Date: Thu, 24 Mar 2005 20:02:53 -0500 From: "doug" <dougejNOSPAMnospamFREEhotmail.com> Subject: Re: 9-3 brake rotor
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 "Mike" <mteeplesnospam.net> wrote in message news:dpj6415dl9pqvh9iavp1dr2vma6gvdqjvjnospamcom... > > If brake fuild in the system wasn't meant to go bi-directional, where > does the brake fluid go after we release the brakes? Thru the lines > over to the other side? :) > > A guide is a reference tool and logic is another good tool to use when > DYI. > > \ Mike T. / > > > On Thu, 24 Mar 2005 18:16:45 -0500, "doug" > <dougejNOSPAMnospamFREEhotmail.com> wrote: > >>Dave >> >>What I posted says it all - if one forces brake fluid through any ABS >>system >>in a direction it was not intended to flow, there is always the potential >>for damage. The electronically controlled solenoid valves in a hydraulic >>control unit are not designed for bi-directional flow. The act of forcing >>a >>piston back into its bore in the caliper can - and occasionally does - >>cause damage. Why even risk it if it can be avoided so easily? >> >>This isn't a Saab issue specifically; rather it's concept that applies to >>cars with ABS in general. My advice is based on many years of experience >>and >>common sense. Factory repair manuals are great for providing info on how >>to >>do repairs on proprietary components, or for wiring diagrams or >>troubleshooting diagrams. But does one need to refer to Saab documentation >>to do decide if it's better to avoid damaging an expensive component by >>following my suggestion? I think not. >> >>doug >> >> >> >> >>"Dave Hinz" <DaveHinznospamcop.net> wrote in message >>news:3agoirF68k3u0U1nospamvidual.net... >>> On Thu, 24 Mar 2005 15:53:35 -0500, doug >>> <dougejNOSPAMnospamFREEhotmail.com> wrote: >>>> >>>> Under no circumstances should you push the caliper piston back into the >>>> bore - there is definitely the potential of damage to the ABS. >>> >>> Can you show any Saab documentation that says that? >>> >> >
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