What's the difference in master cylinders? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

krue · 04-24-2003, 09:05 PM

What's the difference between manual and power brake master cylinders. Both are drum/ drum. The manual one that is on the truck looks like a pre-67 m/c (has bolted on lid). The business end of both look identical as far as where the rod goes.

If there is any significant difference what's the best way to clean a master cylinder with rust in it?

*rage'nrat638* · 04-24-2003, 09:56 PM

piston size in side......if theres rust inside don't think i would trust it....seals may be shot????or will be as soon as you put on the brakes......make sure the e brake works......

kaycee · 04-24-2003, 10:28 PM

Auto STONE OR similer auto store and get a new 1 for under $ 20

krue · 04-25-2003, 06:28 PM

I went to get one at autozone and they only differentiate between drum/drum and disc/drum not between manual and power? Should I get one from a different year?

Longhorn Man · 04-25-2003, 08:21 PM

On these ones there is no power or manual style..they are the same.
At least that's what the part numbers come up with at all the major parts chains I have tried. I have bought 3 masters so far (one for each truck I have owned) and no trouble as of yet. (one was manual, and the other 2 power)

krue · 04-25-2003, 08:43 PM

Thanx man, that's what I figured, but you can never be too sure.

70c10 · 04-25-2003, 08:51 PM

Does it matter whether it's the shorter car type or taller truck type?. My master cylinder is shallower than my dad's.

Longhorn Man · 04-25-2003, 08:55 PM

Hmmm, that is a good Q that I can't answer very well, but I will say that if it is on your truck, and you are not having any trouble...I'd run it.
The part you are questioning is nothing more than a resivour.
Is your dad's equipped with discs> They are a bit bigger than the drum ones.

70c10 · 04-26-2003, 11:56 AM

Nope. He's got power drums like me. His is the taller truck resevoir that I believe was from a disc truck originally. I need a new one and thought maybe a taller one would work better.

Southpa · 04-26-2003, 08:54 PM

I've used three types of M/C and 2 boosters and never had problems with mounting and installation. Originally, the truck had a power drum/drum system. Then I swapped front ends with a 71 that had manual disc/drum system, and used that M/C. It worked fine but was the type with one hold down clip along the length (early model Delco) and leaked out the cap. Then I traded it in for a reman of the same kind, that leaked out the cap too. Then I traded that in for a double hold down clip (Bendix) and it works fine and doesn't leak. I also swapped my 1/2 ton brake booster for a 3/4 ton booster. Installed fine and works great.

Out of all that I haven't come across any differences in piston size or rod size or whatever, they are pretty much all interchangeable aside from the differences between power and manual brakes.

04-24-2003, 09:05 PM	#1
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,448	What's the difference in master cylinders? What's the difference between manual and power brake master cylinders. Both are drum/ drum. The manual one that is on the truck looks like a pre-67 m/c (has bolted on lid). The business end of both look identical as far as where the rod goes. If there is any significant difference what's the best way to clean a master cylinder with rust in it? __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

04-24-2003, 10:28 PM	#3
kaycee Registered User Join Date: Jan 2000 Location: Wyoming USA Posts: 2,453	LOOK AT Auto STONE OR similer auto store and get a new 1 for under $ 20 __________________ 2001 Silverado K-1500 2005 FXDWG stage3 69 CHEVY Short/Step 327/4L60 373 posi 63 IMPALA 327/4L60

04-25-2003, 06:28 PM	#4
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,448	I went to get one at autozone and they only differentiate between drum/drum and disc/drum not between manual and power? Should I get one from a different year? __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

04-25-2003, 08:43 PM	#6
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,448	Thanx man, that's what I figured, but you can never be too sure. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

04-25-2003, 08:51 PM	#7
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Does it matter whether it's the shorter car type or taller truck type?. My master cylinder is shallower than my dad's. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

04-24-2003, 09:56 PM	#2
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	piston size in side......if theres rust inside don't think i would trust it....seals may be shot????or will be as soon as you put on the brakes......make sure the e brake works......

04-25-2003, 08:21 PM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	On these ones there is no power or manual style..they are the same. At least that's what the part numbers come up with at all the major parts chains I have tried. I have bought 3 masters so far (one for each truck I have owned) and no trouble as of yet. (one was manual, and the other 2 power)

04-25-2003, 08:55 PM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Hmmm, that is a good Q that I can't answer very well, but I will say that if it is on your truck, and you are not having any trouble...I'd run it. The part you are questioning is nothing more than a resivour. Is your dad's equipped with discs> They are a bit bigger than the drum ones.

04-26-2003, 11:56 AM	#9
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Nope. He's got power drums like me. His is the taller truck resevoir that I believe was from a disc truck originally. I need a new one and thought maybe a taller one would work better. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

04-26-2003, 08:54 PM	#10
Southpa Registered User Join Date: May 2000 Location: Victoria, BC, Canada Posts: 2,409	I've used three types of M/C and 2 boosters and never had problems with mounting and installation. Originally, the truck had a power drum/drum system. Then I swapped front ends with a 71 that had manual disc/drum system, and used that M/C. It worked fine but was the type with one hold down clip along the length (early model Delco) and leaked out the cap. Then I traded it in for a reman of the same kind, that leaked out the cap too. Then I traded that in for a double hold down clip (Bendix) and it works fine and doesn't leak. I also swapped my 1/2 ton brake booster for a 3/4 ton booster. Installed fine and works great. Out of all that I haven't come across any differences in piston size or rod size or whatever, they are pretty much all interchangeable aside from the differences between power and manual brakes. Attached Images __________________ 1970 GMC 1500 Custom Original 350/TH350 Victoria, BC, Canada You can wish in one hand and crap in the other. See which one gets filled first.



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