Master Cylinder Questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

WITHOUT_REASON · 06-16-2004, 06:37 PM

Got a 68 SWB that I just converted to disc brakes I took from a 71 my question is has anyone ever used a master cylinder from a 84 to 87 model truck ( Aluminum type), will it produce the correct fluid & pressure amounts to make my brakes work properly, or would I be better off using the cast iron style master cylinder from a 71 through 78 or so?

krue · 06-16-2004, 07:14 PM

I am sure it can be done, with a little modding. BTW welcome to the board from South Mississippi!

LONGHAIR · 06-16-2004, 07:26 PM

The pressure produced is basically related to the diameter of the bore. If you are close to the same size there you should be good. Just be aware that you need a proportioning valve for the disc brake set-up. There is a check-valve in the drum system that keeps some pressure on the wheel cylinders of the drums. They have springs to force the fluid back, discs do not and cannot stand the residual pressure.

Tx Firefighter · 06-16-2004, 08:15 PM

Another board member here did just that. I can't ever remember his name though. He used like an 85 model master cylinder.

06-16-2004, 06:37 PM	#1
WITHOUT_REASON Registered User Join Date: May 2004 Location: Kentucky Posts: 5	Master Cylinder Questions Got a 68 SWB that I just converted to disc brakes I took from a 71 my question is has anyone ever used a master cylinder from a 84 to 87 model truck ( Aluminum type), will it produce the correct fluid & pressure amounts to make my brakes work properly, or would I be better off using the cast iron style master cylinder from a 71 through 78 or so?

06-16-2004, 07:14 PM	#2
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	I am sure it can be done, with a little modding. BTW welcome to the board from South Mississippi! __________________ "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"

06-16-2004, 08:15 PM	#4
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Another board member here did just that. I can't ever remember his name though. He used like an 85 model master cylinder. __________________ I'm on the Instagram- @Gearhead_Kevin

06-16-2004, 07:26 PM	#3
LONGHAIR just can't cover up my redneck Join Date: May 2004 Location: Columbus OH Posts: 11,414	The pressure produced is basically related to the diameter of the bore. If you are close to the same size there you should be good. Just be aware that you need a proportioning valve for the disc brake set-up. There is a check-valve in the drum system that keeps some pressure on the wheel cylinders of the drums. They have springs to force the fluid back, discs do not and cannot stand the residual pressure.



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