Disc/disc proportion valve
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Tuned
Joined: Mar 2009
Posts: 315
Likes: 8
From: Austin, TX
Disc/disc proportion valve
I’m installing a quick performance rear disc kit on my 68 f100 4x4. It already has 78 discs on the Dana 44 and a power booster from a previous owner.
Looking to add a disc/disc proportion valve as I get it’s needed. Trying to find the best bolt in replacement I don’t want to make new hard lines. Would this Wilwood work?
https://www.wilwood.com/MasterCylind...emno=260-11179
Looking to add a disc/disc proportion valve as I get it’s needed. Trying to find the best bolt in replacement I don’t want to make new hard lines. Would this Wilwood work?
https://www.wilwood.com/MasterCylind...emno=260-11179
Tuned
Joined: Jul 2019
Posts: 464
Likes: 80
From: Evansville, Indiana
The disc/drum master cylinder has a residual valve inside to keep brake fluid pressure on the drums after letting off of the brake pedal. If you don't remove the valve or purchase a disc/disc master cylinder, the rear calipers will eventually lock up.
Don't ask me how I know....
Don't ask me how I know....
Cargo Master
Joined: Sep 2007
Posts: 2,470
Likes: 535
From: Chandler, AZ
Why the rear discs? Are you trying to improve overall stopping power?
For disc/disc, I suggest a master cylinder made for that setup. Pick a modern ford vehicle that has similar brakes, then buy that MC. Like a 2000s F150. The prop valve you have posted is appropriate for either existing or disc/disc MC, as it is adjustable.
What I found is that the rear drums are more than adequate. I did hydro boost and improvement was very SIGNIFIGANT. Had to go down several sizes in rear wheel cylinders to keep rear from locking up, even with prop valve maxed out. Brakes are awesome even with 40" rubber.
For disc/disc, I suggest a master cylinder made for that setup. Pick a modern ford vehicle that has similar brakes, then buy that MC. Like a 2000s F150. The prop valve you have posted is appropriate for either existing or disc/disc MC, as it is adjustable.
What I found is that the rear drums are more than adequate. I did hydro boost and improvement was very SIGNIFIGANT. Had to go down several sizes in rear wheel cylinders to keep rear from locking up, even with prop valve maxed out. Brakes are awesome even with 40" rubber.
Cargo Master
Joined: Sep 2007
Posts: 2,470
Likes: 535
From: Chandler, AZ
I think I missed part of your original question. To minimize changes in lines, you can retain the original distribution block and all the line after it. It does nothing to pressures. Instead of linked Willwood combo distribution/prop unit, get just a adjustable prop valve like this
https://www.wilwood.com/MasterCylind...CylinderValves
and put it in rear circuit between MC and factory distribution block. Then you only have to make 2/3 short lines/hoses.
This is what I did to mine, and left front delay value in place also. But I made all custom lines/hoses also. I added residual valve in rear circuit as well. If your MC has a residual desinged for drum, it will hold more pressure on dicss than you want. not sure if that is really a problem though.
MC is from 1994 F350 to match axles/brakes from same.
https://www.wilwood.com/MasterCylind...CylinderValves
and put it in rear circuit between MC and factory distribution block. Then you only have to make 2/3 short lines/hoses.
This is what I did to mine, and left front delay value in place also. But I made all custom lines/hoses also. I added residual valve in rear circuit as well. If your MC has a residual desinged for drum, it will hold more pressure on dicss than you want. not sure if that is really a problem though.
MC is from 1994 F350 to match axles/brakes from same.
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Tuned
Joined: Mar 2009
Posts: 315
Likes: 8
From: Austin, TX
Thank you that makes a lot of sense. I think I’m going to get the James duff tbird front calipers combined with disc/disc master cylinder, stainless front lines, and proportion valve. They offer a full bundle. Will make the truck stop like a more modern vehicle.
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