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 3.73-4.56 for reverse rotation.
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
Wrangler Dana 30
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.
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CJ Normal cut Dana 30
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YJ Reverse cut Dana 30
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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.
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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.
Comanche, Cherokee, and Grand Cherokee Dana 30
The Comanche (MJ) and Cherokee (XJ) use a reverse cut Dana 30 and
the Grand Cherokee (ZJ) uses a normal cut Dana 30. Like the YJ and
the TJ, these axles use a 5 on 4.5" wheel bolt pattern.
All of these trucks use coil springs up front.
FSJ
The Dana 30 front axle was used for a short time from 1971-1973 in
Cherokees (SJ), Wagoneers (SJ), and J-Series pickups.
Other Dana 30 Information
Here are some other articles related to the Dana 30.
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Dana 30 Disk Brake Conversion:
How to convert a drum brake Dana 30 to disk brakes. Some minor
Dana 30 differences are documented in this article including
differences in spindles, bearings, and brake hubs. This article
also explains why the Dana 30 is a good low buck axle upgrade
for '45-'71 CJs.
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Specifications
| Model/Version | Spring Pads | Wheel to Wheel | Years |
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| Dana 30/CJ Narrow Track | 28" | 53" | '72-'81 |
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| Dana 30/CJ Wide Track | 28" | 56" | '82-'86 |
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| Dana 30/XJ | NA | 60 3/4" | '84- |
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| Dana 30/MJ | NA | NA | '86-'92 |
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| Dana 30/YJ | 31" | 60" | '87-'95 |
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| Dana 30/ZJ | NA | NA | '93- |
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| Dana 30/TJ | NA | NA | '97- |
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Contributors
Thanks to Joe Schaefer for the FSJ Dana 30 dates.
