Date: Fri, 25 Mar 2005 10:20:58 +0000 From: Colin Stamp <col.dustbinnospamp.plus.com> Subject: Re: 9-3 brake rotor
On Thu, 24 Mar 2005 20:02:53 -0500, "doug" <dougejNOSPAMnospamFREEhotmail.com> wrote: >When the car is running and the ABS system is energized, the >electro-magnetic solenoids are energized and the control valves are open. >Therefore, the minute amount of pressurized fluid required to move the >caliper a few thousandths of an inch can flow. And when the brakes are >released, the return action of the caliper piston seal and retraction of the >master cylinder piston does indeed cause that same minute amount of fluid to >return to the master cylinder. But remember, the valves are OPEN. This is by >design. > >When the ABS system is not energized, the valves are closed. Why would >anyone want to risk damaging the seat of these valves by forcing brake fluid >against them? If the seat is damaged, the anti-brake function is >compromised, as a leaking seat would not permit the hydraulic pressure to >the "locked up" wheel to be sealed off and diverted. > >doug > I'm afraid your idea of how ABS works isn't correct. Even with ABS the system is *always* vented to atmosphere at the fluid reservoir with the pedal is in it's resting position. There is always a free path for fluid to return from the wheel cylinders to the reservoir without needing to "force" any valves open. Just using the brakes normally, with or without activating ABS, creates vastly more pressure in the system than pushing the wheel pistons back by hand ever can. Cheers, Colin.