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

RAGIN68 · 04-29-2002, 02:03 PM

I just called the parts store checking on coil springs for my 68. My front-end parts are from a 85 and they asked me if I have a "J3" or a "J5 brake system. I dont have a clue! Do any of yall know what they are asking about???

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68GMC SWB Gound-up restoration,
350/700R4/??? 2002 3/4 HD for a daily driver. Can't get away from the GMs

*Fast68Chevy* · 04-29-2002, 02:36 PM

they always ask that, its RPO code i thnk oyu mean JB3 or JB5
I iwll see if I can find info online regarding this, I am curious to know also. been needing to find out,

JJR · 04-29-2002, 06:52 PM

It should not matter what brakes you have. Basically all 2WD 1/2 and 3/4 ton front springs from the mid 60's to early 90's will interchange. The only difference is spring rate. My guess is one of those brake codes is for heavy duty brakes which may have come with HD front springs. Ask the parts guys if they show the spring rate for the two brake systems and pick the lighter if you want a smoother ride.

JJR · 04-30-2002, 07:51 AM

FYI. Looked on Hollanders: JB3 is power disc brakes with 11.86X1.04" rotors and 11X2" drum brake shoes(used 76-96). JB5 is power disc brakes with 11.86X1.29" rotors and 11.15X2.75" drum brake shoes(used 76-98).

RAGIN68 · 04-30-2002, 10:09 AM

Thanks for the info. Sounds like a lot of info.that a lot of folks didnt know

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68GMC SWB Gound-up restoration,350/700R4/???2002 3/4 HD for a daily driver. Can't get away from the GMs

04-29-2002, 02:03 PM	#1
RAGIN68 Registered User Join Date: Apr 2002 Location: Houston Posts: 28	Brake identification I just called the parts store checking on coil springs for my 68. My front-end parts are from a 85 and they asked me if I have a "J3" or a "J5 brake system. I dont have a clue! Do any of yall know what they are asking about??? ------------------ 68GMC SWB Gound-up restoration, 350/700R4/??? 2002 3/4 HD for a daily driver. Can't get away from the GMs __________________ 68GMC SWB Gound-up restoration,350/700R4/????.... 2002 3/4 HD for a daily driver. Can't get away from the GMs

04-29-2002, 06:52 PM	#3
JJR Registered User Join Date: Apr 2000 Location: Leesburg, GA Posts: 746	It should not matter what brakes you have. Basically all 2WD 1/2 and 3/4 ton front springs from the mid 60's to early 90's will interchange. The only difference is spring rate. My guess is one of those brake codes is for heavy duty brakes which may have come with HD front springs. Ask the parts guys if they show the spring rate for the two brake systems and pick the lighter if you want a smoother ride. __________________ FOUNDING MEMBER OF THE DRUM BRAKE CLUB Second Owner 70 C-10 Second Owner 93 GMC C1500 Third Owner 99 C2500 Crew Cab Short Bed

04-30-2002, 07:51 AM	#4
JJR Registered User Join Date: Apr 2000 Location: Leesburg, GA Posts: 746	FYI. Looked on Hollanders: JB3 is power disc brakes with 11.86X1.04" rotors and 11X2" drum brake shoes(used 76-96). JB5 is power disc brakes with 11.86X1.29" rotors and 11.15X2.75" drum brake shoes(used 76-98). __________________ FOUNDING MEMBER OF THE DRUM BRAKE CLUB Second Owner 70 C-10 Second Owner 93 GMC C1500 Third Owner 99 C2500 Crew Cab Short Bed

04-30-2002, 10:09 AM	#5
RAGIN68 Registered User Join Date: Apr 2002 Location: Houston Posts: 28	Thanks for the info. Sounds like a lot of info.that a lot of folks didnt know ------------------ 68GMC SWB Gound-up restoration,350/700R4/???2002 3/4 HD for a daily driver. Can't get away from the GMs __________________ 68GMC SWB Gound-up restoration,350/700R4/????.... 2002 3/4 HD for a daily driver. Can't get away from the GMs

04-29-2002, 02:36 PM	#2
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	they always ask that, its RPO code i thnk oyu mean JB3 or JB5 I iwll see if I can find info online regarding this, I am curious to know also. been needing to find out,



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