This Dana 30 features an open knuckle design with 7 1/5" ring gear.
Although the same model axle has been used for almost 25 years, they
are not compatible. There are numerous various in brakes, hubs,
differential orientation, wheel bolt pattern, and width.
The R&P ratio ranges supported by the carriers are 2.72-3.54 and
3.73-5.38 for the standard rotation and 2.73-3.54 and 3.73-4.88 for
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
The YJ and the TJ don't use locking hubs. The YJ uses a troublesome
vacuum actuated axle disconnect system. The TJ uses high quality
bearings that have very low resistence so it doesn't use hubs or an
axle disconnect system. Wranglers use and smaller rotor than the CJ.
The TJ also uses a different pinion from the YJ. The TJ pinion uses a
crush sleeve instead of shims. This difference made gear R&P selection
for the TJ a bit limited at first.
A strength of the YJ Dana 30 is its use of reverse cut ring and
pinion. The ring and pinion are stronger when they are reverse cut in
front axles. The reverse cut axle also provides better ground
clearance and driveline angles.
Unfortunately, the TJ does not use the reverse cut Dana 30. It uses
a normal cut Dana 30 similar, but not compatible to, the CJ Dana 30.
The YJ Dana 30 uses an axle disconnect system that is prone to
failure. Often the vacuum hoses the activate the disconnect system
will fall off or tear. Sometimes the vacuum motor won't have enough
power to engage the sleeve when the gear lube in the disconnect
housing gets gummed up. Another problem is that since only one axle is
ever disconnected, an automatic locker or limited slip differential
can cause problems with the axle and with handling. The drivers side
axle is always spinning the differential.
The TJ has done away with with the system completely which is good
in that it is not likely to fail, but since there is no way to stop
the differential from spinning, an automatic locker or limited slimp
can degrade handling on the road.
The YJ and the TJ Dana 30 uses the 5 on 4.5" wheel bolt pattern.
The YJ Dana 30 is of course set up for leaf springs and the TJ Dana 30
is set up for coil springs.
The Comanche (MJ), Cherokee (XJ), and the Grand Cherokee (ZJ and WJ)
use a reverse cut Dana 30. In the later years the Dana 30 was changed
to a low-pinion standard cut like the TJ. All these axles use a 5 on
4.5" wheel bolt pattern and are set up for coil springs.
The Dana 30 front axle was used for a short time from 1971-1973 in
Cherokees (SJ), Wagoneers (SJ), and J-Series pickups.
||Wheel to Wheel
|Dana 30/CJ Narrow Track
|Dana 30/CJ Wide Track
30 front axle. Photo courtesy Rick Boiros
Dana 30 front axle from a CJ with a regular cut housing
Dana 30 front axle reverse cut from Wrangler YJ.
Dana 30 front axle CJ spindles. The top spindle is a later CJ
spindle and the lower one is earlier. The outside diameter of the
bearings is the same with the later and earlier spindles, but the
inside diameter varies.
Dana 30 front axle vacuum disconnect from Wrangler YJ. The bracket
in the middle seems to be a track bar extension which was probably
part of some lift kit.
Dana 30 front axle
Dana 30 front axle from Wrangler YJ