Single Circuit Master Cylinder Question

[RexRod]

OK, I have a question for the pros. My brake parts vocabulary is not great, but I think you'll get what I'm after.

I was noticing Wilwood offers a bunch of single circuit master brake cylinders. Now most of the cars you see have two circuits or outputs on the same cylinder. One for the front brakes and one for the rears.

Is it possible and safe to power all four wheels on a street driven car with only one output circuit master cylinder? Or do you need dual outputs for four wheels. I am clear that a proportioning valve is needed to help tune the bias between the front and rear systems.

Thanks in advance for your brain power!

David

 

[LumenAl]

Many older cars came from the factory with single master cylinders, down side is one thing goes wrong, the whole system may fail as opposed to having front brakes on one and rear brakes on another. This is also why back in the day what we call parking brakes today where called emergency brakes as that is all you had once you had a failure in the braking system.

 

[der Spieler]

Cars ran single circuit master cylinders up until the late 60s when dual circuits became mandatory. I wouldn't mess with the single circuit myself. It's better to have all of the safety advantages you can have. My racer is going to only have brakes on the rear wheels but I'm going to have two calipers per wheel, the front calipers on one circuit and the back calipers on the other. If I can get the speed I want out of the car I want to be able to stop.

 

[Ted Brown]

Cars ran single circuit master cylinders up until the late 60s when dual circuits became mandatory. I wouldn't mess with the single circuit myself. It's better to have all of the safety advantages you can have. My racer is going to only have brakes on the rear wheels but I'm going to have two calipers per wheel, the front calipers on one circuit and the back calipers on the other. If I can get the speed I want out of the car I want to be able to stop.

If you want to be able to stop, you will be waaaay better off using drum brakes, I could tell you a good story about just this thing, but not now... The very best stopping power is drum brakes, period, bar none, trust me on this...

 

[RexRod]

Thanks for all the replies! It makes sense to me now why two circuits are better than one. It never occurred to me that if one system fails you still have another as a backup.

I'll definitely be using a dual circuit master on my future project. HA! My poor future project. At this point in time, I'm going to have to vicariously live my bucket dream through the rest of you!

Take care,

David

 

[der Spieler]

If you want to be able to stop, you will be waaaay better off using drum brakes, I could tell you a good story about just this thing, but not now... The very best stopping power is drum brakes, period, bar none, trust me on this...

If I'm trying to whoa it down from 200+ mph I'm gonna want my setup. Less brake fade and with two circuits operating 4 calipers I think i will get her done better. That and the chute.

 

[Ted Brown]

another thing about (single circuit master cylinders) You want to use two (2) one with a real small bore for the disk brakes 5/8" and a larger bore 7/8" for the drums.. this way you have great stopping power without using a power booster, or a real long brake pedal...

 

[Ted Brown]

If I'm trying to whoa it down from 200+ mph I'm gonna want my setup. Less brake fade and with two circuits operating 4 calipers I think i will get her done better. That and the chute.

Will not happen! you talk about FADE!! try it, you will learn the hard way... Just go to a nice big Chy drum brake, 12" x 21/2 or 3" CRS, with metalic pads, stop on a dime and Give you change, something your disk brake will not do... Check with Bob, owner of Power Brake Servive, in Long Beach, Ca. if you do not believe Me...

 

[RPM]

So Ted you are saying that all the fuel cars in NHRA and all the cars in NASCAR, all have the wrong brakes on them? I wonder who will tell them and straighten them out before they can't stop?

Looks to me those guys have an unlimited amout of $$$$$$$$ and could afford the best!!

 

[Ted Brown]

So Ted you are saying that all the fuel cars in NHRA and all the cars in NASCAR, all have the wrong brakes on them? I wonder who will tell them and straighten them out before they can't stop?

Looks to me those guys have an unlimited amout of $$$$$$$$ and could afford the best!!

All the money in the world will not always win... Just because they have money, does not mean they know more than people who work closely with different parts. Disk brakes are easy to work on and are usually lighter... I would have to say, that is why they use disk brakes, and they do not know better... Like I said, where is the money spent, (a ton is made selling brake pads, a real big amount) that is what people will tell you is best, it is all money to be made... If I were selling, I would tell you what you WANT to hear... wether it is right or wrong, why should I care? I have your money, but my car has drum brakes and out stops any with disk brakes. (on the rear)

 

[tfeverfred]

Okay, I have to chime in. I'm thinking a few hundred engineers at NASCAR or the factories would have a reason for going to disc. Heck, all you have to do is look at a drum setup, with all the springs and other primitive crap, to see that it's not a better way to go.

Drums are fine for a street car and were for many years, but disc are better. It's not a matter of money, it's called "advancements in technology".

Heck, a large rock dropped out the back of a car will slow it down too, but there's a better way.

 

[tfeverfred]

From Edmonds tech center:

"Though disc brakes rely on the same basic principles to slow a vehicle (friction and heat), their design is far superior to that of drum brakes. Instead of housing the major components within a metal drum, disc brakes use a slim rotor and small caliper to halt wheel movement. Within the caliper are two brake pads, one on each side of the rotor, that clamp together when the brake pedal is pressed. Once again, fluid is used to transfer the movement of the brake pedal into the movement of the brake pads.
But unlike drum brakes, which allow heat to build up inside the drum during heavy braking, the rotor used in disc brakes is fully exposed to outside air. This exposure works to constantly cool the rotor, greatly reducing its tendency to overheat or cause fading. Not surprisingly, it was under racing circumstances that the weaknesses of drum brakes and the strengths of disc brakes were first illustrated. Racers with disc brake systems could carry their speed "deeper" into a corner and apply greater braking force at the last possible second without overheating the components. Eventually, as with so many other automotive advances, this technology filtered down to the cars driven by everyday people on public roads."

 

[Rick]

From Edmonds tech center:

"Though disc brakes rely on the same basic principles to slow a vehicle (friction and heat), their design is far superior to that of drum brakes. Instead of housing the major components within a metal drum, disc brakes use a slim rotor and small caliper to halt wheel movement. Within the caliper are two brake pads, one on each side of the rotor, that clamp together when the brake pedal is pressed. Once again, fluid is used to transfer the movement of the brake pedal into the movement of the brake pads.
But unlike drum brakes, which allow heat to build up inside the drum during heavy braking, the rotor used in disc brakes is fully exposed to outside air. This exposure works to constantly cool the rotor, greatly reducing its tendency to overheat or cause fading. Not surprisingly, it was under racing circumstances that the weaknesses of drum brakes and the strengths of disc brakes were first illustrated. Racers with disc brake systems could carry their speed "deeper" into a corner and apply greater braking force at the last possible second without overheating the components. Eventually, as with so many other automotive advances, this technology filtered down to the cars driven by everyday people on public roads."

UH,OH are you sure Fred? Thats not what i hear.

 

[tfeverfred]

All those highly paid engineers can't be wrong. Or could they?

 

[der Spieler]

This is what is going on the back of my racer. I think it will give me plenty of whoa.

 

[RPM]

This is what is going on the back of my racer. I think it will give me plenty of whoa.

Looks like a good choice there Steve.