Brake codes explained?

[Sean Buick 76]

Hi guys and gals. So my 92 4x4 light duty 2500 6 lug truck has a JB6 code. Does this code determine the brakes front and rear or only the front?

I’m looking to replace the brakes all around and the parts shops don’t seem very good at getting me the right door pin rebuild kit let alone brakes for a bit of an odd ball truck.

Any advice or info for buying the right parts or dealing with clueless parts stores? I’m hoping to buy it all locally to avoid having the wrong parts shipped!

Thanks in advance

 

[Caman96]

I believe front and rear. My 96 K1500 has the same size front brakes as yours, but not having the rear 11” brakes that you have gives me JB5.

 

[Drunkcanuk]

99% sure it's the whole package, front and back.

 

[Caman96]

You must be registered for see images attach

 

[movietvet]

If you also have C5Z RPO code, then you are 7200 lb. GVWR and if you look at RA the pads either ask that or if is 6 lug wheels. Also at RA, the shoes are identified as 6 lug wheels and/or vacuum boost or hydro-boost. I was looking at Genuine GM or AC Delco.

 

[Caman96]

If you also have C5Z RPO code, then you are 7200 lb. GVWR and if you look at RA the pads either ask that or if is 6 lug wheels. Also at RA, the shoes are identified as 6 lug wheels and/or vacuum boost or hydro-boost. I was looking at Genuine GM or AC Delco.

…or on a 1500(truck) you could get RPO 65S with GVW 6600 lb. that would have JB6 brakes(as a bonus you’d have a 9.5 SF).

 

[movietvet]

…or on a 1500(truck) you could get RPO 65S with GVW 6600 lb. that would have JB6 brakes(as a bonus you’d have a 9.5 SF).

That is why, when I am working on any vehicle I have here at my house, I look up all of the options and RPO codes and measure and and and....

IMO, brakes are the most important system on ANY vehicle. I don't care how good it runs, how well it cools, how well it shifts....it has to stop. When I am doing brake work, it is done my way or I pass on the job.

 

[Schurkey]

JB6 is the same as JB5 in front, along with master and booster. The difference is in the rear, JB5 has the crappy 254mm (10") Leading/Trailing shoe rear drums, while JB6 has the infinitely-better 11.x Duo-Servo drums.

All this will be listed in the service manual set for your vehicle that you should download from the Sticky section of this forum. A crappy screenshot of the brake option codes for '97 is attached.

 

[GoToGuy]

Welcome to world of GM's secret code world. Actually it's really cool . The RPO codes are a full explanation of what your vehicle was built with. All options, paint, body, vehicle specs. There are RPO code breakdown list available to download.
Or for the most exact code breakdown, the OE service manual for your year, in section 1 has all the RPO options for that year and what they are. Charts like this for example.

You must be registered for see images attach

 

[Schurkey]

I tried to do that--post a photo of the brake option codes.

Closest I could get was a copy-to-Word Document, and then attach the Word document. My way sucks.

Also--what year service manual did that come from? In '97, JB/JD7 included 2.5" wide rear brakes, not 3.5" wide.

I wish that those charts also included caliper piston diameter, master cylinder and wheel-cylinder sizes.