic brakes. From the first Plymouth in 1929 until dual circuit brakes became mandatory in 1967 single circuit brakes did just fine. The argument against single circuit brakes is exactly the same as the one against hydraulic brakes in general made by Henry Ford. However, if you've ever driven a mechanical brake car that is out of adjustment you will willingly (and happily) drive a single circuit hydraulic braked car.

I have never had a brake line fail by bursting. I have had to replace brake lines which de-laminated internally and caused fluid blockage. As it happened that was on a dual circuit system and it still wouldn't stop.

I have raced a car with a dual circuit Master Cylinder, where the Master got fried by a broken exhaust pipe. It made for "interesting" braking performance to be sure...but I finished the race.

The rarity of broken brake lines is more than made up for by the Plymouth parking brake system. That brake band will stop a car!

So...you pays your money and you takes your choice. Simplicity vs complexity a good discussion.

What causes a loss of brakes in a single circuit system is loss of fluid. If one checks the fluid once in a while and notices a fluid loss...problem solved. With a Master Cylinder under the floor board you're not as likely to do that. With my suggestion of a remote reservoir under the hood you'd be more likely to check it and you'd have a lot more fluid to lose. Taken one step further to add a level warning light satisfies safety and simplicity. In my mad mind such a system would actually be safer than a dual circuit master cylinder under the floor boards. But then it's my opinion.

[Sniper]

Don't believe I said anything about brake lines failing.

 

I had a hose fail, and I had a wheel cylinder blow it's guts out and yeah the PARKING brake eventually stopped it.  But if there was anyone in front of me when this happened that's who would have stopped me.

 

The "complexity" of a dual circuit master cylinder is fairly minimal from an installation point of view especially if you are still running an all drum setup. 

 

I will reiterate, hydraulics only work if the system is sealed.  You breach that and it matters not how much capacity your reservoir has, you will have no pressure with a single circuit master cylinder.  You will just have more fluid to pump out the hole while you try to panic stop.  With a dual circuit system you will retain some braking and even that reduced amount will work substantially better that trying to stop with the PARKING brake. 

 

 

[Bobb Horn]

On ‎2‎/‎9‎/‎2020 at 12:27 PM, Sniper said:

Anyone that has ever blown a brake hose or wheel cylinder seal in a single circuit setup will never care that it takes more brake pedal travel in the dual setup to get brakes.  At least you will have some brakes with the dual circuit M/C and you will have zero brakes with the single circuit M/C, regardless of how big your reservoir is.  Hydraulic systems do not build pressure unless they are sealed.

 

A few years ago, in my 38, not far from home, the front brakes went out, but I still had rear brakes.    I have a Ford dual MC setup, with my stock brake drum setup.

 

[Matt Wilson]

A friend of mine has relayed his experience with a failed single-circuit brake system in a 60's Mustang.  He was driving along, and stepped on the brake pedal, and there was no response.  He tried the brakes numerous times, to no avail.  He said that was the most horrifying experience he'd ever had.  He was able, by luck alone,to escape injuring anyone or damaging his car.  It turns out that a steel brake lineline had rusted through, with no sign of trouble until he had complete loss of his brakes.  He lived on the coast in Texas, and the lines had rusted out after 30-odd years.  That's why he has been absolutely insistent that I install a dual master  cylinder on my '49 Power Wagon, which I am in the process of doing now.  I've heard of one Power Wagon owner who was able to stop his truck by using the parking brake when his brakes failed, but frankly, I don't know how he managed it.  It's quite a reach to grab that handle sticking up through the floor at the center hump, and I'm sure I'd lose sight of the road in front of me if I had to lean over that far.  I wouldn't want to rely on that.

[Loren]

I’ve said my piece on this topic before so I’ll try not to be redundant.

If you are determined to use a dual master cylinder, all you need to do is find one with the same size bore.

If I were to do such a thing, I would not split the system front to rear. I’d split it diagonally one front wheel and one opposite rear wheel on the same circuit.

A dual master cylinder just means you have two single circuits. Splitting it diagonally means more hard lines, connections and another rubber hose. More points of potential failure.

Before a driver goes into panic mode with a brake problem, they ought to do some training.

Go out and figure out what you have to do when you can’t use the brake pedal.

As I said before I finished a race in a car with a seriously malfunctioning brake system.

So how do you do that? Very carefully and with zero panic. You’re the driver, drive!

I had an MG TD that had an intermittent issue where the pedal would go right to the floor and then a minute later all was well.

Annoying but it did build character! I never wrecked it.

My race car partner called me a few days after the race and told me he wanted to move the car and forgot I told him it had no brakes.

The shop was on a pretty good hill and the only thing that stopped it (and him) from going down and hitting his house was a stack of tires.

I think he was offended when I laughed at him.

[Sam Buchanan]

I have conflicted feelings about the necessity of a dual-circuit cylinder. I had a brake failure in my 1964 Beetle as a young heathen when a line turned loose and we rolled past a stop sign out into an intersection, the only thing that saved me was the lady coming from my right being alert and nearly getting stopped before caving in the passenger door. That experience has remained stuck in the recesses of my brain....

 

On the other hand, my dad bought a new '56 Savoy which I learned to drive nearly ten years later and was still running when we sold it after his passing in the late '70's. The odometer showed 144K+ miles even though it had quit spinning a few years previously. That Plymouth never gave us a moment's trouble with the brakes....we never even considered that it had a single-circuit cylinder.

 

So...after being determined to install a dual-circuit cylinder in the '48 P15 when I bought it a year ago, (and an abandoned attempt to convert to a dual-circuit cylinder) I'm attaining a level of peace with the single-chamber cylinder. I've replaced the entire brake system so have confidence in the integrity of the lines and cylinders. I also have a parking brake that works pretty well after careful adjustment. I also try to drive with a similar mindset I used on motorcycles years ago.....be conservative and try to leave an 'out'. Driving any machine is a risk........even though the dual-chamber vision hasn't disappeared completely....I'm coming around to depending on components what worked quite well so many decades ago. 

Edited February 14, 2020 by Sam Buchanan

[James_Douglas]

On 2/13/2020 at 4:45 PM, Sam Buchanan said:

I have conflicted feelings about the necessity of a dual-circuit cylinder. I had a brake failure in my 1964 Beetle as a young heathen when a line turned loose and we rolled past a stop sign out into an intersection, the only thing that saved me was the lady coming from my right being alert and nearly getting stopped before caving in the passenger door. That experience has remained stuck in the recesses of my brain....

 

On the other hand, my dad bought a new '56 Savoy which I learned to drive nearly ten years later and was still running when we sold it after his passing in the late '70's. The odometer showed 144K+ miles even though it had quit spinning a few years previously. That Plymouth never gave us a moment's trouble with the brakes....we never even considered that it had a single-circuit cylinder.

 

So...after being determined to install a dual-circuit cylinder in the '48 P15 when I bought it a year ago, (and an abandoned attempt to convert to a dual-circuit cylinder) I'm attaining a level of peace with the single-chamber cylinder. I've replaced the entire brake system so have confidence in the integrity of the lines and cylinders. I also have a parking brake that works pretty well after careful adjustment. I also try to drive with a similar mindset I used on motorcycles years ago.....be conservative and try to leave an 'out'. Driving any machine is a risk........even though the dual-chamber vision hasn't disappeared completely....I'm coming around to depending on components what worked quite well so many decades ago. 

I have never had a master cylinder fail. I have had a wheel cylinder fail, like I said, it was new one from NAPA. I had a fairly new hose failing...I replaced them all with Russell Racing Steel Braided. In most instances with a single master system, there is a telltale sign that something is wrong. I am comfortable with a single cylinder, but I check the fluid level every week and inspect the underside of the car every quarter. Once every 5 years I replace all the fluid in the system. Once every decade or so I replace all the seals and check the guts. I drive the 1947 in the hills of San Francisco and only that bad new wheel cylinder is let me down.

 

All of the cars my family had as kids had single master cylinders and they never had an issues at 100K or more miles on them. I really do think that the reason the feds went to ordering dual cylinders was that as cars got older and went to second or third owners that may not have properly maintained them and they started to see failures. A properly maintained single system is not unreasonable from a safety perspective.

 

My 1949 has 4 wheel disc brakes, the only major non-stock thing on this car,  with a single cylinder and a Midland-Ross remote power brake booster. Car stops TOO good. The rear calipers have the Cad-Eldo rears with the cable operated parking brake. It will slow the car just as good as a failed dual cylinder operating on two wheels.

 

James.

Edited February 16, 2020 by James_Douglas

[Sam Buchanan]

This is a different car family but I had a dual-chamber master cylinder in the '74 Beetle fail last year. Fortunately I found it as I was preparing for a drive so danger was avoided. But the cylinder was mush with no braking action (discs on front, drums rear) and it had given no prior warning when the car was driven a few weeks previously.

 

Guess this emphasizes the importance of a pre-flight inspection.