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#1 |
Registered User
Join Date: Apr 2005
Location: Columbus, OH
Posts: 197
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master cylinder question - drum/drum to disc/drum???
As you may have read elsewhere on here, I am doing my brake upgrades in phases with my 62 that has the combo brake/clutch master cylinder. For now, I am divorcing the clutch and brake cylinders, mounting a new clutch cylinder in the stock linkage location, and adding a power booster with custom brackets that will space it off the firewall far enough to clear a clutch master, and the at the same time, adding a dual circuit brake master. For now, I will stick with a drum/drum master, as swapping the crossmember for discs will take a lot more time than I have at the moment. I was planning on using this drum/drum master:
1967 GMC C35/C3500 PICKUP 5.4L 327cid V8 DORMAN M66787 1-1/8" bore Master Cylinder I figured at the very least, when I swap to discs, I could get one of these old style power brake disc/drum masters (still has the old deep bore pushrod hole, works with same booster type as I will already have) 1972 GMC C15/C1500 SUBURBAN 5.7L 350cid V8 (E) Master Cylinder DORMAN Part # M80568 More Info {First Stop #3491500, 3821715, 4089212, 436148C92, 6273936}w/Manual or Power Brakes; Bore = 1-1/8"; Bendix NOW, what I was wondering, was first off, I think the master that I have on order for drum/drum is going to have residual valves internally like my 62 master does for the brake portion. If not, and a 67 had them inline or in a metering block/prop valve, someone speak up please! I was thinking, that since the bores are going to be the same diameter for drum/drum over to disc/drum, could I just keep this master cylinder and disassemble it and remove one of the two residual check valves internal to the master, and use it as a disc/drum master by just simply adding a disc/drum proportioning valve? Is there something that I don't know that will keep this from working well? Two other lesser questions, is it the norm for a hydraulic system to still use the same proportions for master cylinder bore vs caliper/wheel cylinder bore diameters, regardless of power or manual brakes????? I figured since my manual brakes and clutch both use a 1-1/8" bore master, that power brakes and same clutch would still both need 1-1/8" Also, our trucks stock (my 62) has no metering block or proportioning valve. I assume they never came with them, and that I also won't need one when switching to a dual circuit with drum/drum, correct? It would really make sense that in any system, you would want less fluid/power to the rear vs the fronts, but it seems that it's only a real life issue when discussing drum/disc or disc/disc setups. Should I add a proportioning valve when I swap to a dual circuit setup?
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Chuck in Ohio *1962 GMC 1000 Panel Truck - 305D/Saginaw 4sp soon: 351C V6 + AX15 5sp OD trans, & 75-87/91 disc brake front end *1988 Suzuki Samurai 4x4 project, VW 1.9L mTDI, Toyota R151F transmission & Toyota full floater axles, LWB body tub stretch project *Many 1977-1979 Suzuki GS motorcycles, Kawasaki KDX220R, '77 Suzuki PE250, etc |
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