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#1 |
Blue 67
![]() Join Date: Apr 2004
Location: Western WA
Posts: 1,178
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proportioning valve question
Hi guys;
I have drums all around with power booster. I plan to go with front disk. When I do that, can I just change the proportioning valve or I have to change the whole master/booster and propotioning valve? Thannks |
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#2 |
Registered User
Join Date: Jul 2004
Location: Northern Nevada
Posts: 156
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Nima,
The prop valve and master cyclinder will be need to be switched. But I believe the booster should be OK.....I think.
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'72 C10 lwb 454/TH400 |
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#3 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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There are plenty here who never chainged any of that, and say it works fine.
However, from a mechanical point of view, you do need to replace all the items you mentioned with parts made for a disc/drum set up. |
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#4 |
Blue 67
![]() Join Date: Apr 2004
Location: Western WA
Posts: 1,178
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Thanks for info. I guess it is better to change them since I don't know how old are these current parts although money is always an issue. Thanks again.
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#5 |
Registered User
Join Date: Jan 2004
Location: NH
Posts: 2,266
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Drum brakes weigh less than disk brakes unless you spend some serious money on lightweight rotors & calipers, If there is no real serious reason for doing frequent high speed stops drum brakes work just fine. Most all of your current parts, wheel cylinders, brake boosters, master cylinders, shoes, and drums can pretty much be gotten at any parts store. I put new drums on the rear last year and got them from NAPA for about $26 each.
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1967 C10 - SWBSS Pro Street 427sbc, 700R4 & 4.10 Gears 1948 Chevy FleetMaster Coupe, LS1, (almost done) 1950 Chevy StyleLine Coupe 250/6 3x2 Dueces 2009 Toyota Tundra 1996 Harley RoadKing "I maybe getting old, but I can still burn rubber with the best of them" |
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#6 |
Registered User
Join Date: Nov 2004
Location: Central Ohio
Posts: 215
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IF your stock parts are all working as designed I'm pretty sure there should be residual pressure being held on the drum circuits, I'd also wonder if the bias is a wee bit different on drum/drum vs disc/drum ?
Residual pressure on calipers = dragging brakes. In disc/drum the front disc circuit is normally held off (delayed) a bit to allow the drums to energize as well. I'm thinking you best do master cylinder AND combo valve if you swap to disc's on the front IMHO Disc brakes do better with water/mud etc., don't have balky alledged self adjusters seizing up and in the case of my ho52 finding rear drums can be a real PITA. So I would argue that there are compelling reasons for such a swap.
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71 K20 350/350/205, dealer air, 4" lift, Flowtech,Edel 1406 on 2101, procomp HEI,4.10's, 33x12.50x16.5 BFG MT's on slots. 4 wheel disc brakes. My lame K20 page My lame Eaton disc brake page ![]() |
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#7 |
Registered User
Join Date: May 2005
Location: South Mississippi
Posts: 81
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Get a master cylinder for a '72 to '86 with the factory proportioning valve. Bolts right up. The disc need the disc/drum master for two reasons, 1) the volume needed for the disc is more 2) the disc portion of the master does not have a residual valve in it. If you use the drum/drum master you must drill out the residual valve and if you have a fluid problem with the front you may not see it in time before it becomes a safety factor. My 2 cents
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#8 |
Registered User
Join Date: Nov 2000
Location: Huntsville Ontario Canada
Posts: 4,052
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You can get a adjustable prop valve. Run the front line right out of the master and T it off to the disks. Run the adjustable porp valve in the rear line. That's what I have done. I dont have the exhaust hooked up yet so I cant tell you how welll it works. Should be perfect though. Use a master for the correct application they are diffierent for a good reason. You cant use a Drum/ Drum master for a Disk/ Drum setup like Rain Fade mentioned. The boster can stay.
Later,
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1968 Suburban numbers matching all original truck now equipped with 6.0/4L80 on Accuair http://67-72chevytrucks.com/vboard/s...d.php?t=625017 1967 C/20 6.0/4L80 Roofing Truck 1990 V2500 Suburban "Plow Truck" 2005 TAHOE DD Last edited by 72MARIO; 05-25-2005 at 06:57 PM. |
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