Can anyone help explain brake servo hosing?

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liam012
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Post Wed Jun 07, 2006 1:55 pm

Ok so i have no abs which means a servo hose going from the cylinder into a 3 way valve/t-piece to which are connected two hoses that feed the throttle body in and out. one of these air feeding hoses has an outlet Y-piece for the intake boot. Is this needed (i presume yes) so can i feed it to or from (dont know which way the air flow is) somewhere else?
can anyone explain how the servo works - sorry i dont have a clue about them but would like to find a different way of running this y piece connection instead of using the connector into the intake boot - is it possible?
thanks
jonbuoy
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Post Wed Jun 07, 2006 8:48 pm

Not really an option mate!
They're vacum pipe's that suck the air out of the servo so you have a pedal. If you start mucking around with this you might end up with a stiff pedal and hardly any braking!

Why do you want to get rid of the idea?
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liam012
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Post Wed Jun 07, 2006 10:02 pm

i have a giant m30 intake boot! no servo though :(
the boot fits the 325i throttle body and m30 air meter just right.
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Brianmoooore
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Post Wed Jun 07, 2006 10:11 pm

What's ABS got to do with this?
Brake servo is a large flexible diaphragm with atmospheric pressure one side and a partial vacuum the other side, derived from the inlet manifold vacuum (with the throttle closed) and prevented from leaking out by a one way valve.
Later versions of the M20 use a air filter- throttle body hose without the branch and the funny Y shaped pipes etc., and just have a simple hose from the inlet manifold, through a one way valve and into the servo.
I've fitted this set up to earlier cars like yours with no problems.
Anyone know what the idea behind the earlier plumbing was anyway?