| Rear Disc Brake Line [message #229396] |
Mon, 11 November 2013 22:19  |
Adrien G.
Messages: 474
Registered: May 2008
Location: Burns Flat, OK 73624
Karma: 1
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Senior Member |
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Hi All,
I need help.
I’ve seen a lot of info on rear disc brakes, master cylinders, some on combination valves. My question from anyone that’s installed disc brakes on the front bogies, and kept drums on the rear, which I’m about to do; is where did the caliper brake line hook up to? The line with the drums, or a separate line from the MC bypassing the combination valve?
The drums require about 10 lbs. residual line pressure to keep the cups from leaking, disc calipers do not need that residual which would cause disc drag, heat, pad ware, lower mpg. The residual pressure is built in the combination valve. Since the rear calipers don’t need residual pressure, I think the line for the calipers should tap into the rear brake line ahead of the combination valve.
What do you gurus say? Right track, or all wet?
Thanks for your input.
Adrien & Jenny Genesoto
75 Glenbrook (26-3) Mods LS3.70 FD / Reaction Sys / 80mm Front&Intermidiate / Hydroboost / 16" Tires / Frame Rebuild / Interior Rebuild
Yuba City,Ca. Text 530-nine-3-three-3-nine-nine-6
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| Re: Rear Disc Brake Line [message #229408 is a reply to message #229402] |
Mon, 11 November 2013 23:57  |
jim kanomata
Messages: 257
Registered: March 2007
Location: fremont,ca
Karma: 12
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Senior Member |
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Adrian,
Your right about your concern with the residual, but in order to keep things simple we connect both on the same rear line as we have experienced minimal change.
Should you feel comfortable, you can install a residual valve by the brake.
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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| Re: Rear Disc Brake Line [message #229426 is a reply to message #229396] |
Tue, 12 November 2013 07:00 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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| Adrien G. wrote on Mon, 11 November 2013 21:19 |
Hi All,
I need help.
I’ve seen a lot of info on rear disc brakes, master cylinders, some on combination valves. My question from anyone that’s installed disc brakes on the front bogies, and kept drums on the rear, which I’m about to do; is where did the caliper brake line hook up to? The line with the drums, or a separate line from the MC bypassing the combination valve?
The drums require about 10 lbs. residual line pressure to keep the cups from leaking, disc calipers do not need that residual which would cause disc drag, heat, pad ware, lower mpg. The residual pressure is built in the combination valve. Since the rear calipers don’t need residual pressure, I think the line for the calipers should tap into the rear brake line ahead of the combination valve.
What do you gurus say? Right track, or all wet?
Thanks for your input.
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I'm not aware that any of the brakes need nor want "residual" pressure.The shoes in the drum brakes retract due to the pull back springs while the disk pistons more or less stay in position as the pads are engaged. They do retract very slightly due to the shape of the piston seal. The combination valve momentarily holds back pressure from the front disks so that the rear shoes can move back out on apply mode. If you have all disks on the rear you really don't need to hold back on the fronts, but if you have drums and disks on the rear, it's still a good idea to keep the combo valve in the rear circuit.
Bob de Kruyff
78 Eleganza
Chandler, AZ
[Updated on: Tue, 12 November 2013 07:01] Report message to a moderator |
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