CJ Dana 30s
Early Dana 30s used a 11"x2" drum brake. Disk brakes were optional in 1976 and standard starting in 1977. Between '76-'78 the disk brakes used a large 10-1/2"x1-1/8" rotor. The "big brake" setup uses a 6 bolt caliper mounting bracket that goes between the knuckle and the spindle. The caliper is keyed to the mouting bracket and the rotor should apear wide when looking on edge. Rubber brake hoses with brass banjo fitting end. These rotors, calipers, and pads are compatible with the Scout II.
From 1979-1986 they used a 10-1/2"x7/8" rotor with a 2 bolt to knuckle caliper mounting bracket. From '79-'81 the caliper is keyed to the mounting bracket and uses rubber brake hoses with brass banjo fitting end. From '82-'86 the caliper is pin-bolted to the caliper bracket and the hoses are rubber crimped to steel line. All Dana 30s from 1972-1980 use a six bolt locking hub. From '72-'78 the factory had Warn Premium hubs as an option. From '79-'80 the factory used Warn non-premium hubs stock. From 1981-1986 they use a weak Warn five bolt locking hub stock. Jeeps built in the 70s with the Quadratrac transfer case will not have hubs at all unless they have been converted to part-time operation. They have driven plates instead. Hubs should not be used with this transfer case unless it has been converted to part-time operation.
Another big difference between the CJ and Dana 30s used in later models is the CJ has the diff case offset on the passenger side and the later models have the diff case offset on the drivers side.
Most CJ Dana 30s will have lock-outs on the hubs to engage or disengage the wheel from the axle. With both hubs unlocked, the axles, u-joints, differential, and front drive shaft do not spin. This is done to increase gas milage, and if a locker is installed in the front diff, it will impove handling on the pavement. Later model Dana 30s either an axle disconnect system or no disconnect system.
The CJ Dana 30 uses the 5 on 5.5" wheel bolt pattern other models use the 5 on 4.5" wheel bolt pattern.
Outer parts (knuckles out) can be switched amoung to different versions of the CJ Dana 30. This means CJs with drum brakes can upgrade to disk and CJs with cheesy 5 bolt locking hubs can upgrade to 6 bolt locking hubs. Later models use different knuckles and ball joints that are not compatible to the CJ Dana 30. Common gear ratios from '72-'75 were 3.73, from '76-'79 were 3.54, and from '80-'86 were 2.73
This is from jeep tech.com