# Booster delete



## ps2375 (Aug 13, 2003)

So, here's what we've got and what we plan:
An 80' Scirocco w/ vented 9.4's in front and 200mm drums out back w/ braided lines fr & rr. The car is for Auto-X and hillclimbs and we run Diamond Racing wheels, 13" dia and have a couple sets, 8" and 9" wide. We've decided not to go bigger in front due to weight(rotational and sprung) and space inside wheel. We do have 16V rear discs to put on w/ the 22mm master cylinder and bias valves.
What I'd like to know is, can we delete the booster since we will be going w/ ITB's and would like to not have to add a vacuum reservoir and the vacuum log to feed it. Do we need a diff master cylinder for this or will it be sufficient to give us enough brake force to not have to apply serious leg to slow and stop the car under "race" conditions. I do know the force needed will go up, but will it be excessive?


_Modified by ps2375 at 12:23 PM 8-23-2009_


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## ps2375 (Aug 13, 2003)

*Re: Booster delete (ps2375)*

nobody?


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## GTijoejoe (Oct 6, 2001)

*Re: Booster delete (ps2375)*

I would use a smaller MC than 22mm if you are not using boost assist http://****************.com/smile/emthup.gif 
I would rec 17-19mm


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## ps2375 (Aug 13, 2003)

*Re: Booster delete (GTijoejoe)*

really, so we should stay with the current MC? From a fluid dynamics view, that doesn't make sense. Where the larger surface area of the 22mm MC will exert more force in the system than the smaller one for a given force applied and move more fluid for the same stroke. I don't remember the equation or the name of that "law", but has to do with press in a closed system.(Naval Nuke School was along time ago.







)


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## ps2375 (Aug 13, 2003)

*Re: Booster delete (ps2375)*

I have thought of a possible solution, Use a Vacuum booster pump from a 1.8T car(Passat) and either control it off from an MS output or manually. And poss have it plumbed to a vacuum reservoir.


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## GTijoejoe (Oct 6, 2001)

*Re: Booster delete (ps2375)*


_Quote, originally posted by *ps2375* »_really, so we should stay with the current MC? From a fluid dynamics view, that doesn't make sense. Where the larger surface area of the 22mm MC will exert more force in the system than the smaller one for a given force applied and move more fluid for the same stroke. I don't remember the equation or the name of that "law", but has to do with press in a closed system.(Naval Nuke School was along time ago.







)

Actually the fluid dynamics makes perfect sense your just slightly confused.
X force over large area makes smaller pressure.... X force over small area makes large pressure.... lbs/in^2 
500lbs/1in^2= 500psi
500lbs/0.5in^2= 1000psi
This is why decreasing the MC will increase pressure, the actual fluid flow of course will decrease, resulting in a longer stroke.....
Here is a good example, my EVO with the bremebo's has a 17mm MC, my 98 GTI (stock system) has a 22mm MC....which do you think is actually the bigger brake system (caliper sizing)???
Or you can use a vacuum pump, lots of DI motors actually use these too because of low vacuum levels at high alt.


_Modified by GTijoejoe at 9:03 PM 8-26-2009_


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## jordacheha (Mar 9, 2008)

drving without a booster is definetly doable...ive been driving my 2001 golf unassisted for several years and much prefer it. id strongly suggest tho, if you dont want the assist, to remove the booster and fabricate a adapter as i did because the assembly is not meant to run by simply unplugging the vacuum hose and it doesnt function properly


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## greyhare (Dec 24, 2003)

The term is hydraulic amplification and Gtijoejoe is correct.

I have run my old '78 with twin DCOE's and a moderately aggressive cam for years. The vacuum tap is from the #4 runner and I have never had an issue with adequate vacuum.

Once upon a long time ago ET1/SS. RC Div FTW.


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## GTijoejoe (Oct 6, 2001)

Just another tip:

Normally the lighter the vehicle the less it will be effected. Heavier vehicles normally have much higher amplifications as you could imagine.. and the reasoning is sourced from gov. regulations and understanding pedal force has to consider all ppl....like that lil 80yr old lady.


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