Which brakes, JD6/JD7? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

VTKidder · 02-12-2007, 10:14 AM

On my 1986 K20, I need to replace nearly every brake componenet except the booster and MC. I looked up the calipers, and I get the option for JD6/JB6 or JD7/JB7 brake system. The description says it'll show on the RPO label in the glovebox, but that is long-gone. Does one code mean a certain size rotor, or something you can visually tell? Thanks.

-adam

beaterC10 · 02-12-2007, 09:02 PM

Normally the best way to id your brake option is the thickness of rotor and the width of the rear shoes. I don't know what codes correspond to what size, but the parts stores normally can match up with rotors and shoes.

boxrodz · 02-12-2007, 10:35 PM

The rotors on both systems (JB6 & JB7) are the same dimensions. However, the dimensions of the rear drums are different. The JB6 drums are 11.15 x 2.75 whereas the JB7 drums are larger at 13 x 2.5.

VTKidder · 02-13-2007, 07:49 AM

Thank you for the info guys....when I look up the part number on the calipers for JB6 and 7, they are different. Any clue what the difference is?

*CookieMonster* · 02-13-2007, 10:14 AM

cause the front rotors are either 1 inch thick, or 1.25 inches thick.

boxrodz · 02-14-2007, 01:52 AM

Actually, the thickness of the rotors are the same for both systems. The difference is that the JB6 is a low drag system and the JB7 is a conventional brake system.

02-12-2007, 10:14 AM	#1
VTKidder Registered User Join Date: May 2003 Location: Vermont Posts: 996	Which brakes, JD6/JD7? On my 1986 K20, I need to replace nearly every brake componenet except the booster and MC. I looked up the calipers, and I get the option for JD6/JB6 or JD7/JB7 brake system. The description says it'll show on the RPO label in the glovebox, but that is long-gone. Does one code mean a certain size rotor, or something you can visually tell? Thanks. -adam Last edited by VTKidder; 02-12-2007 at 12:22 PM.

02-12-2007, 09:02 PM	#2
beaterC10 Senior Member Join Date: Jul 2003 Location: Indianapolis, IN Posts: 1,277	Re: Which brakes, JD6/JD7? Normally the best way to id your brake option is the thickness of rotor and the width of the rear shoes. I don't know what codes correspond to what size, but the parts stores normally can match up with rotors and shoes.

02-12-2007, 10:35 PM	#3
boxrodz Until Seventy Times Seven Join Date: Feb 2005 Location: Rocky Mountain Front Range Posts: 1,301	Re: Which brakes, JD6/JD7? The rotors on both systems (JB6 & JB7) are the same dimensions. However, the dimensions of the rear drums are different. The JB6 drums are 11.15 x 2.75 whereas the JB7 drums are larger at 13 x 2.5. __________________ boxRODz 1983 C10 SWB Fleetside When two halves is gone, there's nuthin left. Two nothings is nuthin. That's mathematics son. You can argue with me but you can't argue with figures. Two half nothings is a whole nuthin...

02-13-2007, 07:49 AM	#4
VTKidder Registered User Join Date: May 2003 Location: Vermont Posts: 996	Re: Which brakes, JD6/JD7? Thank you for the info guys....when I look up the part number on the calipers for JB6 and 7, they are different. Any clue what the difference is?

02-13-2007, 10:14 AM	#5
CookieMonster Account Suspended Join Date: Feb 2007 Location: Headingly, Manitoba Posts: 4	Re: Which brakes, JD6/JD7? cause the front rotors are either 1 inch thick, or 1.25 inches thick.

02-14-2007, 01:52 AM	#6
boxrodz Until Seventy Times Seven Join Date: Feb 2005 Location: Rocky Mountain Front Range Posts: 1,301	Re: Which brakes, JD6/JD7? Actually, the thickness of the rotors are the same for both systems. The difference is that the JB6 is a low drag system and the JB7 is a conventional brake system. __________________ boxRODz 1983 C10 SWB Fleetside When two halves is gone, there's nuthin left. Two nothings is nuthin. That's mathematics son. You can argue with me but you can't argue with figures. Two half nothings is a whole nuthin... Last edited by boxrodz; 02-14-2007 at 12:12 PM. Reason: Typo



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