RPO J55

[f6john]

My 85 C10 has the above “heavy duty brakes”. What I’m wondering is, how do these differ parts wise? My front calipers are dragging and I’m going to replace them and the hoses.

 

[bucket]

The HD brakes use thicker rotors. Iirc, standard is 1" and HD is 1 1/4".

 

[bucket]

And obviously, the calipers are wider to match the rotors.

 

[HotRodPC]

Probably the difference of JB5 and JB6. I do believe 10/1500's got JB5's unless they were Big 10, Heavy Half or probably this option you're speaking of. It's likely the same brakes that were standard on the Big 10 and Heavy Half trucks. But' I'm not swearing to nuttin' !!!

 

[f6john]

Thanks guys. I decided to go ahead and pull off the calipers so I can take them in with me to hopefully get the correct replacements. I didn’t get a good vibe when I went to the parts stores checking on price and availability.

 

[bucket]

Probably the difference of JB5 and JB6. I do believe 10/1500's got JB5's unless they were Big 10, Heavy Half or probably this option you're speaking of. It's likely the same brakes that were standard on the Big 10 and Heavy Half trucks. But' I'm not swearing to nuttin' !!!

The HD C10 brakes are the same brakes that were used on all of them in the 70's. In the 80's, the thin rotors became the standard brakes. By that point, there was no Big 10 option.

 

[HotRodPC]

The HD C10 brakes are the same brakes that were used on all of them in the 70's. In the 80's, the thin rotors became the standard brakes. By that point, there was no Big 10 option.

I was aware of the thinner rotors in the 80's, but you're saying even the Big 10 and Heavy Half has the same brakes as the standard half tons? So then what is RPO Code J55 HD Brakes mean? Maybe rears wider shoes???

 

[f6john]

Mine does have the wide rear brakes too.

 

[bucket]

I was aware of the thinner rotors in the 80's, but you're saying even the Big 10 and Heavy Half has the same brakes as the standard half tons? So then what is RPO Code J55 HD Brakes mean? Maybe rears wider shoes???

Big 10 and Heavy Half were just regular half tons with slightly heavier springs and maybe just a couple other very minor details. But they don't have anything to do with the LD/HD brakes in the 80's.

 

[f6john]

I purchased new hoses for the the front brakes and boy is this going to be a job! The flair nut on the hard line is inside the C formed by the frame rail. I can barely get my hand in there to put the wrench on it and then I discovered I didn’t have the right size. I know I have one as I used it on my Impala last fall when I replaced all the flex lines on it. I spent more time looking for the wrench yesterday than working on the truck.

 

[Frankenchevy]

so are the jb7's the 1-1/2" thick rotors on the front?

 

[bucket]

so are the jb7's the 1-1/2" thick rotors on the front?

I don't recall what each of the codes were, but iirc, JB7 was the option for 3/4 ton trucks. But yeah, 1 1/4 thick rotors. The only thing that got 1 inch thick rotors was the standard C10 (LD) in the 80's. HD brakes on a C10 meant the thicker rotors, like was standard in the 70's.

 

[Frankenchevy]

I don't recall what each of the codes were, but iirc, JB7 was the option for 3/4 ton trucks. But yeah, 1 1/4 thick rotors. The only thing that got 1 inch thick rotors was the standard C10 (LD) in the 80's. HD brakes on a C10 meant the thicker rotors, like was standard in the 70's.

What do they call the 1-1/2” rotors...JB8?

 

[bucket]

What do they call the 1-1/2” rotors...JB8?

Dunno, that really wasn't an option. That was 1 ton stuff.

 

[Frankenchevy]

Dunno, that really wasn't an option. That was 1 ton stuff.

that's what I'm working with. I guess I'll need to remove my rotor and take it in. I'm starting to work on the front end in my truck and the rotor thickness is 1-1/2" they can't seem to pull up the right ones at auto zone or Napa. I also need to figure out which hub nut socket I need for my locking hubs to get the rotors off in the first place...