| [GMCnet] REAR BRAKE TORQUE REACTION ARM SYSTEM [message #86345] |
Thu, 27 May 2010 20:18  |
Charles Aulgur
Messages: 78
Registered: March 2006
Karma:
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There have been some discussion as to what is available for a parking
brake when installing the rear brake torque reaction arm system. Rick
Flanagan and Jim K have the hydraulic line lock on there GMCs which
they are very happy with. You don't need to apply full brake
pressure for a parking brake and if you have a good brake system you
do not have to worry about leak-down. This is a much more reliable
system then having some additional air cylinder pulling on the brake
pedal which is also requiring your MC to stay under pressure which is
the most likely place for a hydraulic brake fluid leak. On most any
GMC, the MS will leak down if you push on your brake pedal as hard as
you can with the engine running. Just try it some time and most
likely your brake pedal will slowly move downward but it is so slow
that it does not affect your braking ability when driving. This is
something I have never been able to solve so I quite wasting money on
new MS. And yes; I do know how to properly bleed the MS and brake
system.
When Jim K. sent me the production version of the brake torque
reaction arm system to install on my GMC he also sent the 70 mm
Elderado calipers for the rear two wheels and asked me to invent some
type of actuator that would supply enough force to hold the GMC on an
incline of at least 15 degrees slope. What I have done is install a
HF 12vdc scissors jack on the floor on the left side of the driver
seat and connected it to the OEM parking brake cable which actuates
my much modified cable system which applies a balanced force to each
rear wheel caliper, which you cannot do on with the OEM cable
system. The jack will develop up to 4000# force so it has sufficient
force capability. I can hold my GMC on an 8% grade but I have been
having problems with cable fittings holding enough force. So far I
have broken the cables four times. When I get back to work on it I
will replace all the old OEM cable with higher strength cables.
I am doing all this testing for Jim K as I have a parking brake on
one side of my coach that I showed a lot of people at Auburn. It is
attached to the outer frame of the quad air bag support frame and has
a scissors jack action that forces brake pads out against the the two
rear wheels and locks the wheels together with enough force that
will hold the coach in the "braked" position if I let all the air out
of my air bags. Photos and descriptions have been on the GMC photo
site for over a year and I have had no interest shown. The funny
looking "U" shaped thing that was setting next to my GMC at Auburn
was a working model operated by the 12 vdc motor, gears and threaded
rod from another HF scissors jack. It is for sale for $200 if anyone
wants it but it only fits on the quad bag support frame. I made it
for Jim but he didn't think there would be enough interest to make
production worthwhile.
Chuck Aulgur
La Mesa, CA
76 Royale with full six wheel brakes
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