1972 C60 Master Cylinder size help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

eodcoduto · 07-31-2022, 08:17 PM

I can find most answers to my questions with the search function and Googling stuff, but I am stuck on this. I have a '72 C60 that is about back on the road, rebuilt the 366 and now I am working on the brakes. The master cylinder is shot, a rehone didn't help and I can't find a rebuild kit anywhere, so I am ready to get a new one. Now the issue is the master cylinder that I took off is a 1.5" bore, which should be right for a F070 7,500lb front axle, but I also have the 9000# spring option with a 23,000lb rear axle. So should this have the 1.75" bore master? Here is my RPO sheet, and any help is appreciated.

This is a 55K mile truck without rust and it is getting put back to work hauling bales and wood chips.

eodcoduto · 08-05-2022, 12:08 PM

I found the master cylinder and things are bled properly now, but the hydrovac isn't working so I am searching for a replacement.

**Bob B.** · 08-06-2022, 01:53 AM

Is it a dual unit? If so, take a look at a NAPA NBB518009.

eodcoduto · 08-06-2022, 04:55 PM

Quote:

Originally Posted by Bob B.

Is it a dual unit? If so, take a look at a NAPA NBB518009.

No its a single unit, I am sending it to Cardone for and R&R on Monday. New wheel cylinders will go in as well so other than a couple of hard lines the brake system will be new.
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07-31-2022, 08:17 PM	#1
eodcoduto Registered User Join Date: Jul 2017 Location: Twentynine Palms, Ca Posts: 16	1972 C60 Master Cylinder size help I can find most answers to my questions with the search function and Googling stuff, but I am stuck on this. I have a '72 C60 that is about back on the road, rebuilt the 366 and now I am working on the brakes. The master cylinder is shot, a rehone didn't help and I can't find a rebuild kit anywhere, so I am ready to get a new one. Now the issue is the master cylinder that I took off is a 1.5" bore, which should be right for a F070 7,500lb front axle, but I also have the 9000# spring option with a 23,000lb rear axle. So should this have the 1.75" bore master? Here is my RPO sheet, and any help is appreciated. This is a 55K mile truck without rust and it is getting put back to work hauling bales and wood chips. Attached Images

08-05-2022, 12:08 PM	#2
eodcoduto Registered User Join Date: Jul 2017 Location: Twentynine Palms, Ca Posts: 16	Re: 1972 C60 Master Cylinder size help I found the master cylinder and things are bled properly now, but the hydrovac isn't working so I am searching for a replacement.

08-06-2022, 01:53 AM	#3
Bob B. Senior Member Join Date: Aug 2005 Location: Los Angeles Posts: 1,348	Re: 1972 C60 Master Cylinder size help Is it a dual unit? If so, take a look at a NAPA NBB518009. __________________ 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.



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