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    Assemble a Bias Pedal Box

    Preamble:
    This is a work in progress, doen quickly to annot Matt as he is hard of learning so any errors please let me know and Ill update it.

    ===================

    Here is just a quick how to set up an Escort bias pedal box and a few explanations of why it’s done this way.

    First thing you should do is have a good look at the pedal box, familiarise yourself with the parts and how they all fit, you should notice that the pedal top is not central to the two master cylinder holes; the front master cylinder should be fitted to the hole that’s nearest the pedal and there is a good reason for this; as it already has some built in bias. In an Escort we only want about 20% of the braking force at the rear and in a stripped out race car maybe even less.

    Most common brake setups with disks all around use a 0.625 inch bore master cylinder on the front and a 0.7 or 0.75 on the rear (but this does depend on the actual size of the piston in the calliper or wheel cylinder too big and your brakes will be hard but with little effect, to small and you will have excessive pedal stroke but lots of power, most suppliers can advise on sizes for common callipers I will list some below soon) on an Escort Bias Box the master cylinder exerting the most pressure (smallest) will always go to the front, it’s a common misconception that the larger the master cylinder the more breaking power is achieved, it is in fact the complete opposite. Breaking power is achieved by 2 multiplications of force the first is mechanical and the second hydraulic:

    The pedal is the mechanical multiplier; the master cylinder rod is much nearer the pivot point that the pedal rubber where you apply the force, if we say the ratio of the pivots is 5:1 for every 1 lb of pressure that we apply to the pedal 5 lb of pressure is applied to the master cylinder pistons.
    The Bias bar is simply a mechanical divider this divides the mechanically multiplied pressure across the two master cylinders.
    The differential size of the Master Cylinder Piston Area and the Calliper Piston Area is the second multiplier take the area of the 0.625 master cylinder (0.307) and the area of say a Cosworth 2wd Front Calliper (3.87) the ratio is 12.6:1 so now for every 1 lb of force we exerted on the pedal we have 63 lb of force being exerted on each brake disk (1 x 5(mechanical) x 12.6(hydraulic)). Out of interest the pressure applied to the brake disk in the same scenario using a 0.75 piston (Area = 0.44) is 44 lb that’s only 70% of the braking force !!!!!!!

    You can also see the amazing forces involved too forget the bias bar for a second and say that 20 lb of the pressure you apply gets to the front master cylinder and you have 1270 lb at the disk / drums.

    One other issue you may find is even after all the bias settings your still getting too much rear brake then there is a simple answer, fit an inline proportioning valve and adjust as required.

    Pad Area has no measureable effect on the Pressure applied to the disk, however the pad area is important; the friction material works best between certain temperatures, too hot or too cold and they won’t perform, the smaller the pad area the hotter it will get the larger the cooler so it’s all a compromise.

    Back to assembly, before bolting everything up we need to modify the front cylinder, simply chop 8mm off the end of the rod otherwise with the bias would all the way forward the rod will hit the bias bar and bind up. Your ready to assemble now grease up the balance bar and screw on the clevis pins these need to be the same distance apart on the bias bar as the distance between the centre of the two cylinders, think about it as this is quite important. Fit the cylinders remember the front one goes nearest the centre of the pedal top!

    Most Common cylinders have -4 (dash 4) Fittings for the input and -3 for the outlet. Make sure there are no uphill sections in the inlet hoses where air can hide.


    *Note: the area of callipers can be calculates as follows:
    Single Piston on a slider (Std Sierra front and rear) = Area of One Piston
    Twin Opposed Pistons (M16 Escort Std Fitment) = Area of One Piston
    4 Pots (most aftermarket and Cosworth 2wd) = Area of 2 Pistons
    (Cosworth 2wd Pistons = 40mm Front and Rear)
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    Re: Assemble a Bias Peadal Box

    Right now i'm really confused
    So your saying that you can get more pressure out of a m/c than you put in?
    Gary didnt your post on osf say you didnt???????

    Someone please lay this to rest

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    Re: Assemble a Bias Peadal Box

    Quote Originally Posted by mk1matt View Post
    So your saying that you can get more pressure out of a m/c than you put in?
    No you cant get more pressure out of A m/c than you put in unless you connect it to another piston with a larger area (i.e. calliper) then yes it multiplies the force.

    I just found this article which has a nice interactive illustration :

    http://science.howstuffworks.com/hydraulic1.htm
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    Re: Assemble a Bias Pedal Box

    The main problem with M/Cyl calcs is people do the calcs to suit thier answers .. ie " i want more power"
    so we get this

    100lb applied to a cylinder with 1" square area gives 100psi

    100lb applied to a cylinder with 0.5 square inch gives 200psi

    so they get the higher pressure for the smaller cylinder.. do we?

    In reality the cylinder is just a fluid mover, and the different sizes are to change, or balance the pedal stroke .

    the cylinder has a force applied by a rod, connected to the brake lever, this rod the transmits the force to a non compressable fluid by means of a disc inside a cylinder. This disc has a force acting on it, and thats what people work out. What they dont work out is how much force is acctually applied to the fluid ..

    above we Have a smaller cylinder creating a higher pressure .. but

    lets look at the calculation but including the force applied to the fluid.

    100 lbs on a 1" disc = 100psi .... 100psi x 1" = 100lbs .. (or equal and opposite to force appiled)

    100lbs on a 0.5 disc =200psi .... 200psi x 0.5 = 100lbs.. (again equal)

    pressure is a system is equal regardless of size of the vessel that contains it..

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    Re: Assemble a Bias Pedal Box

    Gary not sure wat that has to do with the braking system, you dont need to calculate the actual pressure in the first cylinder, the multiplication happens in the slave (or secondary) cylinder, i.e

    100 lb on a 1" disk in the primary cylinder = 100 PSI this pressure then applied to a 2" disk in a secondary cylinder = 200 lb this is basic hydraulics.

    Did you see the link above, Matt seemed to be hung up on the same issue.
    Last edited by Clint; 26-05-2008 at 09:21.
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    Re: Assemble a Bias Pedal Box

    the whole braking system is a ratio the actual pressure is irrelavent,

    its a simple matter of leverage be it hydralics or mechanical levers a ratio of 2:1 is always 2:1 whatever load is applied,

    lets face it most applications need a 0.6 master for the front and a bigger 0.75 for the rear i think this is one of the instances where going with the flow and whats normally done is better than doing too many calculations
    Last edited by Graham; 26-05-2008 at 09:37.

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    Re: Assemble a Bias Pedal Box

    Quote Originally Posted by graham bahr View Post
    the whole braking system is a ratio the actual pressure is irrelavent,

    its a simple matter of leverage be it hydralics or mechanical levers a ratio of 2:1 is always 2:1 whatever load is applied,
    Graham thats very confusing statement however I do understand where your comming from: the combined mechanical and hydraulic multiplications can be seen as a ratio.

    However getting the correct mecanical to hydraulic multiplication ratio correct is very important, in this post we dont really need to worry about the mechanical side as its all been done for us in the pedal box and tried and tested for many years.

    The hydraulic pressure is very important to understand, theres a window of pressure that will work well, get the pad material up to the correct temprature.

    I have seen this with 0.75 up front the brake pedal is very very solid and the driver thinks its brilliant but in reality a large chunk of braking power has been lost.
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    Re: Assemble a Bias Pedal Box

    Clint, in practice with disc systems (or indeed drums on rear) and Bias boxes, when people fit the small to the front and the large to the rear, they get no bias as the small cylinder dosnt flow enough fluid to the fronts before the rears have locked, The rears needing less fluid to move the 2 pistons compared with the 8 on the front.

    I agree getting lost in calculations is wrong thing to do. The correct thing is to make sure the bias bar is straight when the pedal is applied. if its skewed against the side of the tube it has no biasing effect as its locked.

    A well know Mk1 with 6pots at the front and drums rear had burnt through a set of rear linings in a week, with the owner complaining that bias boxes are crap. After being told to swap his cylinders he reported that he nearly went through the screen, his front brakes where now working.
    Heres the drawing that i did on a thread a while back, its has been used a lot recently ..


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    Re: Assemble a Bias Pedal Box

    Surely its just a trade off between braking force and pedal travel . If you double the braking force (for same pedal force) you will have to press the pedal twice as far for the same brake pad movement.

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    Re: Assemble a Bias Pedal Box

    Quote Originally Posted by Clint View Post
    Gary not sure wat that has to do with the braking system, you dont need to calculate the actual pressure in the first cylinder, the multiplication happens in the slave (or secondary) cylinder,
    Thats sorta what i'm saying ... people do the calcs for only one side .. ie the pedal force and the cylinder size .. and this gives them a higher pressure for the smaller cylinder.
    So everyone fits the smaller cylinder to the front, and the bias is skewed so it locks .. they then fit a reducing valve in the rear, etc etc .

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    Re: Assemble a Bias Pedal Box

    so the rule is still genrally .625 to the front and .7 on the rear is it not?

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    Re: Assemble a Bias Pedal Box

    Gary the information in that scan is completely flawed;
    Firstly Pad area does not have anything to do with braking power, material choice and shape does however; in fact a larger pad can reduce the braking effort quite considerably if the material is moved towards the hub or it doesn’t get hot enough to work optimally.


    Escort Cos and S2 RST Pads Same Area but the smaller looking RST pad gave 5% more braking effort measured on a brake tester both cold and hot.

    Secondly you should reduce the pressure not the fluid flow by making the rear much harder to push (larger cylinder) the balance bar will apply more pressure to the front automatically, if you have a mismatched setup like 6 pots on the front and drums on the back then use a proportioning valve just like the manufacturers do. The diagram in the scan is very misleading as it shows the pressure out of the master cylinder which has no bearing in real life, where all that matters is the hydraulic multiplication, for instance if you put a .750 inch cylinder and feed 2 Cossie 4 pots the pressure to the disk is 30% less than if we use a 0.625 master cylinder, and therefore for the same breaking effort we need to push 30% harder on the pedal; the balance bar also applies 30% more pressure to the rear automatically, to understand this imagine a plank held one end by Cosnada and the other end by 351Escort and push on it in the middle can you see who would move the most

    Also properly designed pedal box will not bind the balance bar up as your describing as there’s not enough travel on the bars thread, Gartrac or RACE for instance, My Gartrac box I have here can go min max without the actual balance bar binding.

    If you man with the 6 pots and drums at the rear had a balance bar that was binding then that was the issue he will need to use a proportioning valve though for sure, I bet you however I could out break him with some old Cossie callipers and a correctly set up braking system
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    Re: Assemble a Bias Pedal Box

    Thats the problem though Clint.. Most readers will just copy something thats done. The more technically minded will understand the terms, and the calculations. And some who have a little bit of Knowledge will go off on a completly different tangent.

    In real practical terms, you have Huge front brakes and 2wd cossie/granada rear calipers, they then fit a 0.625 to the front, and a 0.700 to the rear because the Rally Prep book says so.. fine if you have 8 pistons on the rear and 8 on the front like the Rally Cars had. But if your brake system needs more fluid to the front than the rears you need a cylinder that can move that amount of fluid.

    I've seen so many cars with bad brakes and witness marks on the bias housing.. curing this has just been a simple matter of swapping the larger cylinder to the front, and the small on the rear.
    The diagram was written for the masses, using simple terms .. KISS theory.
    Big pads mean better brakes, so thats what everyone and their dog does, huge fronts and small rears
    As for the Gartrac box, yes its the best, but 90% of the people out there use an RD one .

    The bias bar has to lock out against its housing to provide braking on one circuit if the other fails



    Ps.. i know you can stop a car .. i was in Monza when you came across that roundabout remember

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    Re: Assemble a Bias Pedal Box

    Oh yeah I remember the Harlow run, perfect braking control as I remember

    Gary the diagram above is wrong as 4 pot pistons are opposed so they cancel each other out, it takes only half the fluid to close the gap so you only calculate for 4 pistons not 8.

    Also your still talking about fluid quantity and not pressure, its all about pressure and not fluid quantity; I could have the proportioning valve nearly off to the rear same size piston on the M/C but substancially less fluid flow as the balance bar would bias the front much more.
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    Re: Assemble a Bias Peadal Box

    Quote Originally Posted by mk1matt View Post
    Right now i'm really confused
    So your saying that you can get more pressure out of a m/c than you put in?
    Gary didnt your post on osf say you didnt???????

    Someone please lay this to rest
    if you read all that post you will see that i did

    the basic hydraulic law is pressure = force/area so area does matter, i also thought that gary had accepted that

    however in practice in an escort braking system i understand garys slant on shifting fluid, its not technicaly correct but its a simplified view from a practical stand point, since with limited pedal movement to play with (and limited cyl size choice ) you cant really choose a cylinder for optimum "power ratio" you need to choose one that makes the pedal movement acceptable to both the leg and the bias box available "twist" before lockup occurs.

    hope that makes some sense
    Last edited by Dave; 26-05-2008 at 14:03.

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    Re: Assemble a Bias Pedal Box

    Hey look at this explains it very well:

    http://auto.howstuffworks.com/master-brake2.htm
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    Re: Assemble a Bias Pedal Box

    Quote Originally Posted by Retromotorsport View Post
    Heres the drawing that i did on a thread a while back, its has been used a lot recently ..

    the problem is that its flawed, your 500 force out of each cylinder is wrong, it should be pressure and the smaller cylinder will be higher

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    Re: Assemble a Bias Pedal Box

    Clint.. again your going complicated .. the average man in the street will see 8 pistons .. he still wont calculate it, he'll just follow the rally prep book with his huge fluid requirement on the front and the tiny amount on the back.. and stick teh small cylinder on the front.

    Thats what i'm getting at, we have to keep it simple.

    The numbers dont matter.. they could be anything ..

    calipers at the front need 4 x's of fluid
    the rears need 2 x's of fluid

    so fit the cylinder that has the largest fluid movement to the calipers that require the most fluid ..

    Do Not copy anyone else unless you have exactly the same system as them ..

    And fitting a rear reducing valve in the rear line is masking a problem .. the works cars didnt have, and the cars i spec the brakes on dont have them.. they use the bias bar to adjust the brakes for hot or wet conditions.

    Mike, you never did get the equal and opposite, i just gave up on the other thread

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    Re: Assemble a Bias Pedal Box

    Quote Originally Posted by Clint View Post
    before bolting everything up we need to modify the front cylinder, simply chop 8mm off the end of the rod otherwise with the bias wound all the way forward the rod will hit the bias bar and bind up.
    This is something I have never heard before. Could the witness marks Gary talks about be due to this not being done?

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    Re: Assemble a Bias Pedal Box

    Quote Originally Posted by Retromotorsport View Post
    Clint.. again your going complicated .. the average man in the street will see 8 pistons .. he still wont calculate it, he'll just follow the rally prep book with his huge fluid requirement on the front and the tiny amount on the back.. and stick teh small cylinder on the front.

    Thats what i'm getting at, we have to keep it simple.
    I dont mind keeping it simple but lets not swap simple for wrong!

    The numbers dont matter.. they could be anything ..

    calipers at the front need 4 x's of fluid
    the rears need 2 x's of fluid

    so fit the cylinder that has the largest fluid movement to the calipers that require the most fluid ..
    This is wrong, Ill state again its nothing to do with the amount of fluid its all about the pressure.

    If you still dont understand think about this: If two lines are at different pressures then more fluid will flow in the one with higher pressure, so get the pressure right and you will have the correct amount of fluid to actuate each of the secondary cylinders (calliper or wheel cylinder)

    And fitting a rear reducing valve in the rear line is masking a problem .. the works cars didnt have, and the cars i spec the brakes on dont have them.. they use the bias bar to adjust the brakes for hot or wet conditions.
    Its not masking a problem its exactly how most modern systems are designed, nearly ALL modern cars have this setup, as a note Cosworths simply used a jet in the distribution block to feed the rear lines with less pressure.

    I never used a valve in mine, I found with the bias set about 80% forward on the bar it was near perfect as you will find with most works cars.
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    Re: Assemble a Bias Pedal Box

    if it takes the front cylinder 2 inches of travel to lock the front brakes and only 1/2 inch of travel for the rear cylinder to lock the rears .. what do you do ?

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    Re: Assemble a Bias Pedal Box

    I would worry because a Master Cylinder has only 1.25 inch of travel and the Gartrac balance bar I have here has 1.20 inch of adjustment (gartac designed this box well) so one of the cylinders can be fully compressed with the other one is hardly moving.
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    Re: Assemble a Bias Pedal Box

    Am i the only one propper confussed now,because you are both saying things that make sense but surely only one of you is right

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    Re: Assemble a Bias Pedal Box

    Attached is another setup guide I found pretty much saying exactly what i said in the first post although maybe a little simpler.
    Attached Files Attached Files
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    Re: Assemble a Bias Pedal Box

    an important point i just picked up from that link.
    the cylinder rods lenghths are adjusted in the static position to provide an initial bias for the front, this gives the smaller cyl a head start moving the req fluid and will provide a larger "working/operating window" in the choice of cylinder before the bias bar locks up at full skew.

    and gary, it was never about the = and opposite, it was about the pressure being different from different size cylinder. nice try tho

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    Re: Assemble a Bias Pedal Box

    Quote Originally Posted by Clint View Post
    I would worry because a Master Cylinder has only 1.25 inch of travel and the Gartrac balance bar I have here has 1.20 inch of adjustment (gartac designed this box well) so one of the cylinders can be fully compressed with the other one is hardly moving.
    then if your front calipers were large enough that a 0.625 cyl would not supply enough fluid in 1.25" of travel then you would need a larger cyl to the front ?

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    Re: Assemble a Bias Pedal Box

    one more observation

    with a near perfect gartrack pedal box you can utilise 1.2" of travel at the cylinder without lockout ? which gives a lovely brake power / balance.
    now the issue i see there is that with a 5:1 pedal ratio thats a 6" pedal movement ?
    dont fancy that on a twisty downhill white
    or did i miss something?

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    Re: Assemble a Bias Pedal Box

    Quote Originally Posted by alladdin View Post
    then if your front calipers were large enough that a 0.625 cyl would not supply enough fluid in 1.25" of travel then you would need a larger cyl to the front ?

    I have no idea what point you are making, a 0.625 is fine for Montes that use 44mm pistons thats about as big as you will get.
    You dont need to move 1.25" of fluid every time; with calipers you probably need to shift less than 0.2mm at the disk as the pads dont retract; unlike wheel cylinders wherethe first couple of mm of fluid with drums is simply taking up the retraction of shoes from the springs.

    now the issue i see there is that with a 5:1 pedal ratio thats a 6" pedal movement
    So you can see how little the master cylinders are actually moving under normal conditions.
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    Re: Assemble a Bias Pedal Box

    Quote Originally Posted by Clint View Post
    I have no idea what point you are making, a 0.625 is fine for Montes that use 44mm pistons thats about as big as you will get.
    You dont need to move 1.25" of fluid every time; with calipers you probably need to shift less than 0.2mm at the disk as the pads dont retract; unlike wheel cylinders wherethe first couple of mm of fluid with drums is simply taking up the retraction of shoes from the springs
    So you can see how little the master cylinders are actually moving under normal conditions.
    i wasnt making any point, other than trying to help those im sure are struggling to follow.

    Quote Originally Posted by Clint View Post
    I would worry because a Master Cylinder has only 1.25 inch of travel and the Gartrac balance bar I have here has 1.20 inch of adjustment (gartac designed this box well) so one of the cylinders can be fully compressed with the other one is hardly moving.
    my second post was intended to show that while you might indeed have 1.2" of adjustment with a good pedal box, in practice it would leave an unacceptable pedal travel.

    i dont have any experiance of swapping m/cyl myself so have relied on information i have read.we seem to have a difference in supplied info ?
    whilst your saying that the cyl size has little affect on travel due to the small amount of fluid moved ( correct me if im wrong in saying that)
    others have said that the difference in travel cannot be dialed out via the bias bar skew/adjustment available.

    do you put this down to an incorrect bias box setup?

    please dont take my questions in the wrong way, i find this interesting due to
    a, the general lack of understanding on the subject and
    b, my own lack of practical experiance in the matter.

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    Way too much free time Decade Plus User Retromotorsport's Avatar
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    Re: Assemble a Bias Pedal Box

    Quote Originally Posted by Clint View Post
    I would worry because a Master Cylinder has only 1.25 inch of travel and the Gartrac balance bar I have here has 1.20 inch of adjustment (gartac designed this box well) so one of the cylinders can be fully compressed with the other one is hardly moving.
    Thats just what i wanted you to say ...

    so with the bias bar fully wound over you can have one M/Cyl all the way in and the other hardly moving ... but you now have no biasing left ... fit a larger cylinder on the long side and you get... a bias bar still set in the middle, so on hot sticky days you can give some more to the fronts and on wet days, more to the rear .

    In Practice using a variety of pedal boxes, i have found that using large 4 pots up the front with a 0.7 - 0.750 M/Cyl and the Granada/Sierra Calipers on the rear with a 6.25 -6.50 M/cyl has left the bar in the middle of its adjustment and being straight in its housing when brakes are applied.
    The bias allready given a front advantage by having the center of the bias offset to one side by the manufacturer.

    That is probably the most common set up used now adays on street cars

    Rally cars using AP's all ound on a FF atlas with a Gartrac pedal box should use the 0.625 front and 0.700 rear.

    Just out of interest Clint ... has the Gartrac box got a built in bias ? like this.

    Last edited by Retromotorsport; 27-05-2008 at 08:44.

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    Re: Assemble a Bias Pedal Box

    Gary, to equalise the balance bar you shorten or lenghen the rods, you dont need to put the cylinders on the wrong way around

    Explained better in the PDF that attached up a couple of posts.

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    Re: Assemble a Bias Pedal Box

    I know you can shorten the rods ... but, if things fit as standard then replacements can be bought begged or borrowed.
    As has been shown .. theres many ways to skin a cat .. and the point i'm trying to get across is whats right for one set up may not be right for another.
    The vast majority of posts about bias boxes, and i must say they are normally on another forum where parts and cars are to a budget, the posts allsay my brakes are crap.. the replies they get are ..
    what way round are your M/cyl's
    you need the small on the front
    thats what i have
    you need to buy a reducing valve
    i'm going back to standard brakes
    why a bias box works mine does .. i used a reducing valve and it works
    etc
    etc

    when swapping the large to the front works in 90% of cases.

    I had a look at someone brakes a while back .. to get the clevis equi distance from the M/cylinders would have required an inch or so being removed ..
    The bias bar as soon as you pushed a pedal just locked out in the tube giving next to nothing on the fronts .. yes a cutting down of the M/Cyl pushrod would have equaled it up a bit, but i dont like modifying parts to fit. A swap of the cylinder outlets and we had a bias bar that worked and brakes that worked .. simple fix.
    As I said on the first drawing.. i wish i had a £100 for every time i had seen a tube with witness marks on it from the bar locking out on it.
    Of course this all go outs the window when an axle shaft is slightly bent .. the pad knock off on the rear can be huge .. see different set up required there, yes a new shaft would be best, but sometimes you just get " its my brakes that are crap not my shafts"

    And the worse case senario is they go out and try them.. feels sorta ok.. then into a bend the traffic has stopped.. stamp on the brakes and too much rear brake, oppps.

    I think we both agree, that the first job once the brakes are bled is to look up at the bias tube, and make sure the bar is straightish .. if not, A or B .. cut down or swap cylinders.

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    Re: Assemble a Bias Pedal Box

    The idea of this post was to try and explain the correct way to set a bias box up, what your describing is a quick fix for a poorly set up bias box.

    I will spend some time updating the original thread to make it easier to understand and also add some pictures.

    I will also explain what to look for in a box so people can see if thay have one with correct geometry etc.

    Swapping the cylinders is the wrong way, you dont want lots of pressure to the rear and as I have shown moving from a 0.625 M/C on the Front to a 0.75 can reduce the braking effort by 30% even though the pedal will feel harder giving a false sense of power.

    Even if you cut the rod you can still borrow one from track side as the rods are removable.
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    Re: Assemble a Bias Pedal Box

    Thats another thing that i just cant get my head around .. the difference between the pressures ...

    simplyfiying things

    2 cylinders .. one 1 square inch area and one 0.5 square inch in area ..

    100 lb applied to both

    the 1" one has 100 PSI

    the half inch one has 200PSI

    force dived by area, yes?

    so the smaller master cylinder provides more pressure ... but does it ..

    the cylinders disc (the thing that transmits the applied force) then passes the mechanical load from the pushrod to a non compressable fluid (ok it does a bit but we will forget that)

    now the 1" m/cylinder has 100psi acting on a 1inch square area .. =100psi
    the 0.5" m/cylinder has 200psi acting on 0.5 of an inch .. =100psi

    see the force applied by the pedal goes into the formula .. and we get the pressure on one side of the disc .. (100psi and 200psi) but no one then calculates the force applied to the fluid ..
    theres a 100psi applied to the fluid over a square inch.. =100psi
    theres 200psi applied to the fluid over 1/2 a square inch =100psi

    2 drawings ..


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    Re: Assemble a Bias Pedal Box

    My favourite quote this month/year.
    "Gary, I love you very much, but you are not always right"
    Helen (Mrs Retro)


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    Re: Assemble a Bias Pedal Box

    Dave she normally says ... when I married Mr Right I didnt know his first name was Always .

    This post is great though, as we have people thinking about this, and not just copying others, wether they are right or wrong.

    I'm still learning, and i have my way of doing bias boxes, i've tried the shorten the rods route, and i still wasnt happy with the bias bars angle ..
    and i still cant get Newtons Law of for every force there is an equal and opposite force.

    so put 100 in get a 100 out .. until you have some form mechanical multiplier.
    And a master cylinder just moves fluid.

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    Re: Assemble a Bias Pedal Box

    guess my pedal box will be coming back out then....
    never realised it would be so complicated!

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    Re: Assemble a Bias Pedal Box

    Mark.. is yours bled up.. if yes and you push the pedal and the bias bar stays pretty straight when set in the middle of its adjustment then leave it alone ..

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    Re: Assemble a Bias Pedal Box

    Quote Originally Posted by Clint View Post
    Gary the diagram above is wrong as 4 pot pistons are opposed so they cancel each other out, it takes only half the fluid to close the gap so you only calculate for 4 pistons not 8.
    this doesnt sound correct ?
    since the gap is between the pad and disc, assuming both are backed off evenly then all 8 pistons move the "full" distance ie from any pad to disc distance.

    on the other hand taking a 1 pot sliding caliper then its classed as a 2 pot since the one piston must in effect close both gaps and move twice as far fluid wise.

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    Re: Assemble a Bias Pedal Box

    Quote Originally Posted by Retromotorsport View Post
    Mark.. is yours bled up.. if yes and you push the pedal and the bias bar stays pretty straight when set in the middle of its adjustment then leave it alone ..

    not yet.. need to get some alloy hubs and my front legs back before i can fit the fronts..

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