Gorilla Performance Bal-Bar Balance Bar Dual MC's NO BOOSTER Required
05-10-2010, 12:26 AM
#11
3rd Gear Member
Join Date: Apr 2008
Location:
Posts: 939
As to why the high end cars don't have them, there's a number of reasons I can think of. Cost being one of them.
Do you currently own and drive a car with dual MC? If not.........
05-10-2010, 02:16 PM
#12
6th Gear Member
Join Date: Apr 2007
Location: California
Posts: 10,468
http://www.wilwood.com/MasterCylinde...ter%20Cylinder
That's the Wilwood unit I've been running for years and years and years with 0 issue and no booster.
http://www.wilwood.com/MasterCylinde...ter%20Cylinder
Those are their combo single units, about $72 each. So for 2 m/c you're looking at about $145.
http://www.wilwood.com/Pedals/PedalList.aspx
Those are pedal assemblies, $120 for a dual m/c mounting setup. So then you're looking at a total cost of around $260 for the master cylinders AND pedal assembly to run a dual setup. And that's for high end, high quality aftermarket stuff. In fact those Wilwood parts I just listed are what you'll find on nearly every single Nextel Cup Car in the country(and many other race cars as well). And the remote adjuster is only another $52.
That's a lot cheaper than a good tandem m/c and a good booster. The stuff I listed is top of the line for quality, you'd have to get the cheapest most unreliable booster and m/c to beat that price. And also consider that boosters are "a dime a dozen" due to the economies of scale. They were put on millions of production cars, so costs from mass production is on their side, and they're still on average more expensive. And then you still need to add in the cost of a pressure reduction device as well, which a balance bar assembly doesn't need.
If dual m/c were as/more effective, companies would have done it a LONG time ago, because they're MUCH cheaper, especially if mass produced. But they didn't, because the braking requirements to low speed and light braking require different bias than high speed and heavy braking.
A lot of newer performance and luxury cars are actually going to electronically controlled brake biasing. They use different systems, some have an arm attached to the rear axle/suspension so as the suspension moves up and down from loading and unloading, it calculates effective tire loading and alters rear system pressure to compensate. Others actually use ABS sensors to determine how much slip exists in the tires from front to rear and adjusts bias base on actual wheel slip. But in all cases they're altering rear line pressure continuously across the whole range of conditions, not providing a static built in pressure ratio like a balance bar assembly does.
But the point is that a street car needs different biasing requirements than what a balance bar setup can deliver. Under maximum braking a balance bar setup is the superior setup, which is why it's on nearly every race car out there(where it's allowed). But street cars operate not only under maximum braking, but minimal braking and everything in between. A balance bar setup can provide the most effective biasing under 1 braking condition, but it's less than optimal under all other conditions. A hydraulic reduction type device(used on every production car on the planet) can provide very effective biasing across the entire range of conditions, but can't provide optimal biasing under any 1 condition. It's different systems for different requirements.
A dual m/c setup with a balance bar on the street has the potential to be extremely dangerous. While you may have a setup that is less than optimal under some conditions but has no major issues, balance bar setups on the street have the potential to create a brake system that's highly imbalanced in certain conditions. If you end up in a situation where you're doing nearly all of your stopping with the front wheels, even a very minor variation in traction at the 2 front wheels can result in the car pulling violently to one side.
That's the Wilwood unit I've been running for years and years and years with 0 issue and no booster.
http://www.wilwood.com/MasterCylinde...ter%20Cylinder
Those are their combo single units, about $72 each. So for 2 m/c you're looking at about $145.
http://www.wilwood.com/Pedals/PedalList.aspx
Those are pedal assemblies, $120 for a dual m/c mounting setup. So then you're looking at a total cost of around $260 for the master cylinders AND pedal assembly to run a dual setup. And that's for high end, high quality aftermarket stuff. In fact those Wilwood parts I just listed are what you'll find on nearly every single Nextel Cup Car in the country(and many other race cars as well). And the remote adjuster is only another $52.
That's a lot cheaper than a good tandem m/c and a good booster. The stuff I listed is top of the line for quality, you'd have to get the cheapest most unreliable booster and m/c to beat that price. And also consider that boosters are "a dime a dozen" due to the economies of scale. They were put on millions of production cars, so costs from mass production is on their side, and they're still on average more expensive. And then you still need to add in the cost of a pressure reduction device as well, which a balance bar assembly doesn't need.
If dual m/c were as/more effective, companies would have done it a LONG time ago, because they're MUCH cheaper, especially if mass produced. But they didn't, because the braking requirements to low speed and light braking require different bias than high speed and heavy braking.
A lot of newer performance and luxury cars are actually going to electronically controlled brake biasing. They use different systems, some have an arm attached to the rear axle/suspension so as the suspension moves up and down from loading and unloading, it calculates effective tire loading and alters rear system pressure to compensate. Others actually use ABS sensors to determine how much slip exists in the tires from front to rear and adjusts bias base on actual wheel slip. But in all cases they're altering rear line pressure continuously across the whole range of conditions, not providing a static built in pressure ratio like a balance bar assembly does.
But the point is that a street car needs different biasing requirements than what a balance bar setup can deliver. Under maximum braking a balance bar setup is the superior setup, which is why it's on nearly every race car out there(where it's allowed). But street cars operate not only under maximum braking, but minimal braking and everything in between. A balance bar setup can provide the most effective biasing under 1 braking condition, but it's less than optimal under all other conditions. A hydraulic reduction type device(used on every production car on the planet) can provide very effective biasing across the entire range of conditions, but can't provide optimal biasing under any 1 condition. It's different systems for different requirements.
A dual m/c setup with a balance bar on the street has the potential to be extremely dangerous. While you may have a setup that is less than optimal under some conditions but has no major issues, balance bar setups on the street have the potential to create a brake system that's highly imbalanced in certain conditions. If you end up in a situation where you're doing nearly all of your stopping with the front wheels, even a very minor variation in traction at the 2 front wheels can result in the car pulling violently to one side.
05-11-2010, 01:10 AM
#13
3rd Gear Member
Join Date: Apr 2008
Location:
Posts: 939
That's a very nice Tnadem MC you're using. Very high quality, very durable - probably about the best of it's type on the market. It's an upgraded version of the stock part. But, it's not a dual MC, and that's the focus of this discussion.
This is the MC I've been using for the last few years. It's two MC's, with a balance bar and mounting bracket. It's bolted up to a stock Mustang pedal box, using a shortened stock Mustang brake pedal, and an adjustable push rod.
If there are some situations where this is dangerous, I havn't found them yet. I'v driven everything from very hot track days to high mountain passes in snow and rain. The brakes are always well balanced, and easy to modulate. On the track I can out brake just about anything out there - including the ZO6's.
As for cost, if you can find a set up like mine for $120, I want to see it. I'll buy a spare or two just in case I might need it in the future. The cheapest I'v found is about $350.
As for traction issues, that was the point of anti-locks. If you're in a panic stop mode, and nearly all of the braking is in the front (as it almost always is), and you lose traction on one tire, you're hosed. Unless you can feel it and modulate the brakes quick enough, you're in the dirt. But all Mustangs without anti-locks are in the same boat. The type of MC employed has no bearing, the end result will be the same.
The advantage to a dual MC is the adjustability. On a bone stock Mustang, the brake system is well designed and (IMO) doesn't need any changes for the average driver. But once you start making significant changes in balance, power, or other brake components, you need a MC that can go with the changes. Tandems will get you pretty close. But duals will get you spot on.
If this part had been available when I was building my Cobra, I would have jumped on it in a heart beat.
So, I'll ask the same question: Do you actually own and drive a car with dual MC's?
This is the MC I've been using for the last few years. It's two MC's, with a balance bar and mounting bracket. It's bolted up to a stock Mustang pedal box, using a shortened stock Mustang brake pedal, and an adjustable push rod.
If there are some situations where this is dangerous, I havn't found them yet. I'v driven everything from very hot track days to high mountain passes in snow and rain. The brakes are always well balanced, and easy to modulate. On the track I can out brake just about anything out there - including the ZO6's.
As for cost, if you can find a set up like mine for $120, I want to see it. I'll buy a spare or two just in case I might need it in the future. The cheapest I'v found is about $350.
As for traction issues, that was the point of anti-locks. If you're in a panic stop mode, and nearly all of the braking is in the front (as it almost always is), and you lose traction on one tire, you're hosed. Unless you can feel it and modulate the brakes quick enough, you're in the dirt. But all Mustangs without anti-locks are in the same boat. The type of MC employed has no bearing, the end result will be the same.
The advantage to a dual MC is the adjustability. On a bone stock Mustang, the brake system is well designed and (IMO) doesn't need any changes for the average driver. But once you start making significant changes in balance, power, or other brake components, you need a MC that can go with the changes. Tandems will get you pretty close. But duals will get you spot on.
If this part had been available when I was building my Cobra, I would have jumped on it in a heart beat.
So, I'll ask the same question: Do you actually own and drive a car with dual MC's?
Last edited by .boB; 05-11-2010 at 01:14 AM.
05-11-2010, 09:51 AM
#14
Former Sponsor
Thread Starter
Join Date: May 2010
Location: NV
Posts: 54
The advantage to a dual MC is the adjustability. On a bone stock Mustang, the brake system is well designed and (IMO) doesn't need any changes for the average driver. But once you start making significant changes in balance, power, or other brake components, you need a MC that can go with the changes. Tandems will get you pretty close. But duals will get you spot on.
If this part had been available when I was building my Cobra, I would have jumped on it in a heart beat.
So, I'll ask the same question: Do you actually own and drive a car with dual MC's?
If this part had been available when I was building my Cobra, I would have jumped on it in a heart beat.
So, I'll ask the same question: Do you actually own and drive a car with dual MC's?
05-11-2010, 07:03 PM
#15
Former Sponsor
Thread Starter
Join Date: May 2010
Location: NV
Posts: 54
Tandem MC vs Dual Master Cylinder with Balance Bar
The purpose of this Dual Master Cylinder setup is to get rid of the booster that is does not work because the engine does not produce the require amount of vacuum to operate the booster effectively. Here is a link off HRU's website on booster pressure to assist you:
http://www.deanoshiro.com/brakes/bra...e.html#booster
Formula for Booster Pressure can be found here:
http://www.deanoshiro.com/brakes/bra...rmula_boosters
It takes about 1,000 psi to lock up your wheels, you have to have this 1k psi by the master cylinder alone or the combination of a booster/master cylinder. The only thing that stop you from using a 3/4" bore "Tandem MC" is the fluid demand of the calipers you are using. If you use a "Tandem MC" with to small of a bore you will have the pedal travel a long ways and might run out of brake fluid. If you put a large bore "Tandem MC" such as a 1 or 1-1/8 or even the 1-1/4 inch bore the pedal will be hard and will require a lot of foot pressure to stop the brakes.
To properly understand calipers here is a link that will assist you:
http://www.deanoshiro.com/brakes/bra....html#calipers
Here is a quick Formula on output pressure is different size master cylinders with a "6 to 1" pedal ratio. BEFORE you use this you need to calculate what you pedal ratio is. There are two types of brake pedals manual and power brake pedals. If you use the manual pedal with a booster/mc the brakes would be to sensitive; if you use the power pedal on without a booster the pedal will be to hard. Generally manual pedals are set up at 6.0 to 6.25 to 1 and power pedals are 5 to 1.
To calculate your pedal ratio use this formula:
http://www.deanoshiro.com/brakes/bra...ula_pedalratio
On GM car they put two holes in the pedal, one for manual (upper hole) and one for power boosters (lower hole). If you will notice the GM cars have the booster tipped up in front and the booster bracket it at an angle. The reason for this is to point the booster rod to the lower hole of the GM brake pedal, to produce the manual ratio of 5:1. The advantage easy to change from manual to power brakes. The disadvantage is little or no hood clearance because the MC is close to the bottom of the hood and your reservoir volume is reduced because the fluid is tipped at an angle.
FMC did it correctly by using two pedals. We all know what a pain it is in a 1967 Mustang to change to a power pedal. The 67 was the first year of this design so the upper bracket mount was not drill for both the manual and power pedal. Early cars only had the manual hole. Now you know why your booster master combination site level in a FMC vs GMC.
Mustangs all have limited engine compartment space because of the shock towers and 428 even less. Now how many of us are running stock camshafts? How many have over 18 inches of vacuum to run a booster?
Ok, no vacuum so the booster does not good. Use a 7/8" or 1" master cylinder to get the pressure up. You have 764 and 998 psi with a 6:1 ratio pedal. Formula can be found here: http://www.deanoshiro.com/brakes/bra...mla_mcpressure
Your advantage vs disadvantage is purely physics and math (assumptions: 6:1 pedal ratio, 100 psi applied foot pressure) :
1. A 1 inch MC manually has output pressure is 764 in order to lock up the brake you have to apply about 130 pounds of foot pressure to the pedal to produce 1,000 psi. Not very much for someone 250 lbs and 6-2 but what about the wife that is 110 lbs and 5-2? Or you 16 year old daughter that begged to take your car to the prom?
2. A 7/8 inch MC has a 998 psi, and you only have to apply 100 pounds to your pedal to lock up the brakes, GREAT! The disadvantage is pedal travel. When you pads are brand new with ZERO wear, the pedal will travel 130% further than the 1 inch master cylinder. Who cares? ..... the guy road racing and the guy that has 10k miles on his car with the pads almost wore down.
Unless you have actually raced (road race, auto cross, hill climb, rally.....) a car, the hardest thing to do is braking and shifting in a corner. A pedal that travels to far complicates having to use the "heal and toe" method of brake/gas/clutch, almost impossible with a long stroke pedal. I am sure the racer's reading this can relate to braking comparison of new pads vs worn out pads. Much easier with new pads because of the pedal travel.
As your pads wear out with the Tandem MC setup your pedal travels further, until you have no pedal or not enough brake fluid. This is no problem for the more knowledgeable muscle car owner, he know what the limits of his system is. The same knowledgeable owners forget that they are the smaller percentage of muscle car owners. You guys are luck enough to read and understand the Forum.
This is the most over looked factor when sizing your brake master cylinder effect pad use and safety. Piston travel and pad thickness is directly related to the MC bore size. For more information on calculating volume of master cylinder go to: http://www.deanoshiro.com/brakes/bra...rmula_mcvolume
The advantage of the Dual Master cylinder is with a 3/4" bore the output pressure is 1400 psi and there is no wasted energy when using a balance bar. This this the part I have trouble explaining to you, because I do not have an Engineering degree so I can not explain it in the correct Physics Terminology. I would hope you engineers can jump right in and do it for me. This is a copy of a link from a brake article on the internet and I quote,
http://www.deanoshiro.com/brakes/bra...le.html#dualmc
........."There are major advantages to using dual master cylinders: (1) Smaller diameter master cylinders can be used to increase output pressure. The design allows the application of two master cylinders being applied at the same, thereby doubling the volume output. Because of this high pressure output you will not need a vacuum booster. If you are running any type of camshaft, chances are you do not have enough vacuum to run the booster anyway. (2) The balance bar eliminates the use of a proportional valve and gives you the optional remote adjustment. (3) The remote fill applications deletes the need for residual valve normally used when the reservoirs are lower than the calipers.
When calculating the output pressure of each master cylinder you can not say that applied pressure is “shared” equally between the two (2) master cylinders. If the two master cylinders did not have a balance bar between them and the application of force was always equally distributed this statement would be true. The balance bar allows the applied pressure to be distributed unequally.
Example:
6:1 ratio pedal assembly
¾" master cylinders
Applied force of 100 pounds with your foot
The formula shows that this combination produces 1359 psi, however if you apply the 100 pounds of force to both of them equally it will only produce 50 percent or 679.5 psi.
What the balance bar allows you to do is apply 65% of the force to the front and 35% to the rear so the actual output pressures would be 883 & 475 psi.
This is how you are able to obtain maximum braking with the same amount of applied force. When you are using a tandem master cylinder (OEM type inline bore) the output pressure is equal in both ports and the only way to reduce the pressure to the rear braking system is through metering (distribution block, combination valve or engineering in the master cylinder) or proportional valve. This works fine when you have more than enough pressure with a power booster but when you are using a manual master cylinder this energy is “wasted”.
The easiest way to test this "wasted energy" is to apply 100 uniform pounds of pressure to a 6:1 pedal ratio and measure the pressure at the front calipers and the rear calipers with a pressure gauge. You will find that you will not have 763 psi you will have a reduced amount directly related to your proportioning or reduced pressure in the rear. If you reduce the pressure in the rear by 15% the out pressure in the front system will only have 648 psi at the gauge. The 648 psi is not taking into account "Friction Lost". Friction Lost is the amount of pressure lost from length of travel and the size of the piping.
The only way to know the effective actual output pressure of your system with a proportional valve or distribution block installed is to measure it with a pressure gauge when using a Tandem MC setup. You get 100% when you do not have this restriction on dual master cylinders. So how many pounds are you actually pushing with your foot when you use a Tandem MC?
The only disadvantage is higher cost..... but what is your car worth? what is your life worth? Mine is worth more than $350.00
For all the Naysayers, everybody has there own preferences, priorities, driving styles and disposable income (for our babies i.e. cars). Just give a formula or Physics reason why a Tandem MC works better than a Dual MC setup. FYI you can look in "Handbook of Physics" by Condon & Odishaw for any Physics rebuttal you might have. To an Engineer give him Physics and Math or give him a black and white answer, if you can't prove it on paper he won't believe you.
This setup is not for everybody, it is only another solution to no or little vacuum on the muscle cars we are building today. We did not have the horse power or speed 10, 20 or 30 years ago, so we did not need as much braking as we do now. With today's technology the sky is the limit and the only thing holding us from going faster is the tires, suspension and brakes not so much the engines. I do not like band-aids like hydro-booster and vacuum canister/pumps. Just more things to go wrong.
I was hoping that I would not have to go into this much detail and I am sure I lost a few on the way. I guess if you got this far you have taken the time to read and digest this. Someday it may save someones life.
MrGorilla
http://www.deanoshiro.com/brakes/bra...e.html#booster
Formula for Booster Pressure can be found here:
http://www.deanoshiro.com/brakes/bra...rmula_boosters
It takes about 1,000 psi to lock up your wheels, you have to have this 1k psi by the master cylinder alone or the combination of a booster/master cylinder. The only thing that stop you from using a 3/4" bore "Tandem MC" is the fluid demand of the calipers you are using. If you use a "Tandem MC" with to small of a bore you will have the pedal travel a long ways and might run out of brake fluid. If you put a large bore "Tandem MC" such as a 1 or 1-1/8 or even the 1-1/4 inch bore the pedal will be hard and will require a lot of foot pressure to stop the brakes.
To properly understand calipers here is a link that will assist you:
http://www.deanoshiro.com/brakes/bra....html#calipers
Here is a quick Formula on output pressure is different size master cylinders with a "6 to 1" pedal ratio. BEFORE you use this you need to calculate what you pedal ratio is. There are two types of brake pedals manual and power brake pedals. If you use the manual pedal with a booster/mc the brakes would be to sensitive; if you use the power pedal on without a booster the pedal will be to hard. Generally manual pedals are set up at 6.0 to 6.25 to 1 and power pedals are 5 to 1.
To calculate your pedal ratio use this formula:
http://www.deanoshiro.com/brakes/bra...ula_pedalratio
On GM car they put two holes in the pedal, one for manual (upper hole) and one for power boosters (lower hole). If you will notice the GM cars have the booster tipped up in front and the booster bracket it at an angle. The reason for this is to point the booster rod to the lower hole of the GM brake pedal, to produce the manual ratio of 5:1. The advantage easy to change from manual to power brakes. The disadvantage is little or no hood clearance because the MC is close to the bottom of the hood and your reservoir volume is reduced because the fluid is tipped at an angle.
FMC did it correctly by using two pedals. We all know what a pain it is in a 1967 Mustang to change to a power pedal. The 67 was the first year of this design so the upper bracket mount was not drill for both the manual and power pedal. Early cars only had the manual hole. Now you know why your booster master combination site level in a FMC vs GMC.
Mustangs all have limited engine compartment space because of the shock towers and 428 even less. Now how many of us are running stock camshafts? How many have over 18 inches of vacuum to run a booster?
Ok, no vacuum so the booster does not good. Use a 7/8" or 1" master cylinder to get the pressure up. You have 764 and 998 psi with a 6:1 ratio pedal. Formula can be found here: http://www.deanoshiro.com/brakes/bra...mla_mcpressure
Your advantage vs disadvantage is purely physics and math (assumptions: 6:1 pedal ratio, 100 psi applied foot pressure) :
1. A 1 inch MC manually has output pressure is 764 in order to lock up the brake you have to apply about 130 pounds of foot pressure to the pedal to produce 1,000 psi. Not very much for someone 250 lbs and 6-2 but what about the wife that is 110 lbs and 5-2? Or you 16 year old daughter that begged to take your car to the prom?
2. A 7/8 inch MC has a 998 psi, and you only have to apply 100 pounds to your pedal to lock up the brakes, GREAT! The disadvantage is pedal travel. When you pads are brand new with ZERO wear, the pedal will travel 130% further than the 1 inch master cylinder. Who cares? ..... the guy road racing and the guy that has 10k miles on his car with the pads almost wore down.
Unless you have actually raced (road race, auto cross, hill climb, rally.....) a car, the hardest thing to do is braking and shifting in a corner. A pedal that travels to far complicates having to use the "heal and toe" method of brake/gas/clutch, almost impossible with a long stroke pedal. I am sure the racer's reading this can relate to braking comparison of new pads vs worn out pads. Much easier with new pads because of the pedal travel.
As your pads wear out with the Tandem MC setup your pedal travels further, until you have no pedal or not enough brake fluid. This is no problem for the more knowledgeable muscle car owner, he know what the limits of his system is. The same knowledgeable owners forget that they are the smaller percentage of muscle car owners. You guys are luck enough to read and understand the Forum.
This is the most over looked factor when sizing your brake master cylinder effect pad use and safety. Piston travel and pad thickness is directly related to the MC bore size. For more information on calculating volume of master cylinder go to: http://www.deanoshiro.com/brakes/bra...rmula_mcvolume
The advantage of the Dual Master cylinder is with a 3/4" bore the output pressure is 1400 psi and there is no wasted energy when using a balance bar. This this the part I have trouble explaining to you, because I do not have an Engineering degree so I can not explain it in the correct Physics Terminology. I would hope you engineers can jump right in and do it for me. This is a copy of a link from a brake article on the internet and I quote,
http://www.deanoshiro.com/brakes/bra...le.html#dualmc
........."There are major advantages to using dual master cylinders: (1) Smaller diameter master cylinders can be used to increase output pressure. The design allows the application of two master cylinders being applied at the same, thereby doubling the volume output. Because of this high pressure output you will not need a vacuum booster. If you are running any type of camshaft, chances are you do not have enough vacuum to run the booster anyway. (2) The balance bar eliminates the use of a proportional valve and gives you the optional remote adjustment. (3) The remote fill applications deletes the need for residual valve normally used when the reservoirs are lower than the calipers.
When calculating the output pressure of each master cylinder you can not say that applied pressure is “shared” equally between the two (2) master cylinders. If the two master cylinders did not have a balance bar between them and the application of force was always equally distributed this statement would be true. The balance bar allows the applied pressure to be distributed unequally.
Example:
6:1 ratio pedal assembly
¾" master cylinders
Applied force of 100 pounds with your foot
The formula shows that this combination produces 1359 psi, however if you apply the 100 pounds of force to both of them equally it will only produce 50 percent or 679.5 psi.
What the balance bar allows you to do is apply 65% of the force to the front and 35% to the rear so the actual output pressures would be 883 & 475 psi.
This is how you are able to obtain maximum braking with the same amount of applied force. When you are using a tandem master cylinder (OEM type inline bore) the output pressure is equal in both ports and the only way to reduce the pressure to the rear braking system is through metering (distribution block, combination valve or engineering in the master cylinder) or proportional valve. This works fine when you have more than enough pressure with a power booster but when you are using a manual master cylinder this energy is “wasted”.
The easiest way to test this "wasted energy" is to apply 100 uniform pounds of pressure to a 6:1 pedal ratio and measure the pressure at the front calipers and the rear calipers with a pressure gauge. You will find that you will not have 763 psi you will have a reduced amount directly related to your proportioning or reduced pressure in the rear. If you reduce the pressure in the rear by 15% the out pressure in the front system will only have 648 psi at the gauge. The 648 psi is not taking into account "Friction Lost". Friction Lost is the amount of pressure lost from length of travel and the size of the piping.
The only way to know the effective actual output pressure of your system with a proportional valve or distribution block installed is to measure it with a pressure gauge when using a Tandem MC setup. You get 100% when you do not have this restriction on dual master cylinders. So how many pounds are you actually pushing with your foot when you use a Tandem MC?
The only disadvantage is higher cost..... but what is your car worth? what is your life worth? Mine is worth more than $350.00
For all the Naysayers, everybody has there own preferences, priorities, driving styles and disposable income (for our babies i.e. cars). Just give a formula or Physics reason why a Tandem MC works better than a Dual MC setup. FYI you can look in "Handbook of Physics" by Condon & Odishaw for any Physics rebuttal you might have. To an Engineer give him Physics and Math or give him a black and white answer, if you can't prove it on paper he won't believe you.
This setup is not for everybody, it is only another solution to no or little vacuum on the muscle cars we are building today. We did not have the horse power or speed 10, 20 or 30 years ago, so we did not need as much braking as we do now. With today's technology the sky is the limit and the only thing holding us from going faster is the tires, suspension and brakes not so much the engines. I do not like band-aids like hydro-booster and vacuum canister/pumps. Just more things to go wrong.
I was hoping that I would not have to go into this much detail and I am sure I lost a few on the way. I guess if you got this far you have taken the time to read and digest this. Someday it may save someones life.
MrGorilla
Last edited by Gorilla Performance; 05-12-2010 at 02:51 AM.
05-12-2010, 03:13 AM
#16
6th Gear Member
Join Date: Apr 2007
Location: California
Posts: 10,468
ABS was developed entirely for the purpose of giving a vehicle the ability to steer in a panic stop. Most people lock the brakes without ABS, and when they do the car can't steer. ABS prevents the brakes from being locked 100% of the time and allows you to steer, even though the vehicle understeers due to an excessive slip angle. It's for idiots who don't know how to use their brakes and need to swerve.
Yes I have driven cars with dual m/c, they work fine, I never said they didn't. The point I was making is that a balance bar setup has it's place, but it's not in a street car. I don't have a balance bar dual m/c setup in my STREET CAR because they are not intended for use in street cars. Which is why they are not in street cars.
As far as output pressures and pedal effort and all that crap, it's dependent on pedal ratio, yes, and master cylinder bore as well as the caliper volume needs and piston sizes. 2 smaller bore master cylinders could theoretically offer less pedal effort than a tandem master cylinder. Or they could offer more. Or the same. The total force exerted on each m/c piston is added together to create the total pedal force, which is then reduced based on the pedal ratio. It's entirely dependent on how the system is set up. Pedal effort is also dependent on pad surface area and compounds, caliper piston sizes etc. While smaller bores create more pressure, you move less volume so you're pedal travel increases if you have the same pedal ratio. If you then run a reduced pedal ratio to limit the travel of your foot you lose mechanical advantage and are back at square one.
Pressure required to lock a tire is entirely arbitrary and changes car to car based on multiple variables. Stickier tires needs more pressure to lock, lower coefficient of friction in the pads requires more pressure to lock, small pad surface area requires more pressure to lock, smaller caliper pistons requires more pressure to lock. Larger diameter wheels require more pressure to lock. A heavier car requires more pressure to lock.
And not all tandem m/c produce the same output pressure at both ports. They can use different internal piston sizes for the front and rear systems, and while it's rare, I have seen a few built that way. In that regard a tandem m/c could function much the same as a dual m/c does(however in that case the bias is not adjustable in the m/c itself). The primary problem with a tandem m/c is because of internal design limitations on the placement of the pistons, they have limited travel so you theoretically could run into a situation where you are unable to move the necessary volume for a certain system. That is very rare though and only occurs when a system is improperly designed. And designing them with enough throw results in an unnecessarily long m/c.
A tandem m/c has 2 pistons in it internally, so it functions much the same as dual m/c. In fact, a 6:1 pedal ratio with 2 m/c that were each 3/4" bore would have the EXACT SAME PEDAL EFFORT as a single tandem m/c with 2 3/4" pistons inside it. In both cases you're exerting the pedal effort across the surface area of 2 3/4" pistons, the only different is whether they are in line(tandem) or side by side(dual). The 2 systems just need a different design(generally). With a tandem you want smaller rear brakes and/or pressure reduction to the rear, and/or smaller rear caliper piston area. With a dual, much of your system balance is designed in the master cylinder size, pick a different size for each end of the car to get close, and fine tune with the balance bar.
And pad wear should not be an issue with a dual or tandem m/c. As the pads wear in extremely small increments, when the brake is released the reservoir fluid should "take up the slack". The pedal should feel the same when the pads are new as it does when they're worn down to the backing plate. If you're pedal is changing as the pads are wearing then something is wrong with your system.
In the end though the primary purpose of a dual m/c is to run a balance bar because it can be adjusted easily. If you can also run smaller bore m/c then you'll produce higher pressure and have reduced pedal effort, but you'll have to move the pedal farther to provide the same volume. That's assuming everything else stays the same. Set up with the right pedal ratio and you'll have an easy to operate system. But again, the primary purpose of a dual m/c setup is to run a balance bar for the adjustability, which as I've stated earlier is less than ideal for street use.
And incidentally, the tandem m/c I run is a "large" 1-1/16" bore. My pedal effort is about the same as a power brake system towards the "harder pedal" end of power brakes. Pedal effort decreases as the brakes heat up under racing conditions or hard street driving. I have more than enough room for extra pedal travel, and had to actually adjust the pedal location to account for the LACK of travel. If I were to switch to a tandem 7/8" bore unit, my pedal effort would be substantially lighter. At that point I'd be more concerned about losing modulation characteristics than I would about excessive pedal travel.
Yes, dual m/c work well, but a BALANCE BAR is not intended for use on the street. You can argue the advantages of a dual m/c setup all day long, and you'd probably be right. But the point I was making initially is that a balance bar setup does not provide the type of front-rear bias that a street car requires. If someone wants to convert to dual m/c for the ease of pedal effort on a street car, that's fine, as long as a hydraulic proportioning valve is used in the rear to provide the proper bias under a wide array of conditions a street car sees. But a balance bar only in a street car has the potential to create an uncontrollable car in some situations.
Yes I have driven cars with dual m/c, they work fine, I never said they didn't. The point I was making is that a balance bar setup has it's place, but it's not in a street car. I don't have a balance bar dual m/c setup in my STREET CAR because they are not intended for use in street cars. Which is why they are not in street cars.
As far as output pressures and pedal effort and all that crap, it's dependent on pedal ratio, yes, and master cylinder bore as well as the caliper volume needs and piston sizes. 2 smaller bore master cylinders could theoretically offer less pedal effort than a tandem master cylinder. Or they could offer more. Or the same. The total force exerted on each m/c piston is added together to create the total pedal force, which is then reduced based on the pedal ratio. It's entirely dependent on how the system is set up. Pedal effort is also dependent on pad surface area and compounds, caliper piston sizes etc. While smaller bores create more pressure, you move less volume so you're pedal travel increases if you have the same pedal ratio. If you then run a reduced pedal ratio to limit the travel of your foot you lose mechanical advantage and are back at square one.
Pressure required to lock a tire is entirely arbitrary and changes car to car based on multiple variables. Stickier tires needs more pressure to lock, lower coefficient of friction in the pads requires more pressure to lock, small pad surface area requires more pressure to lock, smaller caliper pistons requires more pressure to lock. Larger diameter wheels require more pressure to lock. A heavier car requires more pressure to lock.
And not all tandem m/c produce the same output pressure at both ports. They can use different internal piston sizes for the front and rear systems, and while it's rare, I have seen a few built that way. In that regard a tandem m/c could function much the same as a dual m/c does(however in that case the bias is not adjustable in the m/c itself). The primary problem with a tandem m/c is because of internal design limitations on the placement of the pistons, they have limited travel so you theoretically could run into a situation where you are unable to move the necessary volume for a certain system. That is very rare though and only occurs when a system is improperly designed. And designing them with enough throw results in an unnecessarily long m/c.
A tandem m/c has 2 pistons in it internally, so it functions much the same as dual m/c. In fact, a 6:1 pedal ratio with 2 m/c that were each 3/4" bore would have the EXACT SAME PEDAL EFFORT as a single tandem m/c with 2 3/4" pistons inside it. In both cases you're exerting the pedal effort across the surface area of 2 3/4" pistons, the only different is whether they are in line(tandem) or side by side(dual). The 2 systems just need a different design(generally). With a tandem you want smaller rear brakes and/or pressure reduction to the rear, and/or smaller rear caliper piston area. With a dual, much of your system balance is designed in the master cylinder size, pick a different size for each end of the car to get close, and fine tune with the balance bar.
And pad wear should not be an issue with a dual or tandem m/c. As the pads wear in extremely small increments, when the brake is released the reservoir fluid should "take up the slack". The pedal should feel the same when the pads are new as it does when they're worn down to the backing plate. If you're pedal is changing as the pads are wearing then something is wrong with your system.
In the end though the primary purpose of a dual m/c is to run a balance bar because it can be adjusted easily. If you can also run smaller bore m/c then you'll produce higher pressure and have reduced pedal effort, but you'll have to move the pedal farther to provide the same volume. That's assuming everything else stays the same. Set up with the right pedal ratio and you'll have an easy to operate system. But again, the primary purpose of a dual m/c setup is to run a balance bar for the adjustability, which as I've stated earlier is less than ideal for street use.
And incidentally, the tandem m/c I run is a "large" 1-1/16" bore. My pedal effort is about the same as a power brake system towards the "harder pedal" end of power brakes. Pedal effort decreases as the brakes heat up under racing conditions or hard street driving. I have more than enough room for extra pedal travel, and had to actually adjust the pedal location to account for the LACK of travel. If I were to switch to a tandem 7/8" bore unit, my pedal effort would be substantially lighter. At that point I'd be more concerned about losing modulation characteristics than I would about excessive pedal travel.
Yes, dual m/c work well, but a BALANCE BAR is not intended for use on the street. You can argue the advantages of a dual m/c setup all day long, and you'd probably be right. But the point I was making initially is that a balance bar setup does not provide the type of front-rear bias that a street car requires. If someone wants to convert to dual m/c for the ease of pedal effort on a street car, that's fine, as long as a hydraulic proportioning valve is used in the rear to provide the proper bias under a wide array of conditions a street car sees. But a balance bar only in a street car has the potential to create an uncontrollable car in some situations.
Last edited by 67mustang302; 05-12-2010 at 03:23 AM.
05-12-2010, 06:56 PM
#17
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Join Date: May 2010
Location: NV
Posts: 54
Answer: 67mustang302 Member
ABS was developed entirely for the purpose of giving a vehicle the ability to steer in a panic stop. Most people lock the brakes without ABS, and when they do the car can't steer. ABS prevents the brakes from being locked 100% of the time and allows you to steer, even though the vehicle understeers due to an excessive slip angle. It's for idiots who don't know how to use their brakes and need to swerve.
Yes I have driven cars with dual m/c, they work fine, I never said they didn't. The point I was making is that a balance bar setup has it's place, but it's not in a street car. I don't have a balance bar dual m/c setup in my STREET CAR because they are not intended for use in street cars. Which is why they are not in street cars.
"FOR OFF ROAD USE ONLY BEFORE OPERATING VEHICLE, TEST THE BRAKES UNDER CONTROLLED CONDITIONS. MAKE SEVERAL STOPS IN A SAFE AREA FROM LOW SPEEDS AND GRADUALLY WORK UP TO RACING SPEEDS. DO NOT RACE ON UNTESTED BRAKES! ALWAYS UTILIZE SAFETY RESTRAINT SYSTEMS WHILE OPERATING VEHICLE. IMPORTANT READ DISCLAIMER OF WARRANTY INCLUDED IN THE KIT."
The above was copied from the front page of Wilwood instructions part number 140-4304. I think you said you have Wilwood's on your 67 Mustang.
As far as output pressures and pedal effort and all that crap, it's dependent on pedal ratio, yes, and master cylinder bore as well as the caliper volume needs and piston sizes. 2 smaller bore master cylinders could theoretically offer less pedal effort than a tandem master cylinder. Or they could offer more. Or the same. The total force exerted on each m/c piston is added together to create the total pedal force, which is then reduced based on the pedal ratio. It's entirely dependent on how the system is set up. Pedal effort is also dependent on pad surface area and compounds, caliper piston sizes etc. While smaller bores create more pressure, you move less volume so you're pedal travel increases if you have the same pedal ratio. If you then run a reduced pedal ratio to limit the travel of your foot you lose mechanical advantage and are back at square one.
Pressure required to lock a tire is entirely arbitrary and changes car to car based on multiple variables. Stickier tires needs more pressure to lock, lower coefficient of friction in the pads requires more pressure to lock, small pad surface area requires more pressure to lock, smaller caliper pistons requires more pressure to lock. Larger diameter wheels require more pressure to lock. A heavier car requires more pressure to lock.
And not all tandem m/c produce the same output pressure at both ports. They can use different internal piston sizes for the front and rear systems, and while it's rare, I have seen a few built that way. In that regard a tandem m/c could function much the same as a dual m/c does(however in that case the bias is not adjustable in the m/c itself). The primary problem with a tandem m/c is because of internal design limitations on the placement of the pistons, they have limited travel so you theoretically could run into a situation where you are unable to move the necessary volume for a certain system. That is very rare though and only occurs when a system is improperly designed. And designing them with enough throw results in an unnecessarily long m/c.
"The easiest way to test this "wasted energy" is to apply 100 uniform pounds of pressure to a 6:1 pedal ratio and measure the pressure at the front calipers and the rear calipers with a pressure gauge. You will find that you will not have 763 psi you will have a reduced amount directly related to your proportioning or reduced pressure in the rear. If you reduce the pressure in the rear by 15% the out pressure in the front system will only have 648 psi at the gauge. The 648 psi is not taking into account "Friction Lost". Friction Lost is the amount of pressure lost from length of travel and the size of the piping."
Oh, I almost forgot to mention, I use to design irrigation systems for golf courses and was certified by I.A. (Irrigation Association) 15 years ago, so we don't need to debate friction lost. I don't have my card any more, but I can send you a picture of Ed Hunter (Hunter Industries... do a goggle on Edwin J. Hunter)
A tandem m/c has 2 pistons in it internally, so it functions much the same as dual m/c. In fact, a 6:1 pedal ratio with 2 m/c that were each 3/4" bore would have the EXACT SAME PEDAL EFFORT as a single tandem m/c with 2 3/4" pistons inside it. In both cases you're exerting the pedal effort across the surface area of 2 3/4" pistons, the only different is whether they are in line(tandem) or side by side(dual). The 2 systems just need a different design(generally). With a tandem you want smaller rear brakes and/or pressure reduction to the rear, and/or smaller rear caliper piston area. With a dual, much of your system balance is designed in the master cylinder size, pick a different size for each end of the car to get close, and fine tune with the balance bar.
And pad wear should not be an issue with a dual or tandem m/c. As the pads wear in extremely small increments, when the brake is released the reservoir fluid should "take up the slack". The pedal should feel the same when the pads are new as it does when they're worn down to the backing plate. If you're pedal is changing as the pads are wearing then something is wrong with your system.
In the end though the primary purpose of a dual m/c is to run a balance bar because it can be adjusted easily. If you can also run smaller bore m/c then you'll produce higher pressure and have reduced pedal effort, but you'll have to move the pedal farther to provide the same volume. That's assuming everything else stays the same. Set up with the right pedal ratio and you'll have an easy to operate system. But again, the primary purpose of a dual m/c setup is to run a balance bar for the adjustability, which as I've stated earlier is less than ideal for street use.
And incidentally, the tandem m/c I run is a "large" 1-1/16" bore. My pedal effort is about the same as a power brake system towards the "harder pedal" end of power brakes. Pedal effort decreases as the brakes heat up under racing conditions or hard street driving. I have more than enough room for extra pedal travel, and had to actually adjust the pedal location to account for the LACK of travel. If I were to switch to a tandem 7/8" bore unit, my pedal effort would be substantially lighter. At that point I'd be more concerned about losing modulation characteristics than I would about excessive pedal travel.
Yes, dual m/c work well, but a BALANCE BAR is not intended for use on the street. You can argue the advantages of a dual m/c setup all day long, and you'd probably be right. But the point I was making initially is that a balance bar setup does not provide the type of front-rear bias that a street car requires. If someone wants to convert to dual m/c for the ease of pedal effort on a street car, that's fine, as long as a hydraulic proportioning valve is used in the rear to provide the proper bias under a wide array of conditions a street car sees. But a balance bar only in a street car has the potential to create an uncontrollable car in some situations.
In the end though the primary purpose of a dual m/c is to run a balance bar because it can be adjusted easily. If you can also run smaller bore m/c then you'll produce higher pressure and have reduced pedal effort, but you'll have to move the pedal farther to provide the same volume. That's assuming everything else stays the same. Set up with the right pedal ratio and you'll have an easy to operate system. But again, the primary purpose of a dual m/c setup is to run a balance bar for the adjustability, which as I've stated earlier is less than ideal for street use.
And incidentally, the tandem m/c I run is a "large" 1-1/16" bore. My pedal effort is about the same as a power brake system towards the "harder pedal" end of power brakes. Pedal effort decreases as the brakes heat up under racing conditions or hard street driving. I have more than enough room for extra pedal travel, and had to actually adjust the pedal location to account for the LACK of travel. If I were to switch to a tandem 7/8" bore unit, my pedal effort would be substantially lighter. At that point I'd be more concerned about losing modulation characteristics than I would about excessive pedal travel.
Yes, dual m/c work well, but a BALANCE BAR is not intended for use on the street. You can argue the advantages of a dual m/c setup all day long, and you'd probably be right. But the point I was making initially is that a balance bar setup does not provide the type of front-rear bias that a street car requires. If someone wants to convert to dual m/c for the ease of pedal effort on a street car, that's fine, as long as a hydraulic proportioning valve is used in the rear to provide the proper bias under a wide array of conditions a street car sees. But a balance bar only in a street car has the potential to create an uncontrollable car in some situations.
....See my previous thread.... If you have a 1-1/16 inch master I do not think you can skid your front tires on dry pavement.
Last edited by Gorilla Performance; 05-16-2010 at 11:45 AM.
05-12-2010, 08:50 PM
#18
6th Gear Member
Join Date: Apr 2007
Location: California
Posts: 10,468
You still absolutely fail to address the original issue. The only single issue I've disagreed with you on in fact. You're trying to go off on 7 other different topics by posting information that may or may not be correct. I'm not even disagreeing with you on the other issues, and while some of your information may be slightly incorrect on a few issues, it's for the most part accurate.
MY POINT WAS THAT JUST A BALANCE BAR CAN ONLY SET BRAKE BIAS AT 1 SINGLE STATIC SETTING FOR FRONT TO REAR, WHICH CAN ONLY ACCOUNT FOR IDEAL BIASING UNDER MAXIMUM BRAKING CONDITIONS. IT CAN NOT PROVIDE A DIFFERENT BIAS UNDER LOW EFFORT BRAKING IN WHICH THERE IS LESS LOAD TRANSFER TO THE FRONT, REQUIRING GREATER REAR BIAS TO ACCOUNT FOR THE INCREASED REAR WHEEL TRACTION DUE TO HIGHER TIRE LOADING AS A RESULT OF THE REDUCED LOAD TRANSFER RELATIVE TO MAXIMUM BRAKING EFFORT.
Is that clear enough? That's why production vehicles for street use use a hydraulic type rear bias controller. It sets both a "knee point" and a bias ratio. The knee point is the point at which rear biasing BEGINS. Under light-medium braking the proportioning valve does not alter brake bias and provides 50/50 pressure balance front to rear. Combined with slightly reduced braking capability in the rear it results in a close to optimal bias to take advantage of the traction at all 4 wheels. As the braking effort increases and load transfer shifts traction to the front of the vehicle and reduces traction at the rear, the prop valve hits the knee point and begins to provide a pressure bias towards the front to account for the front wheels doing a greater amount of work than the rear.
A balance bar can NOT do that, it only has 1 single bias setting that begins from the instant you generate any brake pressure all the way to maximum. The pressure ratio is constant, or static. A hydraulic proportioning valve results in a variable bias to try to account for a wider range of braking conditions.
As far as Wilwood's disclaimer of for racing use only, it's simply for liability. By stating that all parts are for racing use only and the purchaser assumes ALL liability for anything that happens, Wilwood can not be sued by someone who uses their products and has a problem. MANY manufacturers state that, so they can clearly release liability and not provide room for the consumer to assume anything about the product.
And yes, my 1-1/16" m/c will lock my tires rather easily on dry pavement. And after 1-2 hard stops with some heat in the pads, it becomes VERY easy to lock the tires on dry pavement.
But to remain on track, my ENTIRE POINT originally is that a balance bar assembly while superior for controlling bias under maximum braking, can not change to a different bias to account for reduced front tire loading during light-medium braking. That can POTENTIALLY lead to a car with an unbalanced brake system at light-medium braking, and depending on the conditions and the severity of the imbalance, it could lead to a loss of vehicle control. That is EXACTLY why that setup, even though much cheaper and far more reliable, is NOT used any any production car on Earth.
At the very least it will accelerate the wear of the front pads by under utilizing the rear brakes in normal driving. And while that may be acceptable for a weekend warrior that doesn't spend a lot of time driving around, on a daily driven street car it is an area of concern.
MY POINT WAS THAT JUST A BALANCE BAR CAN ONLY SET BRAKE BIAS AT 1 SINGLE STATIC SETTING FOR FRONT TO REAR, WHICH CAN ONLY ACCOUNT FOR IDEAL BIASING UNDER MAXIMUM BRAKING CONDITIONS. IT CAN NOT PROVIDE A DIFFERENT BIAS UNDER LOW EFFORT BRAKING IN WHICH THERE IS LESS LOAD TRANSFER TO THE FRONT, REQUIRING GREATER REAR BIAS TO ACCOUNT FOR THE INCREASED REAR WHEEL TRACTION DUE TO HIGHER TIRE LOADING AS A RESULT OF THE REDUCED LOAD TRANSFER RELATIVE TO MAXIMUM BRAKING EFFORT.
Is that clear enough? That's why production vehicles for street use use a hydraulic type rear bias controller. It sets both a "knee point" and a bias ratio. The knee point is the point at which rear biasing BEGINS. Under light-medium braking the proportioning valve does not alter brake bias and provides 50/50 pressure balance front to rear. Combined with slightly reduced braking capability in the rear it results in a close to optimal bias to take advantage of the traction at all 4 wheels. As the braking effort increases and load transfer shifts traction to the front of the vehicle and reduces traction at the rear, the prop valve hits the knee point and begins to provide a pressure bias towards the front to account for the front wheels doing a greater amount of work than the rear.
A balance bar can NOT do that, it only has 1 single bias setting that begins from the instant you generate any brake pressure all the way to maximum. The pressure ratio is constant, or static. A hydraulic proportioning valve results in a variable bias to try to account for a wider range of braking conditions.
As far as Wilwood's disclaimer of for racing use only, it's simply for liability. By stating that all parts are for racing use only and the purchaser assumes ALL liability for anything that happens, Wilwood can not be sued by someone who uses their products and has a problem. MANY manufacturers state that, so they can clearly release liability and not provide room for the consumer to assume anything about the product.
And yes, my 1-1/16" m/c will lock my tires rather easily on dry pavement. And after 1-2 hard stops with some heat in the pads, it becomes VERY easy to lock the tires on dry pavement.
But to remain on track, my ENTIRE POINT originally is that a balance bar assembly while superior for controlling bias under maximum braking, can not change to a different bias to account for reduced front tire loading during light-medium braking. That can POTENTIALLY lead to a car with an unbalanced brake system at light-medium braking, and depending on the conditions and the severity of the imbalance, it could lead to a loss of vehicle control. That is EXACTLY why that setup, even though much cheaper and far more reliable, is NOT used any any production car on Earth.
At the very least it will accelerate the wear of the front pads by under utilizing the rear brakes in normal driving. And while that may be acceptable for a weekend warrior that doesn't spend a lot of time driving around, on a daily driven street car it is an area of concern.
05-12-2010, 10:37 PM
#19
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Thread Starter
Join Date: May 2010
Location: NV
Posts: 54
I think you are making it quite apparent you have Never used a Balance Bar Assembly. We have only explained this 4 different ways. I was just trying to educate you and not do a debate.
Last edited by Gorilla Performance; 05-15-2010 at 03:18 PM.
05-13-2010, 11:36 AM
#20
6th Gear Member
Join Date: Aug 2007
Location: Elk Grove, CA
Posts: 5,896
I find it amusing when people ignore physics and logical arguments in favor of "have you ever tried it?" Either dispute his argument, or move on. Whether or not he has actually used one, his point is still valid. Balance bar setups are simply not designed for a primarily street-driven car, hence why there are no production cars that use them.
Sure, it'd be a great setup for a track toy that only sees occasional street use, but I wouldn't put one in my street car for the reasons 67mustang302 has provided.
Sure, it'd be a great setup for a track toy that only sees occasional street use, but I wouldn't put one in my street car for the reasons 67mustang302 has provided.