Disk Brake swap question Master cylinder? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

steves1967 · 11-22-2008, 01:19 AM

My buddy just picked up a 70 shortbed GMC, it had 4 wheel drum brakes. I helped him add the ECE disk brake spindles, rotors, and calipers kit. We have the lines bled correctly but the pedal still goes all the way to the floor, I can see the calipers grabbing the rotor though. Do I need to swap master cylinders?

steves1967 · 11-23-2008, 02:17 AM

C'mon atleast somebody tell me that they are the same M/C and I'm just not that bright....

myoldchevytruck · 11-23-2008, 02:52 AM

Yes you do need to change the Master Cylinder. You also have to use a proportional valve. I just bought a new Bendix Master Cylinder from Advanced Auto for $57.00 There house brand is $39.00 for a new and $19.00 for a reman plus core. Go with a new one.

70 net440 · 11-23-2008, 09:51 AM

My ECE kit came with a new M/C and prop valve.

myoldchevytruck · 11-23-2008, 10:33 AM

Quote:

Originally Posted by 70 net440

My ECE kit came with a new M/C and prop valve.

What was the price of that ECE kit and what's included? Thanks.

70 net440 · 11-23-2008, 02:23 PM

It wasn't cheap. But, high quality stuff. I can't remember the exact price, I also bought a lowering kit. I think the link is www.earlyclassic.com can't seem to find my catalog right now.

glock35ipsc · 11-23-2008, 03:58 PM

Quote:

Originally Posted by steves1967

My buddy just picked up a 70 shortbed GMC, it had 4 wheel drum brakes. I helped him add the ECE disk brake spindles, rotors, and calipers kit. We have the lines bled correctly but the pedal still goes all the way to the floor, I can see the calipers grabbing the rotor though. Do I need to swap master cylinders?

Yes, you do. The main difference between drum/drum and disc/drum MC's are the size of the reservoirs. The drum/drum reservoirs are equal sizes, and the disc/drum have a larger front reservoir. The disc calipers hold a larger volume of fluid then the drum brake cylinders, hence the larger reservoir.

The "distribution valve" on the drum/drum set-up does just, distribute fluid equally to all four wheel cylinders. On a disc/drum set-up, the "proportioning valve" distributes the fluid in different proportions to the front (disc) and rear (drum). Some are even adjustable to get the right amount of grab front and rear.

DennisL · 11-24-2008, 01:56 AM

Glock is right. Drum m/c for drum brakes and Disc m/c for disc brakes. You'll need that prop valve too.

phipp13 · 11-24-2008, 03:05 AM

not only do you need a prop valve but ,i believe the reason why you have no pedal is because you may have neglected to bleed the master cylander. also i'm almost positive the piston bore in the M/C is a larger bore size for disc brakes

LuckyHenriksen · 11-24-2008, 03:24 AM

My disc/drum setup works well with the stock drum/drum MC, but now I am worried. I'll just keep an eye on it.

11-22-2008, 01:19 AM	#1
steves1967 Registered User Join Date: Dec 2001 Location: Manteca, Ca USA Posts: 305	Disk Brake swap question Master cylinder? My buddy just picked up a 70 shortbed GMC, it had 4 wheel drum brakes. I helped him add the ECE disk brake spindles, rotors, and calipers kit. We have the lines bled correctly but the pedal still goes all the way to the floor, I can see the calipers grabbing the rotor though. Do I need to swap master cylinders? __________________ '71 Chevy 3/4 Ton Longbed '22 Chevy Tahoe RST '67 Firebird- 8 sec street car '24 GMC CC 4x4 Duramax Dually

11-23-2008, 02:17 AM	#2
steves1967 Registered User Join Date: Dec 2001 Location: Manteca, Ca USA Posts: 305	Re: Disk Brake swap question Master cylinder? C'mon atleast somebody tell me that they are the same M/C and I'm just not that bright.... __________________ '71 Chevy 3/4 Ton Longbed '22 Chevy Tahoe RST '67 Firebird- 8 sec street car '24 GMC CC 4x4 Duramax Dually

11-23-2008, 02:52 AM	#3
myoldchevytruck Retired Air Force Veteran Join Date: Aug 2007 Location: Pembroke Pines, Florida 33024 Posts: 1,808	Re: Disk Brake swap question Master cylinder? Yes you do need to change the Master Cylinder. You also have to use a proportional valve. I just bought a new Bendix Master Cylinder from Advanced Auto for $57.00 There house brand is $39.00 for a new and $19.00 for a reman plus core. Go with a new one. __________________ Harry 69' SWB Step Side 1/2 Ton w/68' Front Clip Swap from Leafs to Trailing Arms (Complete) Swap 6 Lug to 5 Lug (w/ Disk Brakes in Front) 3/6 Drop Help Support The Board Click Here For Information On How To Subscribe Krue's FAQ Page Vendors Last edited by myoldchevytruck; 11-23-2008 at 02:53 AM.

11-23-2008, 09:51 AM	#4
70 net440 Junior Member Join Date: Sep 2003 Location: yreka, ca Posts: 270	Re: Disk Brake swap question Master cylinder? My ECE kit came with a new M/C and prop valve. __________________ 63 C10 70 Coronet R/T 67 C10 70 Dart Swinger 71 K10

11-23-2008, 02:23 PM	#6
70 net440 Junior Member Join Date: Sep 2003 Location: yreka, ca Posts: 270	Re: Disk Brake swap question Master cylinder? It wasn't cheap. But, high quality stuff. I can't remember the exact price, I also bought a lowering kit. I think the link is www.earlyclassic.com can't seem to find my catalog right now. __________________ 63 C10 70 Coronet R/T 67 C10 70 Dart Swinger 71 K10

11-24-2008, 01:56 AM	#8
DennisL Registered User Join Date: Feb 2007 Location: Kaleefornia Posts: 15	Re: Disk Brake swap question Master cylinder? Glock is right. Drum m/c for drum brakes and Disc m/c for disc brakes. You'll need that prop valve too. __________________ shade tree mechanic, 68 chev stepside, 350 w turbo 400 & GMC front clip, Factory Five Cobra, 29 model A with 289 w C-4, 68 Barracuda Fastback w/360

11-24-2008, 03:05 AM	#9
phipp13 THE DAMN YANKEE Join Date: Sep 2006 Location: Southern MD Posts: 551	Re: Disk Brake swap question Master cylinder? not only do you need a prop valve but ,i believe the reason why you have no pedal is because you may have neglected to bleed the master cylander. also i'm almost positive the piston bore in the M/C is a larger bore size for disc brakes

11-24-2008, 03:24 AM	#10
LuckyHenriksen Registered User Join Date: Oct 2007 Location: Sherwood Oregon Posts: 1,908	Re: Disk Brake swap question Master cylinder? My disc/drum setup works well with the stock drum/drum MC, but now I am worried. I'll just keep an eye on it. __________________ 1968 Yenko Chevy LWB 6.0L/TH400 3/4 Drop Senior Project Build Thread Here



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