4Runner/GX electric brake booster w/ ABS

[rockota]

not being a smart ass...

but have you tried a slightly smaller MC diameter AND moving the MC piviot up just a skosh?

I can lock my 37's at speed, using a Geo Metro Vacuum booster... (Same issue you had, no room for a dual diagh booster or one ton MC)

The key, the the added leverage when moving the pivot up.

Seriously, I went from no brakes to stopping like a pro.. ( I did test 4 different diameter MC's.. )

you have my attention... I have not tried that... I have plenty of 7/8-1.125 masters laying around, so plenty to work with.

I’ll look into this.

EDIT: How far up did you move the pivot? And any chance you have dimensions of the Geo Booster?

 

[Elvis-n-texas]

Sure. Gimme a day.
and, locate the brake calculator spreadsheet and post up your numbets/questions here.
we can guide you through it..

Edit..

Spreadsheet here.

https://bustedknuckleoffroad.com/products/brake-design-calculator

 

[rockota]

Sure. Gimme a day.
and, locate the brake calculator spreadsheet and post up your numbets/questions here.
we can guide you through it..

Edit..

Spreadsheet here.

https://bustedknuckleoffroad.com/products/brake-design-calculator

thanks for the link! Was playing around with another spreadsheet, but not nearly as detailed.

have to do some guessing on this re: COG, total weight, rotor weight... I'll have to go do some measurements on the pedal ratio

Booster multiplication - select 1-5. not really sure to what to do here. And... frankly, how the heck does one interpret this?

 

[Elvis-n-texas]

Wait.

Let me read this again..
Stand by.

Ok.

Drop the mc diameter to one inch, and recalculate

I'm not at my workstation.. so I cant tinker with the values for you.

Btw

Did you mention you tried alternate mc diameters?
( the solution is a smaller mc, and possibly moving the pivot up a skosh..

 

[rockota]

Wait.

Let me read this again..
Stand by.

Ok.

Drop the mc diameter to one inch, and recalculate

I'm not at my workstation.. so I cant tinker with the values for you.

Btw

Did you mention you tried alternate mc diameters?
( the solution is a smaller mc, and possibly moving the pivot up a skosh..

I’ll update the pedal throw with actual measurements and then play with the MC sizes.

the front calipers are off a Ram that has a 1.125 mc stock (if I remember correctly) and are similar to JK big brake kits... but I never considered the pedal ratio.

EDIT: I've tried 7/8, 15/16, 1.0, 1.125... from various applications. One major issue is that i need to have the ports on the engine side - clearance.

 

[Provience]

thanks for the link! Was playing around with another spreadsheet, but not nearly as detailed.

have to do some guessing on this re: COG, total weight, rotor weight... I'll have to go do some measurements on the pedal ratio

Booster multiplication - select 1-5. not really sure to what to do here. And... frankly, how the heck does one interpret this?

those screenshots look needlessly complicated is that the one I made?

you interpret booster multiplication based on the vacuum/pressure differential and effective area, diameter minus center rod area, to arrive at how many pounds of force the booster is adding to the pushrod.

you already know your mechanical pedal leverage and input force, so the multiplication would be however much boost you are getting beyond that

 

[Provience]

I’ll update the pedal throw with actual measurements and then play with the MC sizes.

the front calipers are off a Ram that has a 1.125 mc stock (if I remember correctly) and are similar to JK big brake kits... but I never considered the pedal ratio.

i'm running ram brakes front and rear in my van, i absolutely hated the pedal with the same ram master cylinder. stiff as all fuck. went to a smaller diameter master (aeorstar van, pretty sure) and significant difference. stops normal now

 

[rockota]

those screenshots look needlessly complicated is that the one I made?

you interpret booster multiplication based on the vacuum/pressure differential and effective area, diameter minus center rod area, to arrive at how many pounds of force the booster is adding to the pushrod.

you already know your mechanical pedal leverage and input force, so the multiplication would be however much boost you are getting beyond that

it's from Busted Knuckle and lists BillaVista as the source for the calculations... I can't imagine YOU being that complicated.

and in red... type slower so I can keep up.

 

[rockota]

did some updating... pivot to pedal is ~12.5". Pivot to brake rod is ~3.75"... estimates w/in a few points...

The Toyota brake lever has multiple components, so at least it's also complicated.

Updated spreadsheet with 1.0" mc and the correct leverage info.

 

[Elvis-n-texas]

The key value to zero in on, is the actual pressure produced vs cell b88. Red is bad...

 

[Bebop]

Yeah. 298 is nothing. You want 1000+ in there.

 

[rockota]

The key value to zero in on, is the actual pressure produced vs cell b88. Red is bad...

that makes sense... but... I can't seem to get it "not red".

Can't change rotor or calipers (rather... won't... )....

Changing the pivot point seems to make sense, but I can't get the calculator to move in the right direction. Dropping cylinder size to 1.0 makes more red.

And to think I have a minor in mathematics....


EDIT: looks like it wants a .3" MC bore... that makes no sense to me.

 

[Elvis-n-texas]

Koff koff caliper pucks to big.. koff koff..
sniff ( stupid grin )

 

[rockota]

Koff koff caliper pucks to big.. koff koff..
sniff ( stupid grin )

you mean the pistons?

not saying you're wrong... but makes no sense to me. These are otc Ram 1500 calipers, 13" JK Rotors (drilled 6x5.5) on a hybrid toyota/f450 axle... I'm not sure I can even find smaller diameter piston calipers for the front... unless I go back to wilwood... but I had the same problems with the wilwood caliper/12" rotor combo. Front brakes are mush. Rears are mini-truck fronts on solid rotors

But... I kind of get the "bigger piston requires more volume of fluid movement for the same ft/in^2 pressure" but figured that's why a larger bore MC was required.

This shit's confusing AF...

 

[Provience]

it's from Busted Knuckle and lists BillaVista as the source for the calculations... I can't imagine YOU being that complicated.

and in red... type slower so I can keep up.

quoting myself from the brake link in the FAQ stickied above here on irate. Toyota Pickup Brake Bible - 4x4 North

Pi*R*2 = surface area of brake booster diaphram.

Diaphram area*generated PSI= output force

generated PSI from the engine, hook up a vacuum gauge and read the manifold vacuum at idle, or measure it under decel if you want to get fancy and often go WOT to close. Let's say you generated 22 inhg, subtract ambient air pressure of 14 (acts on both sides of the diaphram) and you get 8 psi of effort generated from the engine.

If you have an engine that makes very low idle vacuum, anything near 14 and especially under 18, consider a small 12v vac pump or add on an engine driven vac pump depending on what fits where the best

below example uses 7" single booster with an engine that generates 22 inhg manifold vacuum

Pi(3.14) X radius(3.5)2 = 38.46 sq/inches of diaphragm surface area X 8 psi (negative pressure becomes positive force)= 307.72 lbs of output force

it's easier to just ignore the rod area, i guess.

For folks designing their system from scratch, a very reasonable Target PSI for a regular rig would be 1,500 psi hydraulic input force TO THE CALIPER

and now, here is a link that explains things easy to understand, as written by profesionals

Booster Assist Ratio | Automotive Brake System Calculator | BRAKE POWER

Brake Booster Assist Ratio. If your brake system has no booster and no ABS, enter a "1" (one) in the "Brake booster assist ratio" field. If it has no booster but it has modern ABS acting as a booster, find out the assist ratio as if it has a booster. If your brake system has a booster, enter the assist ratio. This is not a constant number, since the force applied by the booster does not increase linearly with the force on the brake pedal. Therefore, you are interested in the assist ratio at pedal pressure for maximum deceleration.You can find this number as follows: 1) Find a small bathroom scale* or other scale that can indicate at least 75 lb (34 kg) or 100 lb (45.5 kg), to show desired pressure on the brake pedal for maximum deceleration. 2) Find a spacer (piece of wood / two-by-four) or any other object that allows you to push the brake pedal with the bottom of the (bathroom) scale, using your hands (see illustration).. 3) Take off one of the front wheels to get access to the brake caliper and replace the bleeder screw with a pressure gauge designed for this purpose (see illustration). The best affordable gauge that I could find on the internet (it includes six adapters to six common bleeder ports) is from SSBC. Google it and find prices around $50 for the entire kit. Don't forget to bleed your brake caliper after you have reinstalled the bleeder screw. 4) With the engine not running, push the pedal several times to get rid of any vacuum still in the booster. Some boosters contain enough vacuum (or pressure, in case of a Hydro Boost) to assist you with 4 or 5 strokes of the pedal, so make sure all vacuum or pressure is gone. In case of a modern ABS with integrated pressure accumulator, it can take 30 strokes of the pedal (GM, Teves and Bosch) or even 50 strokes (Bendix) before the accumulator has been totally discharged and the brake pedal becomes harder to depress. 5) Get the spacer (piece of wood) and scale in position and, while you are sitting in the driver seat, press with your hands on the scale (do not squeeze, only push!), with the amount of force needed to have the dial indicate the number that you choose for "desired force on pedal for maximum deceleration". This will be somewhere around 75 lb. More or less is all good, depending on your personal preferences. Now with the scale indicating this number of your choice, have someone read the pressure gauge you installed previously in the bleed port of one of the front brake calipers. 6) Repeat step 5 with the engine running. The assist ratio you are looking for is the gauge reading from step 6 divided by the gauge reading from step 5. For example: if step 6 produced a gauge reading of 1,100 psi, and step 5 a reading of 300 psi, your booster assist ratio is 1,100 / 300 = 3.667 (so in this case you would enter "3.667" in the "Brake booster assist ratio" field) Note: You don't need to unhook the return spring that usually is installed between the brake pedal and the firewall or brake pedal bracket. This spring slightly affects your pedal pressure, but not the booster assist ratio, so for this measurement you do not need to disconnect it. * Preferably a scale with mechanical dial, since most digital scales need to be at constant pressure for a few seconds before they display a reading, which is hard to accomplish when pushing 75 lbs with your hands.

 

[Provience]

you mean the pistons?

not saying you're wrong... but makes no sense to me. These are otc Ram 1500 calipers, 13" JK Rotors (drilled 6x5.5) on a hybrid toyota/f450 axle... I'm not sure I can even find smaller diameter piston calipers for the front... unless I go back to wilwood... but I had the same problems with the wilwood caliper/12" rotor combo. Front brakes are mush. Rears are mini-truck fronts on solid rotors

But... I kind of get the "bigger piston requires more volume of fluid movement for the same ft/in^2 pressure" but figured that's why a larger bore MC was required.

This shit's confusing AF...

Master Cylinder is FULLY dependent on Brake Pedal Lever Ratio and Boost Assist.

do NOT size master cylinder to calipers. You can move the pedal several inches, the pads only need to move several thousandths

 

[Elvis-n-texas]

Master Cylinder is FULLY dependent on Brake Pedal Lever Ratio and Boost Assist.

do NOT size master cylinder to calipers. You can move the pedal several inches, the pads only need to move several thousandths

Dont fully agree, mc and slave cylinder must interoperate.

fully agree on power boost ( vacuum, hydraulic)

swapping caliper and rotor diameter mismatches the booster and master

 

[Provience]

Dont fully agree, mc and slave cylinder must interoperate.

fully agree on power boost ( vacuum, hydraulic)

swapping caliper and rotor diameter mismatches the booster and master

alright "in general" but you would need to have a tiny master with a low pedal ratio to not be able to move the largest of calipers "enough"

he's currently using the dodge calipers with the dodge master and complaining about it, because he isn't using the dodge pedal (or booster, admittedly).


and of course, small master with large calipers could result in an excessive pedal travel complaint and whatnot.

 

[Elvis-n-texas]

... and the solution here, is moving the pivot pickup .. up..

I have zero issues with a fat pedal travel... better feedback
;)

 

[rockota]

... and the solution here, is moving the pivot pickup .. up..

I have zero issues with a fat pedal travel... better feedback
;)

I’m assuming there’s a mathematical formula for how far the pivot should be moved up?

Beyond a “skosh”... cause I don’t know what that means... is is more than a “tad” and less than a “spoon full?”

 

[Elvis-n-texas]

Try to toggle the b88 line and actual torque ( pressure ) from red.

You are on a voyage of discovery, swapping Toyota developed caliper/rotor..
( my rig, stock FJZ80 axles/rotors but no room for a stock booster. The Geo metro booster fits, but cannot provide the required brake torque.. so, dropping the Master diameter and multiplying foot torque by moving the pivot point up, resolves the issue)

You can pre design with the spreadsheet, but you will discover experimentation might be the final course of action

 

[rockota]

Try to toggle the b88 line and actual torque ( pressure ) from red.

You are on a voyage of discovery, swapping Toyota developed caliper/rotor..
( my rig, stock FJZ80 axles/rotors but no room for a stock booster. The Geo metro booster fits, but cannot provide the required brake torque.. so, dropping the Master diameter and multiplying foot torque by moving the pivot point up, resolves the issue)

You can pre design with the spreadsheet, but you will discover experimentation might be the final course of action

according to this calculator, there's the stock toyota stuff can't create enough pressure to stop a 1/10 scale RC car. The stock components only create 505 lbs of pressure. I can only get to a positive force number if the booster is making 7x the power.

confusing AF.

 

[Provience]

according to this calculator, there's the stock toyota stuff can't create enough pressure to stop a 1/10 scale RC car. The stock components only create 505 lbs of pressure. I can only get to a positive force number if the booster is making 7x the power.

confusing AF.

brake comparison chart.xlsx - Google Drive

I dunno if you can edit this or not, try it and see if it makes more sense (or not, haven't look at it in a few years)

Brake System Component Comparisons | Pirate 4x4

from post 1 in that thread

BoosterBrakePressureChart.pdf (classicperform.com)

this chart talks about booster added pressure, which is neglected in my excel spreadsheet

are you talking about 505 lbs of force to the tire or where? 505 lbs of input force to the master is a bit

 

[rockota]

brake comparison chart.xlsx - Google Drive

I dunno if you can edit this or not, try it and see if it makes more sense (or not, haven't look at it in a few years)

Brake System Component Comparisons | Pirate 4x4

from post 1 in that thread

BoosterBrakePressureChart.pdf (classicperform.com)

this chart talks about booster added pressure, which is neglected in my excel spreadsheet

are you talking about 505 lbs of force to the tire or where? 505 lbs of input force to the master is a bit

I’ll rerun with the one you posted.

in the excel I can only get “the system” generate 505 pounds of total force to the calipers (is how I read it).

 

[Elvis-n-texas]

ok
had some coffee \ laptop time today. (Doing my taxes)
rename this to .xls.

correct any mistakes i made entering your values.
what year Ram are your donor parts from?
what tire diameter?
and go to rock auto, dl the tech sheets for the calipers.. my go to for data (and my donor parts..) For my project, I purchased 5 or 6 different MC's to tinker with..

one thing to remember, you must manually copy the brake boosted value to cell b139.
BTW, carefully calculate your piviot valuie again. 3 is quite small. BUT the typical driver wants one inch of pedal travel, and literally a half pound of pressure :).. so they make the boosters huge.

 

[rockota]

ok
had some coffee \ laptop time today. (Doing my taxes)
rename this to .xls.

correct any mistakes i made entering your values.
what year Ram are your donor parts from?
what tire diameter?
and go to rock auto, dl the tech sheets for the calipers.. my go to for data (and my donor parts..) For my project, I purchased 5 or 6 different MC's to tinker with..

one thing to remember, you must manually copy the brake boosted value to cell b139.
BTW, carefully calculate your piviot valuie again. 3 is quite small. BUT the typical driver wants one inch of pedal travel, and literally a half pound of pressure :).. so they make the boosters huge.

I’ll play around with it tomorrow.

the Toyota lever is 12” pivot to center of pad. The pivot to the booster shaft is 3.5”... so I *think* my math is correct?

spent the afternoon f’ing with this. Pulled the 17/16 Ford master and installed a 15/16 Celica unit. Stock is 13/16.

also found out after hours of trying to bleed the system that my SpeedBleeders were f’d up, so I wasn’t able to actually bleed the rears.

no idea of it’s actually better - battery was dead. :rolleyes::rolleyes:

 

[Elvis-n-texas]

Smaller diameter mc will move less volume, but apply more pressure than a larger diameter.
try a 7/8 for grins... and move your pivot point up..
I moved mine to the point the relay rod was right at the point of deflection

 

[Lbhsbz]

I have about 10 of the electronic master/booster/ABS units I'll sell cheap from 2012-15 Tacoma and 2018-2020 4runners if anyone else wants to experiment with these

 

[mobil1syn]

are you not building pressure, not moving enough fluid or are you not getting enough assist?

 

[Provience]

I’ll play around with it tomorrow.

the Toyota lever is 12” pivot to center of pad. The pivot to the booster shaft is 3.5”... so I *think* my math is correct?

spent the afternoon f’ing with this. Pulled the 17/16 Ford master and installed a 15/16 Celica unit. Stock is 13/16.

also found out after hours of trying to bleed the system that my SpeedBleeders were f’d up, so I wasn’t able to actually bleed the rears.

no idea of it’s actually better - battery was dead. :rolleyes::rolleyes:

it's past tomorrow plus battery charge time how'd it go?