Fw: Rear Proportioning valve mods
benswann at comcast.net
Tue Nov 15 11:19:28 EST 2005
As forwarded from Mark Woodland..he is not able to get responses at his work
due to filtering of automated responses.
Please include Mark MWoodland at Dentsply.com in your anticipated helpful
My take - Mark you might want to remove the Proportioning valve and clean -
purge/blead fluid out to valve, re-install cleaned valve and continue fluid
purge out rears - as in doing normal brake bleed sequence. Right Rear, Left
Rear, Right Front, Left Front. you'll probably have to open up the lines to
clean and may even need to replace the calipers if it has been sitting long
as they tend to lockup internally. My guess is the fluid may have absorbed
some water in it and over time has caused some corrosion and also turned to
schmutz (technical term for congealed grody fluid). Get all that old fluid
out of the system.
[----- Original Message -----
From: <MWoodland at Dentsply.com>
To: <benswann at comcast.net>
Sent: Tuesday, November 15, 2005 9:33 AM
Subject: Rear Proportioning valve mods
I'm close to getting Gina ('86 5KTQA) back on the road, and am struggling
with the rear brakes.
A few years ago, I replaced the rear brake proportioning valve on my wagon
with a "better" one, and then let it sit for the last 3 years. When I pulled
the rear caliper to replace a hose, only a few drops of brake fluid came
out, and it seems that flow is blocked at the proportioning valve. The state
of the rear rotors also leads me to believe that only the bare minimum of
pressure was being exerted by the calipers.
Has anyone ever rebuilt, modified or otherwise defeated the proportioning
valve, i.e. gutted it or locked it at 'full-flow'?
I found the old one, and dismantled it last night, and after cleaning it
out, can make it flow from very little, to slightly more. I'm thinking about
opening it up a bit with the Dremel, as there is a built-in bias, front to
rear, due to the piston sizes, numbers, and pad sizes, figuring that any
propensity to lock will be handled by the ABS system.
Any thoughts? Experience? Tales of horror?
Please respond to mwoodland at dentsply.com
Thanks in advance.
Global IT Compliance Project Leader
Dentsply International, Inc. NASDAQ (XRAY)
570 W. College Ave.
York, PA 17405
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