whats these rpo codes

[blazin_blazer]

lookin at buyin new rotors & calipers for my rear disk conversion, i have diy's brackets & the rotors all seem to be the same, but calipers are showin 2 types w/these codes JB6, JD6 or JB7, JD7...will either work? is there any pro/con from 1 or the other? the 7's have a bigger piston or whats the difference?

 

[dyeager535]

Couple days old, but I'll BTT this for you. I've got my parts book at home, not sure it actually explains the difference between the two RPO's. It may show the exploded parts though.

 

[76zimmer]

JB6-Pwr disc/drum 7200gvw
JB7-Pwr disc/drum 8400gvw
JD6-Hyd. Pwr disc/drum 7200gvw
JD7-Hyd. Pwr disc/drum 8400gvw

 

[dyeager535]

But he needs to know what the specific differences are...JD6/7 would be hydroboost I assume, but JB6/7, the physical difference is?

If the mounting and brake line fittings are the same, probably not going to matter, but if there are other differences, then it could cause problems.

The parts manual should show if the backing plate is different, if it is, that would mean mounting is different. I can check my '85-88 parts manual tonight.

 

[76zimmer]

Yeh, all I got is the RPO description.

 

[bronc3buster842001]

The mounting is the same. The differance is in the size of the piston. I run the JB7 calipers up front and the JB6 in the back for my 4 wheel disk. It works good.

 

[dyeager535]

No argument there.

Parts manual shows the same backing plate on the 10 bolt fronts regardless of brake option. Brake caliper in general appears to be similar with either brake option, but the calipers themselves carry different PN's based on the brake code.