Anyone changed the brake pedal ratio?

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James Wieler
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Anyone changed the brake pedal ratio?

Post by James Wieler »

Has anyone tried moving the booster plunger closer to the pivot point? This should increase the pedal ratio. Can the booster plunger be swapped out with a threaded rod so I can put a rod end on it?
thanks
James
Cossy sway bar, Powerflex, Dynalites, Focus SVT rotors,Koni yellow sleeve over 8"x300lb/in springs,Scorch bumper cover, 17x7.5x40mm Binno wheels, 225/45-17 Kumho 712 tires
hEaT
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Re: Anyone changed the brake pedal ratio?

Post by hEaT »

James Wieler wrote:Has anyone tried moving the booster plunger closer to the pivot point? This should increase the pedal ratio. Can the booster plunger be swapped out with a threaded rod so I can put a rod end on it?
thanks
James
Should be able to. The one in my later style booster falls out easily. I'm sure you could thread what's there, put a coupling on, and make it longer.
timxr8
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Re: Anyone changed the brake pedal ratio?

Post by timxr8 »

What issue are you trying to fix with changing the brake ratio?
Tim Spencer
1988 XR4Ti Duratec project car
2011 Taurus SHO daily driver...not stock.
James Wieler
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Re: Anyone changed the brake pedal ratio?

Post by James Wieler »

more force applied to the master with the same pedal effort. I'm looking at various calculators that use pedal ratio, master cal piston diameter, caliper piston area with a goal of 1000-1200 psi line pressure.

I think I'll start by ordering a Wilwood brake pressure gauge and see where I'm at. I just wanted to test the waters and see if this was something someone had tried.

I'll have to crawl under the dash and remind myself what the pedal/master attachment area looks like.
thanks
JAmes
Cossy sway bar, Powerflex, Dynalites, Focus SVT rotors,Koni yellow sleeve over 8"x300lb/in springs,Scorch bumper cover, 17x7.5x40mm Binno wheels, 225/45-17 Kumho 712 tires
John V
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Re: Anyone changed the brake pedal ratio?

Post by John V »

James Wieler wrote:more force applied to the master with the same pedal effort. I'm looking at various calculators that use pedal ratio, master cal piston diameter, caliper piston area with a goal of 1000-1200 psi line pressure.

I think I'll start by ordering a Wilwood brake pressure gauge and see where I'm at. I just wanted to test the waters and see if this was something someone had tried.

I'll have to crawl under the dash and remind myself what the pedal/master attachment area looks like.
thanks
JAmes
Ya know James, seems like a lot easier and probably better way than these onliine calculators that guys use for fingering out brakes and spring rates and answers to easy things might to be to look at what the normal things done in previous practice is..what I call "praxis"
Well I call it that and a few other guys too who were way smrater-er than me:
Origins

In Ancient Greek the word praxis (πρᾶξις) referred to activity engaged in by free men. Aristotle held that there were three basic activities of man: theoria, poiesis and praxis. There corresponded to these kinds of activity three types of knowledge: theoretical, to which the end goal was truth; poietical, to which the end goal was production; and practical, to which the end goal was action. Aristotle further divided practical knowledge into ethics, economics and politics. He also distinguished between eupraxia (εὐπραξία, "good praxis")[2] and dyspraxia (δυσπραξία, "bad praxis, misfortune").[3]

Or simply put "that done in practice"...

First you establish what is used that works well (pedal ratio above 6:10 and then check what you have (barely 4.2:1) and see what you can do to go towards the known good.....

Further, practice shows us that there is a relational value between master sizing and caliper piston sizing that give a good hydraulic balance and a "good pedal" and good modulation at the point of lock up, and THEN separate from that is the amount of LEG you have to do to make the car slow down..
Viewed as 2 distinct things, that is by approaching each objective in detail, you can usually do better..

It seems you are retaining a booster?
I don't know because as I said in that PM, you seem to have ideas in mind and your questions seem to be questions looking for a confirmation...and so you drib and drab information making a rational answer a virtual impossibility. I have no idea what your ultimate goal is.

The way I approached this same question was the same method I used many years ago when I was not progressing along the career path I had chosen and had plateaued out...I broke down 1 lap into all the distinct motions and made everything into short easy segments:
Starting. (start gate operation, start on dirt, or start on concrete)
Full throttle acceleration thru the gears by 100% butt dyno (no sound--cause no sound is there on real starts with 32-35 others)
braking
End of braking and corner initiation
Full thottle axx.

I'd make the pieces simple and discreet elements and then think about them.
Then string them together..

2 years later i was paying the rent, buying trucks and airline tickets and saving about70% of what i made.

Here we all know just what for did. Sizes, diameters, thicknesses, master sizes, even pedal ratio..
That seems to be a better starting place than some random generalised on-line calculator thing.

But, as always wot da fuq do I know.
John Vanlandingham
Sleezattle WA USA
CALL =-> (206) 431-9696 <-= CALL

http://www.rallyrace.net/jvab/
James Wieler
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Re: Anyone changed the brake pedal ratio?

Post by James Wieler »

I don't have the books, can you share those dimensions with us John?
Master bore size?
Pedal ratio?
thanks
James
Cossy sway bar, Powerflex, Dynalites, Focus SVT rotors,Koni yellow sleeve over 8"x300lb/in springs,Scorch bumper cover, 17x7.5x40mm Binno wheels, 225/45-17 Kumho 712 tires
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