Different brake codes?

[Matt69olds]

Had to replace a brake hose on the 81 GMC. The truck makes a HARD left turn whenever you hit the brakes, and once you release the brakes it takes a couple seconds before the truck would start to roll. Obviously, the hose has collapsed internally.

Once I got it back together no matter what, I can’t get the hose on the passenger to stop leaking. I have the banjo bolt tight enough that I’m afraid it will snap if I go any tighter. My plan is to replace that caliper, I did kinda gouge the sealing surface picking off the copper washer.

My question: the parts store is asking if I have a JB1 or JB3 braking system. They can’t tell me the difference, this is a Frankenstein truck, and the RPO sticker is long gone.

It’s a 81 GMC 1/2 long bed 2wd, originally 350 Olds diesel powered. The factory Hydraboost system is long gone.

Can anyone in readerland tell me what I have, or tell me what to look for? Thanks.

 

[Ontheboulder]

Had to replace a brake hose on the 81 GMC. The truck makes a HARD left turn whenever you hit the brakes, and once you release the brakes it takes a couple seconds before the truck would start to roll. Obviously, the hose has collapsed internally.

Once I got it back together no matter what, I can’t get the hose on the passenger to stop leaking. I have the banjo bolt tight enough that I’m afraid it will snap if I go any tighter. My plan is to replace that caliper, I did kinda gouge the sealing surface picking off the copper washer.

My question: the parts store is asking if I have a JB1 or JB3 braking system. They can’t tell me the difference, this is a Frankenstein truck, and the RPO sticker is long gone.

It’s a 81 GMC 1/2 long bed 2wd, originally 350 Olds diesel powered. The factory Hydraboost system is long gone.

Can anyone in readerland tell me what I have, or tell me what to look for? Thanks.

it could be the threads if you replaced the bolt. check out the specs between jb1 and jb3 systems might be a difference in brake diameter which you can measure to find out. I had a wheel cylinder that had the wrong bleeder and the threads would not tighten up. todays junk parts!

 

[Matt69olds]

Same bolt, I used the new washers that came with the hose.

 

[rusted nuts]

Same bolt, I used the new washers that came with the hose.

Might be a bad hose.

 

[SquareRoot]

Maybe the attached will help. Sounds like JB3 would be fine. Regarding hoses, I always remove the bolt and hose with the banjo fitting and promptly toss em in the dumpster. Then I replace them with AN adapter fittings and -4 stainless braided lines. Soo much easier to work with and find replacement parts.

 

[Matt69olds]

Maybe the attached will help. Sounds like JB3 would be fine. Regarding hoses, I always remove the bolt and hose with the banjo fitting and promptly toss em in the dumpster. Then I replace them with AN adapter fittings and -4 stainless braided lines. Soo much easier to work with and find replacement parts.

Sounds like a pretty easy question to answer!! Power brakes or manual?

Now why couldn’t the counter help tell me that???

 

[Keith Seymore]

They are to busy trying to find out if it's a manual or automatic trans, and if it has a/c.

K

 

[Grit dog]

I was gonna say buy both and return one.
Woulda made that call at the parts counter so I could complete the repair as intended when intended.