Thoughts on single reservoir, single piston master cylinders.

Well what are your thoughts, pros and cons, good or bad experiences, ect. Im all ears and eyes on this one.

Lets have a talk,

Thanks

Hack

 

I've had both with no problems. However, I did lose a caliper with a single reservoir and lost all brakes.

 

I've driven my '56 Nomad 300,000 miles in the last 22 years with a single reservoir. However, I have also had a wheel cylinder blow and lost my brakes at a stop sign exactly one block after I had stopped for a train at a railroad crossing. I shudder to think what might have happened had it blown one block sooner.

I've become more diligent about regular inspections of my brakes since that time.

 

What "cons" with a dual master, and what "pros" with a single Single system masters have not been used on production US cars/lt. trucks since 1966, and for good reason. If you choose to use one, that's your prerogative, 'cause some suppliers still sell the dam things, but not knowing or understanding the safety advantage of dual masters in this day and age is sad,.... although you're not alone!

 

In my opinion, they are always to be considered on the brink of failure, and to be removed as soon as is possible.

If a car comes into the shop with one, it leaves with a dual. If the customer is not receptive, I do not work on the car.

Life is too short to take this kind of risk, especially when an inexpensive solution is easily obtained. One failure is all it will take to convince you, if you survive.

 

You are always one leak away from disaster.
Do you have all new lines and cylinders? If not you are probably running something that is ready to cause death or disaster at any time.
Remember, going is optional. Stopping is mandatory.

 

Stock single on my 49 Hudson and good brakes BUT the Hudson has a redundant safety in case of a hydraulic failure. Once the brake pedal gets halfway to the floor mechanical linkage starts engaging the parking brakes.

 

Replaced all the brake lines, rubber lines and wheel cylinders on my '54 Buick.
A couple months later, blew a rear wheel cylinder and lost all brakes.
Stomped on the emergency brake, but guess what? The emergency brake only works on the rears... and with a blown rear wheel cylinder, the right rear drum and brake shoe was coated with nice, slick DOT 3.
A car won't stop with one out of four brake drums.

Go dual. There is NO advantage to single, and people talking about regular inspections and maintenance on brakes making a difference are talking out their ass, unless their "regular inspection and maintenance" also includes taking apart the wheel cylinders and somehow making sure the seals are never going to fail.

Especially with the quality of today's parts; I've also had two new wheel cylinders on my '61 Suburban fail. Dual reservoir conversion, so it wasn't anything more than annoying.

-Brad

 

Lost a wheel cylinder about 5 years ago on my 56 Chevy going downhill...finally stopped with the "emergency" brake after coasting through a busy intersection...Replaced single pot with a dual, never looked back. Easy fix, peace of mind.

 

I guess I really need to rethink my "originality" position here. For all those I share the road with especially. I will start chasing down what is needed to convert.

 

I have a single, and a working e-brake, yet I am going to convert to dual very soon.

If what you have is a '66 Mercury Comet, then all you need (besides lines and time) is the dual cylinder from a '67 Comet. Keep the same bore size, and Bob's your uncle.

Cosmo

 

About 6 years ago a friend of mine stopped by with his '34 coupe. After chewin' the fat for a while we decided to run down to the corner for a beer. Pulled out of the drive and didn't even get into overdrive when a woman ran a stop sign aand plowed into us ripping the front wheel and end of the axle off the car. We were runnin about 50 and were spun around and heading for a tree. He slammed on the brakes only to find that there were none. We missed the tree but snagged a culvert bending the other end of the axle.He couldn't figure why the car didn't stop, he had a dual chamber master cylinder, but the rear didn't make a bit of difference. Before this happened the car would stop an a dime. So how many cars out there have the dual cyl and know if they're working. How many people disconnect one end or the other to check 'em? Very few I think. 90% or more have the dual and have never had a problem, so they don't worry about it. So who knows? I have 3 cars with dual cylinders and 2 without. Never had any problems with either. I have no preference. Maybe if I had one fail I would think different. As far as my buddys '34, he bought a new axle, buttoned it up and is back on the road. He did however change the cylinder to a new one of the same brand. Brakes work fine............ for now. Norm

 

I think dual cylinders only work if you use either the stock check valve or an add on one. It is the ball in the check valve that seals off the front or rear lines in a pressure failure.

 

If you have a dual circuit master cylinder, and one circuit is already not working, it should be readily apparent.

 

Do you know of one application, or can you post a picture of the "check valve", that seals off a failed circuit? If you're referring to the differential pressure switch that many think does this, well, it doesn't.

 

Here we go again.

 

No, there are two seperate lines from the master cylinder. In most failures you will still have either front or rear brakes. On my stuff I'm running dual systems, no reason not to have the extra safety.

 

I have participated in the bleeding of a brake system with a dual chamber master cylinder. When I opened the bleeder on the front wheel, the brake pedal went to the floor. Opening a bleeder is the same as breaking a line, or blowing a wheel cylinder. I have been told that the mistake we are making is not using the brass block that is in the brake system of production cars. I don't know.. I do remember that Detroit installed the dual chamber master cylinders when they introduced disk brakes. There wasn't enough fluid capacity in a single chamber to actuate both disk, and internal expanding brakes, so they were forced to engineer a dual chamber. Soon all the manufactures touted saftey reasons in an attempt to offer something new to the public. Now 30 years later everybody belives dual chambers are safer. Bleed your brakes and see if your pedal go's to the floor..

 

exactly....

 

Yep. What's next...throwing red paint on cars and calling people baby killers?

No, I'm not saying dual masters are a waste of time either. Just seems like some think the sky is falling.

 

No, it's just a simple thing to upgrade the safety of a car.
I've driven plenty with single reservoirs. I like dual better.

 

I value my life and would never run anything on a car short of a dual system, If you have a failure with a single reservouir thats your brakes gone!!

 

"The amount of safety precautions I take on my personal car is just right. Anyone doing anything more is a pussy, and anyone doing anything less is a danger to the entire world."

 

True that!

 

I blow a line on a single well master one snowing morning going to work . NOT GOOD....
new brake lines are a must ....

 

I just happen to be very close to bleeding an all new dual pot brake system. I'll see what happens after I've bleed all 4 wheels and have good brakes by cracking open a rear bleeder first and then a front. Could be interesting.

 

It's been 47 years, but many still don't believe dual masters are safer.

 

While I prefer dual systems, either setup is only as good as its engineering and maintenance. A dual master cylinder with bad seals can pump the fluid out until you have no brakes, just like a single cylinder.

A buddy of mine plugged the rear MC port while sourcing brakelines for his daily driver. Clever and stupid all at once, especially since he had another car to use, and didn't need to drive around on 2-wheel brakes like it was 1920.

 

Single pot MC`s are nothing but a funeral going someplace to happen.
Good luck.Have fun.Be safe.
Leo

 

I would readily agree that a dual system is safer.The question that has run thru my head more than one time is how I would do this on the 28. I have the early 60's chevy truck pedals that use the siamesed master,one side for clutch,one side for brakes.Is there a way to change this with out changeing pedals and all?