Gorilla Performance Bal-Bar Balance Bar Dual MC's NO BOOSTER Required
09-28-2010, 06:49 AM
#61
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
I think something is missing ↑.
While it is true that a balance bar mechanism can fine-tune the front:rear bias for a particular situation, it will still result in a vehicle whose braking is biased a little too rearward at decelerations greater than the design point, and a little too forward at decelerations that are lower. IOW, set it up and tune it for performance street rubber and you'll still overbrake and lock the rears if you put same-size R-compound or maybe even the better "Street Touring" autocross tires on the same car. It is this situation where the braking deceleration is considered to be an independent variable over a fairly wide range that a prop valve seeks to remedy. A prop valve isn't a perfect solution either, but for the overall spectrum of braking events it will keep the balance of braking effort closer to ideal than any system that has only a single setting can.
I also think what you're getting at is more about Electronic Brake Distribution - EBD is a relatively recent development piggybacked on ABS rather than being ABS per se. More here. Done properly, this can apparently account for variations in vehicle loading and even vary the proportioning while any given braking event is in the process of developing.
You're apparently in an unusually fortunate situation, where another driver of the same car is willing to tinker with brake bias. However, I hope that the endpoints of your 20% range are somehow fixed to be repeatable with dead-nuts accuracy. If not, taking "about 20% out" and returning it could cause some "creep" if what you consistently take out ends up being 18% or 19% and then 21% or 22% is what you tend to put back in. Don't assume that your accuracy will be identical in the opposite directions. Or if two drivers each take 20% out and driver #2 is unaware that driver #1 has already done so. Etc. This has to be as idiot-proof as you can possibly make it, as in hard mechanical stops. Even then, you're adding the burden of mandatory checking it every time you get into the car just to make sure that it's at the appropriate setting.
Edit - this is actually slightly more complex than linear math, given that tire grip varies as something like the 0.7 power of vertical load (10% more vertical load buys you just under 7% more horizontal force, so your effective "mu" drops slightly as tire loading goes up).
Norm
While it is true that a balance bar mechanism can fine-tune the front:rear bias for a particular situation, it will still result in a vehicle whose braking is biased a little too rearward at decelerations greater than the design point, and a little too forward at decelerations that are lower. IOW, set it up and tune it for performance street rubber and you'll still overbrake and lock the rears if you put same-size R-compound or maybe even the better "Street Touring" autocross tires on the same car. It is this situation where the braking deceleration is considered to be an independent variable over a fairly wide range that a prop valve seeks to remedy. A prop valve isn't a perfect solution either, but for the overall spectrum of braking events it will keep the balance of braking effort closer to ideal than any system that has only a single setting can.
I also think what you're getting at is more about Electronic Brake Distribution - EBD is a relatively recent development piggybacked on ABS rather than being ABS per se. More here. Done properly, this can apparently account for variations in vehicle loading and even vary the proportioning while any given braking event is in the process of developing.
You're apparently in an unusually fortunate situation, where another driver of the same car is willing to tinker with brake bias. However, I hope that the endpoints of your 20% range are somehow fixed to be repeatable with dead-nuts accuracy. If not, taking "about 20% out" and returning it could cause some "creep" if what you consistently take out ends up being 18% or 19% and then 21% or 22% is what you tend to put back in. Don't assume that your accuracy will be identical in the opposite directions. Or if two drivers each take 20% out and driver #2 is unaware that driver #1 has already done so. Etc. This has to be as idiot-proof as you can possibly make it, as in hard mechanical stops. Even then, you're adding the burden of mandatory checking it every time you get into the car just to make sure that it's at the appropriate setting.
Edit - this is actually slightly more complex than linear math, given that tire grip varies as something like the 0.7 power of vertical load (10% more vertical load buys you just under 7% more horizontal force, so your effective "mu" drops slightly as tire loading goes up).
Norm
Last edited by Norm Peterson; 09-28-2010 at 07:36 AM.
09-29-2010, 10:53 AM
#62
Join Date: May 2006
Location: WA
Posts: 6
Some Human Being
Once I got the CNC made setup, it was immediately apparent that the balance bar tube was made wrong, and would not accept either pushrod I had. The stock Ford clip retained manual brake pushrod, or the SSBC's adjustable one I ordered. So, I was very frustrated by the fact that I just dropped $350 big ones and I still was forced to make a new tube just to hook up the brake pedal. Come on guys/gals, how hard is it to tap the damn tube for 3/8-24? While I was at it, for adjustability, I did shorten that tube to 1.600 from 2.125 as well. I also hard-anodized the bracket, as they should have, and hard-chromed my hand-made sleeve. (Basic common sense things engineers do for durability.) CNC inc, has a nice bracket, nice pinned threaded spherical rod ends, and a nice selection of master cylinders. But that's it, your on your own for the rest. Their attention to detail, and customer service frankly suck and conversations with them are unproductive at best. At any rate, my instincts told me I didn't need residual pressure valves, but they insisted I did. So, I bought them anyway, because I thought for sure they couldn't CAUSE trouble. But, I was under the impression from the photos they sent me that the residual pressure valves were an option that were installed INSIDE the damn master cylinders when you ordered them. I didn't realize they are a needlessly long sloppy addition to the front, making the already a bit unwieldy CNC setup, even bigger. So, I removed them with no change in pedal feel whatsoever. The car's pedal feel is similar to a "hard" modern power brake tandem master cylinder equipped car. Bias is of course adjustable from the cabin, so after a very short bit of instruction, my wife learned to change it based on traction conditions. And she does. When it rains, she takes about 20% out of the rear and adds it to the front.
Since there was no room under the dash with your collisapible column, it might have beeen easier to just change steering columns. No you do not need resdiual valves, unless your master cylinder is "close" to the same height as the calipers. It is not going to hurt putting the residual valves in but you most likely don't need it.
Email me if you need additional help or questions.
09-29-2010, 11:00 AM
#63
Join Date: May 2006
Location: WA
Posts: 6
Hello Norm
Bottom line is the CNC system vs a Wilwood, Tilton, Coleman or Gorilla set up is limited becasue the sleeve is almost 5/8" to long, thereby restricting the amount of bias adjustment. This is not a problem if your system is within 10% of "perfect bias" before installing the CNC system.
09-30-2010, 11:54 AM
#64
Join Date: Jul 2010
Location: NY
Posts: 11
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.
So how many pounds are you actually pushing with your foot when you use a Tandem MC?[/FONT]
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.
So how many pounds are you actually pushing with your foot when you use a Tandem MC?[/FONT]
10-01-2010, 10:18 AM
#65
Join Date: May 2006
Location: WA
Posts: 6
Lock up the brakes
Any poundage stated in this thread is with a constant of 100 psi applied pressure. In order to have a answer to a formula you can only have 1 varible. So most formulas for output pressure will use a constant of 100 psi. In order to figure what the applied pressure to reach the 1000 psi your would have to use the 1000 psi for the constant.
http://www.deanoshiro.com/brakes/brakearticle.html
Here is the link for the brake article.
FYI for the Ford applications with 4 bolts holes on the upper brake pedal bracket has to be cut just below the two upper hole and tappered back to the pivot hole for the brake pedal.
Last edited by moonmr; 10-01-2010 at 10:24 AM.
01-11-2011, 06:02 PM
#66
Former Sponsor
Thread Starter
Join Date: May 2010
Location: NV
Posts: 54
Pictures of install with Clutch
Here are pictures of this system installed with juice clutch setup.
http://www.gorillaperformance.com/
Dual MCs with our juice clutch setup.
Side view
Top view
Inside View 1967 Under Dash
http://www.gorillaperformance.com/
Dual MCs with our juice clutch setup.
Side view
Top view
Inside View 1967 Under Dash
01-12-2011, 07:35 PM
#69
Join Date: Jul 2010
Location: NY
Posts: 11
Most systems take about 1,000 psi to lock up, and most square ring seal calipers from Wilwood have a warning do not exceed 1,200 psi.
Any poundage stated in this thread is with a constant of 100 psi applied pressure. In order to have a answer to a formula you can only have 1 varible. So most formulas for output pressure will use a constant of 100 psi. In order to figure what the applied pressure to reach the 1000 psi your would have to use the 1000 psi for the constant.
http://www.deanoshiro.com/brakes/brakearticle.html
Any poundage stated in this thread is with a constant of 100 psi applied pressure. In order to have a answer to a formula you can only have 1 varible. So most formulas for output pressure will use a constant of 100 psi. In order to figure what the applied pressure to reach the 1000 psi your would have to use the 1000 psi for the constant.
http://www.deanoshiro.com/brakes/brakearticle.html
Whereas I can haul my 540i down with my big toe. Nice light-effort brakes can make a heavy car like that feel light, and conversely a one-leg leg-press in my Mustang makes it feel less sports-car like. Even where the Mustang probably stops in a shorter distance.
I guess I was raised on the girly-man power brakes.
Last edited by gsxrken; 01-12-2011 at 07:36 PM. Reason: spelling
01-12-2011, 08:22 PM
#70
Former Sponsor
Thread Starter
Join Date: May 2010
Location: NV
Posts: 54
Your math is off
So I just figured out that with the 3/4" MCs, I would need to put 150 pounds into my manual pedal to get 1000PSI. That's a 6:1 pedal, 150 pounds force, and divided by .442 (the area of my 3/4" MC) = 2036. That gets divided by 2 b/c there's 2 MCs splitting that, so I'm at 1,018PSI per axle.
Whereas I can haul my 540i down with my big toe. Nice light-effort brakes can make a heavy car like that feel light, and conversely a one-leg leg-press in my Mustang makes it feel less sports-car like. Even where the Mustang probably stops in a shorter distance.
I guess I was raised on the girly-man power brakes.
Whereas I can haul my 540i down with my big toe. Nice light-effort brakes can make a heavy car like that feel light, and conversely a one-leg leg-press in my Mustang makes it feel less sports-car like. Even where the Mustang probably stops in a shorter distance.
I guess I was raised on the girly-man power brakes.
MrGorilla