Brake BOOSTER - How necessary for street use ?

[oldcorollas]

i like stating the obvious.. because eventually people understand... i hope...

I loose M/Cyl piston travel distance doing that, but I will try that first though and then see if I still need to step down in M/Cyl size.

err.. or you gain pedal travel....

i'll make it simple.
unless you increase brake size, then you are only making a compromise between pedal travel, and pedal effort.
unless you make brakes bigger, then to reduce pedal effort you MUST increase pedal travel.
unless you make brakes bigger, then to reduce pedal travel you MUST increase pedal effort.

it is an inescapable mathematical relation

so.. unless you are going to make brakes bigger, choose the pedal effort you are prepared to live with, then change the pedal ratio and the master cylinder bore and displacement to suit the chosen pedal effort.
there is no mystery involved, it is just a calculation

[abently]

I'll find you the equations.... but to reduce the pedal Pressure, you need to move the point ,where the Piston Arm connects to the Pedal arm, closer to the pivot point thus reducing pedal travel. On same sized M/Cyl.

You can try this on a scale at home, put the scale on the floor, get a plank of wood or similar , one edge on the ground, the other on the scale, and then move a weight up and down the wood and see how it affects the readings.

[oldcorollas]

is this the same person that started the thread?

the equations are SIMPLE.... just area and leverage and force.

but i would like to see how you formulate them

but to reduce the pedal Pressure, you need to move the point ,where the Piston Arm connects to the Pedal arm, closer to the pivot point thus reducing pedal travel. On same sized M/Cyl.

PEDAL RATIO
and you are wrong anyway. moving it to the position you stated will reduce master cylinder travel, but increase pedal travel, whilst reducing pedal force.

i'm not sure why you are trying to explain the concept of leverage... it has been the subject of this thread for at least a little while

but good to see you are finally coming around

[abently]

Oooookay, yes I should have probably read your last post a bit better.

Yes, trying to reduce pedal Force whilst using standard 1" M/Cyl.

Anyhow, at the moment Max Pedal travel = Max possible M/Cyl Piston Travel.

[oldcorollas]

so.. you need to make the pedal longer, move the pivot point and the master cylinder up, and then you can decrease pedal effort, but it will only be by % as there is only so far up you can go.

[Disturbed1]

i have always wanted to do remove the brake booster myself but was under the impression u need 1 for legalities, since we are after the same end effect (no brake booster and similar brake feel to be legal still) ill be alittle more descriptive and see if any1 else can jump in and help

toyota mz20 soarer - weight about 1350kg
stock brakes = 280mm single pot front and 260mm(thats a guess) single pot rear
my upgraded brakes are 332mm ferrari f40 4-pot calipers and yet to upgrade the rears (wil be 300mm twin pots though)
its a daily driven car which is already stripped of the luxuaries (aircon,powersteering, cruise control, heater, sound deadner... - theres a reason why its lighter then stock

so whats the cheapest and safeset way of removing the break booster, is the brake upgrade substantial enuff to help combat breaking effort required?? im not fussed it i have to apply slightly/realistically more force but dont want it to feel like a brick and be dangerous at the same time. as a daily car i mingle with traffic so must be safe for all road users

i want to remove it to tidy engine bay (as pathetic as that may sound to some) but i want to simplfy my car as much as possible. the car will eventually see its fair share of track time

[Rodger]

Gotta love all this.

abently,

Must recall what "Cromley" keeps saying about how many kilos or Nm's the V8 boys need to push their brakes. Anyone know?

I'd have stoped debating by now and be a do'er. I'd bolt all the brake stuff together that you have now in the car and try pushing the pedal with no vacuum and then start the engine and try with vacuum assist. Then go for a drive. Again if you can test the brakes on an RTA (who ever they are in NSW) machine and they pass without booster assistance then so be it.

If you do not have any parts then start with all the OEM stuff. It is a lot of calculations (simple, but several factors) that can optimise the brake set up but then the optimum may not be physically feasable.

Now, to add to the Lancruiser experience
In my TA-22 the pedal is very firm but bites hard and quick when cold. I have a 1 inch M/C on a OEM TA-22 booster pushing Magna calipers onto RA-65 discs. I do not like my pedal feel when cold but is great when they heat up on the track.

Regards

Rodger

[oldcorollas]

toyota mz20 soarer - weight about 1350kg
stock brakes = 280mm single pot front and 260mm(thats a guess) single pot rear
my upgraded brakes are 332mm ferrari f40 4-pot calipers and yet to upgrade the rears (wil be 300mm twin pots though)

1. braking force at wheel = braking force at disc x disc diameter / wheel diameter
(here braking force is frictional force applied.. terms chosen for simplicity)

2. braking force at disc = friction of pad x force applied to pad.
3. force applied to pad = caliper piston area of one side of caliper x fluid pressure
4. fluid pressure = force on master cylinder piston from pushrod / area of master cylinder piston
5. force on master cylinder piston from pushrod = force on brake pedal x distance from pivot to pedal / distance from pivot to pushrod.


making it into unreadable form

say....
A= braking force at wheel
B= braking force at disc
C= disc diameter
D= wheel diameter
E= friction of pad
F= force applied to pad
G= caliper piston area of one side of caliper
H= fluid pressure
I=area of master cylinder piston
J=force on master cylinder piston from pushrod
K=force on brake pedal
L=distance from pivot to pedal
M=distance from pivot to pushrod

1. A = B x C /D
2. B = E x F
3. F = G x H
4. H = J / I
5. J = K x L / M

so...
A = CEGKL/IMD

.... and that is how you affect braking by the changes you make.

edit, fixed equations

[Disturbed1]

cheers for the reply but i think u just confused me that little more

need to investigate each parameter of the braking system i think

[abently]

cheers for the reply but i think u just confused me that little more

need to investigate each parameter of the braking system i think

You had the right idea by going to larger discs, but the different Calipers are going to mean you need a larger M/Cyl to offset the caliper Pistons onto the discs....

Also, its probably wise to find out how big of a Brake setup you really need as there is a point where you can be too large and find yourself locking up the tyres with very little pressure on a Booster system. To give you an example, the first car I ever owned, I setup 275mm Front discs - Twin Piston calipers, Ferodo DS2500 Pads (Factory rear drum brakes - 1100Kg vehicle) and was running 225mm wide Potenza GIII tyres. Boosted system, ridiculously easy to lock up the tyres under light rain and still too easy to lock up the tyres under mild deceleration.... Very good for practicing manual ABS though...

Anyhow the point is, what you want is just enough braking ability for your vehicles weight and tyre combination. Anymore is just a disadvantage, ie extra free-sprung weight, less real control of brakes with more pedal pressure the you need to also.

If I were in your position, I would just try to switch to some Twin-Piston Calipers for the fronts (possibly from a later or Jap model that bolt up), get some really good Pads (Competition Friction can machine Ferodo pads to almost whatever Caliper) and good wide tyres (Toyo RA1's or Bridgestones RE050). You've already cut some weight out of it and I'ld say you'll probably remove even more, so the need to upgrade to bigger discs and Calipers isn't as necessary.

Plus sticking to the Factory setup (a bit modified) means messing about with pedal ratio's and M/Cyl diameters is a bit more straight forward rather then guess work.

[oldcorollas]

braking force at wheel = (disc diameter)x(friction of pad)x(caliper piston area)x(force on brake pedal)x(distance from pivot to pedal) / (area of master cylinder piston)x(distance from pivot to pushrod)x(wheel diameter )

so.. in other words.... to increase braking.. increasing each of these will have the same % effect
-disc diameter
-friction of pad
-caliper piston area
-force on brake pedal
-distance from pivot to pedal

and decreasing these will have the same % effect (on increase in braking)
-area of master cylinder piston
-distance from pivot to pushrod
-wheel diameter

once you choose your disc size, your wheels and your calipers, your pads, and how hard you want to push the pedal.. you are left with a shorter list
increasing each of these will have the same % effect
-distance from pivot to pedal

and decreasing these will have the same % effect (on increase in braking)
-area of master cylinder piston
-distance from pivot to pushrod

with the relation that.. (~ is proportional to)

braking force ~ distance from pivot to pedal / (area of master cylinder piston
x distance from pivot to pushrod)

and that is what you play with in the cabin of car

[Disturbed1]

no way id downgrade from my brembo setup running pagid black rs4-2-1 pads atm.

i have noticed that wheels tend to lock up easier

my front break upgraded saved about 2kg total on factory setup.

ill be running 235 45 17 tyres - unsure what type (either semis or just real good street compound)

also running pbr500 brake fluid

i just want bigger rears to even up the balance alittle more.. and if i could get away without running a brake boster, and still be legal - id be all for it

[oldcorollas]

Anyhow the point is, what you want is just enough braking ability for your vehicles weight and tyre combination. Anymore is just a disadvantage, ie extra free-sprung weight, less real control of brakes with more pedal pressure the you need to also.

If I were in your position, I would just try to switch to some Twin-Piston Calipers for the fronts (possibly from a later or Jap model that bolt up), get some really good Pads (Competition Friction can machine Ferodo pads to almost whatever Caliper) and good wide tyres (Toyo RA1's or Bridgestones RE050). You've already cut some weight out of it and I'ld say you'll probably remove even more, so the need to upgrade to bigger discs and Calipers isn't as necessary.

Plus sticking to the Factory setup (a bit modified) means messing about with pedal ratio's and M/Cyl diameters is a bit more straight forward rather then guess work.

what are you talking about?
bigger brakes than you need (diameter wise) REDUCE the pedal pressure required to generate the braking force... read my above post.. slowly.. take it in and learn something.. (assuming i didn't make any mistakes )

your "advice" is not very helpful. how about explaining how twin pistons will help.. opposed or sliders and what is the difference..
how do you know those brakes are big enough? it depends on the speed he will be travelling, how many times he wants to stop, and in what time frame, so he can shoose the thermal mass required to not overheat the pads

funny how you go from not knowing how boosters or pedal ratios work and are now giving out advice again...


Disturbed, use the above formula to work out what you need to change and by how much, based on your current booster and leg effort required. it is very easy to predict how much force and how much pedla travel will result, assuming you can measure the things required (most are constant, so don't need to be measured for a "relative" comparison)

[Disturbed1]

are these kinda pedal boxes illegal for street use

[The Real Roadrunner]

funny how you go from not knowing how boosters or pedal ratios work and are now giving out advice again...

isn't it the same guy that strted the thread asking for advice? and the same guy that doesn't even understand how a caliper compensates for rotor/pad wear? total fucktard

disturbed1, it depends on what adrs your car has to comply to and also whether an engineer will sign off on it, but yes they work well (just filling those resivouirs would be a bitch) get the remote res versions.

cheers
linden