Brake booster question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

LeesTruk · 07-24-2016, 02:05 PM

I'd like to replace the booster on my C10 (1980). It looks as if at one time a m/c had leaked and was replaced by the previous owner. My dilemma is this. There is no SPID on the glove box door (or anywhere). I have the big 1.25" rotors, 2" brake shoes, and a single diaphragm booster. I'm assuming that's a JB3 setup? I'd like to go to the dual diaphragm booster and am wondering if the two boosters are interchangeable? Thanks

**hatzie** · 07-24-2016, 05:56 PM

You'll probably have to get a Master Cylinder to match the booster.

LeesTruk · 07-24-2016, 07:16 PM

Using Rock Auto as my guide, it shows a 1.125" bore m/c for both the JB3 and JB5 systems, with a 1" bore m/c for manual brakes. Is there something else to choose from?

07-24-2016, 02:05 PM	#1
LeesTruk Registered User Join Date: Mar 2015 Location: Manchester, CT Posts: 433	Brake booster question I'd like to replace the booster on my C10 (1980). It looks as if at one time a m/c had leaked and was replaced by the previous owner. My dilemma is this. There is no SPID on the glove box door (or anywhere). I have the big 1.25" rotors, 2" brake shoes, and a single diaphragm booster. I'm assuming that's a JB3 setup? I'd like to go to the dual diaphragm booster and am wondering if the two boosters are interchangeable? Thanks

07-24-2016, 05:56 PM	#2
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Brake booster question You'll probably have to get a Master Cylinder to match the booster. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-24-2016, 07:16 PM	#3
LeesTruk Registered User Join Date: Mar 2015 Location: Manchester, CT Posts: 433	Re: Brake booster question Using Rock Auto as my guide, it shows a 1.125" bore m/c for both the JB3 and JB5 systems, with a 1" bore m/c for manual brakes. Is there something else to choose from?



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