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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > Technical question about abs bleeding and closed systems



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      02-17-2013, 09:08 AM   #1
ashmostro
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Technical question about abs bleeding and closed systems

I was thinking about this recently when I bled my abs module using the poor man's method (no INPA here). My question is, if you necessarily need a method to "open" the abs module in order to bleed out trapped air, why then would trapped air in the module even contribute to a soft pedal under normal use? Succinctly, if the fluid and any air in the module is hermetically isolated from the rest of the system until activated, shouldn't a system's pedal feel not be influenced at all by the module under normal braking?
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      02-17-2013, 02:27 PM   #2
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Quote:
Originally Posted by ashmostro View Post
I was thinking about this recently when I bled my abs module using the poor man's method (no INPA here). My question is, if you necessarily need a method to "open" the abs module in order to bleed out trapped air, why then would trapped air in the module even contribute to a soft pedal under normal use? Succinctly, if the fluid and any air in the module is hermetically isolated from the rest of the system until activated, shouldn't a system's pedal feel not be influenced at all by the module under normal braking?
How did you introduce air into your ABS unit? The only way to bleed the ABS unit properly is using activation of the motors and pumps. The poor man's method can only bleed air out of the lines, hoses and calipers.
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      02-17-2013, 03:19 PM   #3
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Slippery road, brake hard, engage abs. Return to base, bleed. Big bubbles come out about forty seconds into the bleed (freshly bleed before already).

Not a glamorous as using INPA, but it worked.
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      02-19-2013, 06:14 AM   #4
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No answers to the core question at hand here though? Anyone want to opine?

cheers!
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      02-22-2013, 01:54 PM   #5
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Oh well, guess not. Darn.
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