Fw: Rear Proportioning valve mods

Ben Swann 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.

 Mark Woodland
Global IT Compliance Project Leader
Dentsply International, Inc.  NASDAQ (XRAY)
570 W. College Ave.
York, PA 17405
Phone: 717-699-4187
Fax: 717-849-4764] 

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