booster upgrade, MC compatability? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

shelby987 · 01-11-2006, 11:37 AM

I am going to be putting pb on my 70 3/4t and wanted to check, does the MC need to be changed, or is there no difference between a manual and power brake MC? Is there a different booster for a 3/4t vs. 1/2t?
Anything else I should be concerned with.....I recently had to replace the MC on my daily olds. and it was relatively cheap, would I be better off to just swap my manual as a core for a new one?
Does a booster have to be rebuilt at all?
Any year interchange ability issues, or will all 67-72's work?
Thanks

Longhorn Man · 01-11-2006, 11:42 AM

master cylinder is the same P/N power to non power as long as you are staying in the same series. 10 model and 20 model don't interchainge... but power to non power on a 20 is good.

The booster, you'll want a 20 series or a 30 series.

72MARIO · 01-11-2006, 01:26 PM

Are you sure ? I thought they were diffirent boar size....

67ChevyRedneck · 01-11-2006, 01:57 PM

Front disk brakes vs front and rear drum brakes do have a different bore size. The disk brake MC has a larger front and smaller rear reservior. The drum brakes have equal sized reserviors. I think SHELBY987 just wants to upgrade his drum brakes from non-power to power, so the MC will be the same. If he wanted to add disks as well, the MC's would be different.

**Bob B.** · 01-11-2006, 02:42 PM

I believe on 1967-70, the 1/2 tons had a 1 inch bore master cylinder, and the 3/4 tons had a 1 1/8th. bore. They look the same from the outside.

Longhorn Man · 01-11-2006, 02:48 PM

I am sorry, there is a difference betwqeen 67 - 70, and 71/72.
However, for one truck, the p/n is the same for the master, regardless if there is a booster there or not.

shelby987 · 01-11-2006, 03:03 PM

ok, let me see if I have received all of this information correctly....I can keep my MC (power or manual, same thing) since I will be keeping my drums 4 corners. But to upgrade to power brakes, I need a booster from a 20/30 series truck, is this correct?
Thanks

Longhorn Man · 01-11-2006, 03:18 PM

Yep. you got it. A booster off a 67 - 70 20/30 series truck.

72MARIO · 01-12-2006, 01:26 AM

Oky, I am glad I got that cleared up. I thought I might have gotten the wrong master cyl for my 72 but I guess there is only one avaible so I have the right one. The manual brakes sure do give the leg a work out after driving a power brake car or truck.

01-11-2006, 11:37 AM	#1
shelby987 Registered User Join Date: Mar 2005 Location: Just outside Durham, NC Posts: 894	booster upgrade, MC compatability? I am going to be putting pb on my 70 3/4t and wanted to check, does the MC need to be changed, or is there no difference between a manual and power brake MC? Is there a different booster for a 3/4t vs. 1/2t? Anything else I should be concerned with.....I recently had to replace the MC on my daily olds. and it was relatively cheap, would I be better off to just swap my manual as a core for a new one? Does a booster have to be rebuilt at all? Any year interchange ability issues, or will all 67-72's work? Thanks __________________ 1969 SS 350 Camaro Sold 2008 1970 3/4T K20, stock height with 33's, 250 I6, 3 on the tree, and locked front and rear 4.10's 1980 Chevy Malibu 2 dr Sold 2007 1993 Olds. Cutlass Ciera Wagon Traded 2006 2003 Saturn L200 w/5pd. D/D My list spans 5 decades with One common thread.....GM!

01-11-2006, 11:42 AM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: booster upgrade, MC compatability? master cylinder is the same P/N power to non power as long as you are staying in the same series. 10 model and 20 model don't interchainge... but power to non power on a 20 is good. The booster, you'll want a 20 series or a 30 series.

01-11-2006, 01:26 PM	#3
72MARIO Registered User Join Date: Nov 2000 Location: Huntsville Ontario Canada Posts: 4,051	Re: booster upgrade, MC compatability? Are you sure ? I thought they were diffirent boar size.... __________________ 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

01-11-2006, 01:57 PM	#4
67ChevyRedneck Hittin E-Z Street on Mud Tires Join Date: Nov 2004 Location: Greenville, SC Posts: 23,090	Re: booster upgrade, MC compatability? Front disk brakes vs front and rear drum brakes do have a different bore size. The disk brake MC has a larger front and smaller rear reservior. The drum brakes have equal sized reserviors. I think SHELBY987 just wants to upgrade his drum brakes from non-power to power, so the MC will be the same. If he wanted to add disks as well, the MC's would be different. __________________ Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride American Born, Country by the Grace of God 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications!

01-11-2006, 02:42 PM	#5
Bob B. Senior Member Join Date: Aug 2005 Location: Los Angeles Posts: 1,369	Re: booster upgrade, MC compatability? I believe on 1967-70, the 1/2 tons had a 1 inch bore master cylinder, and the 3/4 tons had a 1 1/8th. bore. They look the same from the outside. __________________ 1967 GMC CM-2500 Camper Cruiser, 351E V-6, NP 435 4 speed, Dana 60, and factory A/C. 2012 GMC K-3500 WT regular cab, 6.0L Vortec, 6L90.

01-11-2006, 02:48 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: booster upgrade, MC compatability? I am sorry, there is a difference betwqeen 67 - 70, and 71/72. However, for one truck, the p/n is the same for the master, regardless if there is a booster there or not.

01-11-2006, 03:03 PM	#7
shelby987 Registered User Join Date: Mar 2005 Location: Just outside Durham, NC Posts: 894	Re: booster upgrade, MC compatability? ok, let me see if I have received all of this information correctly....I can keep my MC (power or manual, same thing) since I will be keeping my drums 4 corners. But to upgrade to power brakes, I need a booster from a 20/30 series truck, is this correct? Thanks __________________ 1969 SS 350 Camaro Sold 2008 1970 3/4T K20, stock height with 33's, 250 I6, 3 on the tree, and locked front and rear 4.10's 1980 Chevy Malibu 2 dr Sold 2007 1993 Olds. Cutlass Ciera Wagon Traded 2006 2003 Saturn L200 w/5pd. D/D My list spans 5 decades with One common thread.....GM!

01-11-2006, 03:18 PM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: booster upgrade, MC compatability? Yep. you got it. A booster off a 67 - 70 20/30 series truck.

01-12-2006, 01:26 AM	#9
72MARIO Registered User Join Date: Nov 2000 Location: Huntsville Ontario Canada Posts: 4,051	Re: booster upgrade, MC compatability? Oky, I am glad I got that cleared up. I thought I might have gotten the wrong master cyl for my 72 but I guess there is only one avaible so I have the right one. The manual brakes sure do give the leg a work out after driving a power brake car or truck. __________________ 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

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