TowRig.com - Diesel Discussion and Tow Tech

I have an '85 C30 dually with the 6.2, sm465, and a 4.10 Dana 70 rear in it. I went to get rear brakes for it tonight and they asked if it was a JB7 or JB8 brake system. Went and looked in the door jams and in the glove box for some sort of code to tell me which it is and there was no code of the sort in either place that I could see :mad: . Anyone happen to know how to tell the difference before I rip this thing apart?????

It might have something to do with the rear axle. I see yours is a D70 but I think that they ran the 14bff in those duallys as well...but I could be wrong

JD7 is in the C25 and the JD8 is in the C30.............From what I'm told. Single vs Dual wheel.

I was told it has to do with it being Hydroboost or not and brake shoe size. I am going to take it apart first and take the shoes with me when I go to get brakes.

I know that this probley wont help but my 88 r30 crew cab has the jb8 brake option.
thanks
Eldogg

JB8 brakes use 13x3.5" drums, and 1.5" thick rotors w/Bendix calipers.

I haven't seen any 1-tons since the mid 70's that used the JB7 (normally 3/4-ton) brake system.

It was a JB8. Put in new springs, shoes, driver's side wheel cylinder and adjuster (put these 2 parts in the passenger side last summer), and new seals in the back of the drums. Brakes are adjusted up and it stops like a champ now!!!waytogo Thanks for all the help.