DUAL MASTER CYLINDERS ....... THE BIG MYTH?

Sorry. I just dug it up because it had good info on guys loosing brakes.

 

Q
Hahahahahahaha, I didn't even notice! I just keep seeing replies!

 

My dual MC [wilwood] piston moves about .343 to brakes full on. I don't think I can bottom the cylinder which I think would require maybe another .750(?) of movement. Could the MC be made so there is not so much extra travel? i.e. piston 1 closer to piston 2 and piston 2 closer to bottom of bore as long as the required stroke is known as in my case .343. Probably .080(?) travel just to close the ports

 

Well........I have the dual bowl MC on my "M-word" because everybody sez........"it's safer if you have a failure you STILL have 'some' brakes to get you stopped unlike that jelly jar that's on there.!
Cruis'in down the boulevard and the rear brake line finally rusts through AND........pedal went to the damn FLOOR!
I didn't have squat fer brakes. Dual/Beuall NADA...Nut'in!!
Thank the Lord it was NOT tourist season and a just about sun down because....with the help of a 5 speed trans and fancy clutch work, I was able to time all the red lights back to my house without incident.
(bu'cept my drawers which I filled up pronto!)
Sure wish I had the E-brake hooked up!!!!
6sally6

 

I had the same thing happen a couple years ago in the ****py 30 year old "modern" car. Rear brake line burst and all brakes were lost. All I can figure is that one or more of the internal seals is worn out, creating in effect, a single reservoir master cylinder.
I've had several other cars that lost the rear brake circuit and the fronts still worked fine.
I guess at worst a dual system is no worse than a single, and at best, it gives you okay brakes vs. none at all.

 

This thread is like the Crowds entertaining the Clowns at the Circus




A tandem M/C or Dual M/C's both need enough pedal travel to overcome the displacement that is lost when one circuit fails.

From a safety perspective they both achieve the same results.
Most of the time they will save your car and ruin your underpants.

 

Keep in mind the front brakes do the vast majority of the braking, therefore if you lose the front then it’s not going to feel like you have much for brakes.

 

And people give me **** for running mechanical brakes...

Alot of those junk GM style proportioning valves have a limiter inside them, when one side drops pressure it cuts flow down to the effected side. These valves are JUNK and hardly ever work right... Run you a good dual circuit master, adjustable proportion valve in line to the rear brakes and roll on.

Single master cylinder will work fine until mechanical failure happens, wheel cylinder, line blowout etc. At that time, best have an E brake handy... I did years on single circuit without E brake and looking back... Man was I dumb.

 

Yes, I've had them apart, and the parts are two pieces. But they're sandwiched inline with each other, so run in a common bore. Just spaced so each runs off one of the separate reservoirs.

 

To all the replys where a brake line blew out and they lost all stopping with a single master cyl. I say , if your driving with rusted or corroded steel lines you were playing with FIRE ! I agree a dual master is better than a single but can never make up for poor maintance . with either system all components ( lines , hoses , w. cyls , etc ) need to be checked often and kept freshened . I have never lost braking with a single master in 60 years .

 

The word for that is "yet". Let's hope that your luck continues.............
Anyone who has experienced a no brakes situation may have a different view regarding the importance of upgrading an antiquated system a little. Realisation through hindsight is a powerful motivator for those lucky enough to get another go.
No, it doesn't happen every day, but it does happen. Sometimes even with impeccable maintenance.

 

I had ****py brakes in my 59 El Camino for years. Thought it was ****py shoes. Always had to use the gears when stopping. Pulled it apart and found the master was leaking internally, and I had one functional wheel cylinder. I fixed it with another single pot and kits to the wheel cylinders, but the next step is to upgrade to a dual pot with all new brake lines. I figure 63 years is long enough for any remaining hard line. The master cylinder still looked perfect on the outside

 

When I was 16 in 1971 my first car was a 63 Catalina. It had a single bowl MC. It didn't blow completely but got really spongey on my way home one night, went to the parts house the next day with old one and the parts guy who was one of those car guys that every car crazy kid wanted to be. His cars were always awesome. Long sorry short I put the old MC on the counter and Jeff said, you don't want another one those piles of ****, He brought out a dual MC for a 67 Catalina and showed me what fittings and lines I needed to split the front and rear and how to fab a line bleeder kit to bleed the system by myself. He always said building cars was always about figuring out how to make them better faster and safer than what you started with. I learned a lot from guys like that back then and eventually became the car guy that they were, and I wanted to be back then. With the knowledge we have available today literally at our fingertips why would we even consider using technology that was barely okay 60 years ago. Especially when the safety of family, friends and strangers are at stake! Hell, even back in 1939 hot rodders realized juice brakes on a new Ford where a far cry from the stock ones on their 32! Be safe Larry

 

The key to not loosing all the fluid in one chamber is the floating balance valve that shuts off the side with the low pressure. Lots of 70's cars had them. If you bleed one side of the brakes, you had to bleed the other side to re center the valve, or one side would be shut off.

 

Many people keep saying this yet have never actually provided more info, I have not seen a factory application that does this, why would we require a tandem master if this was the case. I would welcome a specific application and the factory literature that confirms this is how they work.