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The Dana/Spicer Model 44 is an automotive axle manufactured by Dana Corp. and is used extensively among automobile manufacturers and in the automotive aftermarket area as well. The Dana 44 was first manufactured in the 1940s and is still being manufactured today, both front and rear axle variants. The Dana 44 has been manufactured as a beam axle and independent suspension for both front and rear axle setups. There are also different variations of the Dana 44. Over a dozen automobile manufacturers have made vehicles that feature Dana 44 axles, including Jeep which currently manufactures Four-wheel drive vehicles that feature both front and rear Dana 44 axles.
On some differentials only the high speed 2.72–3.73 carrier is used for all gear sets up to 5.89 (JK, Nissan or when thick gears are used)
The Dana 44 Front axle first saw use in the 1950s and still in use today. Dana 44 Front axles were known for utilizing locking hubs or a center axle disconnect system. However, a permanently locked-in Dana 44 is not uncommon. The Dana 44 has seen use in 1/4-, 1/2-, 3/4-, and 1-ton rated trucks. The Dana 44 was manufactured in kingpin and ball joint variations, as well as closed and open knuckle variations.
In the 1960s, Jeep used a unique Dana 44 IFS setup, that was short lived. In the 1980s and 1990s, Ford used a form of IFS known as "Twin Traction Beam" (TTB). This Dana 44 had no axle tubes but attached to the driver side traction beam, which also acted as a cover plate, and had "open air" axles which traveled through the beams to the spindles. The axles had u-joints to allow for the independent action of the beams. Individual pivot points for the beams at greater than center made each beam longer than half the overall width crossing in the middle. This allowed for an independent front suspension design. Ford TTB Dana 44 axles all utilized locking hubs. The TTB set-up is based on Ford's highly successful Twin I-beam design on two-wheel-drive pick-up truck models.
The Dana 41 was the precursor to the Dana 44 and was used from the 1930s to the 1950s. The ring gear on the Dana 41 is near one inch smaller than a Dana 44.
The Dana 44 rear axle first saw use in the 1940s and is still in use today. The Dana 44 has a GAWR up to 3,500 lb (1,600 kg) and is a semi-floating type, having one bearing on the end of the axle shaft which carries the weight of the vehicle on the axle and also allows axle rotation.
There is a 8.9" diameter Dana 44 ring and pinion that is very different from the standard Dana 44. This ring and pinion is significantly stronger with a better pinion to ring gear tooth contact patch and angle. It was typically used in the back of jeep JKs, Isuzus and Nissan pickups. This ring and pinion does share some components and can be adapted into an earlier Dana 44 but requires some work, different bearings and spacers. The benefit is the larger ring gear, better angle cut on the teeth and Dana 60 diameter pinion shaft.
The Dana Spicer Max momentary output torque FT-lbs
The Dana 45 was introduced during the 1950s as an upgraded Dana 44 with larger 20 spline axle shafts. Since the Dana 45 is no longer being made you can use the Dana 44 gears in the Dana 45 housing if you use model 53 pinion bearings and lots of shims.
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The Dana 44 has seen use in Chevrolet Corvettes and Dodge Vipers. This axle is referred to as a Dana 44 ICA or Dana 44 IRS. Some 1985–1996 Chevrolet Corvette C4 featured this axle. A rear transaxle was used starting with the Corvette C5. The 2005–06 Pontiac GTO, The Dodge Viper has always used a Dana 44 IRS setup. The majority of Corvette and Viper Dana 44 IRS set ups use a limited slip differential.
Jaguar first used the Dana 44 in an IRS in 1961 for the Jaguar E-type as well as other models. It was used through 1996 (Jaguar IRS Article). There are some differences in the Jaguar Dana 44, however. The differential (possibly the entire axle assembly) was made by Salisbury, a U.K. division of Dana Corporation. The ring gear in the Salisbury version uses slightly smaller mounting bolts and the pinion shaft is a different diameter than the common version. Naturally the cast housing is also unique to the IRS model. Standard 8.5" Dana 44 ring and pinion gear can be used in the IRS model through the use of a special installation kit which includes special shouldered bolts to mount the standard ring gear to the IRS carrier and a special pinion bearing set to fit the standard pinion shaft to the IRS housing. Gear distributors with knowledge of the Jag IRS should be able to get the installation kit. US Dana 44 gears a slightly stronger than Jaguar gears, and Jaguar gears higher priced, but once the installation kit price is added to the lower US gear prices cost is about the same. If Jaguar makes the needed gear ratio there isn't much difference in strength. The consensus in the hot rodding community is that the Jaguar IRS is good for up to 500 hp from the factory. Most V-12 Jaguar and E-type six-cylinder models used limited slip versions, other models (mainly the XJS) used a standard differential stock with limited slip as an option.
A Dana 36 IRS was used in all Corvettes in 1984 and automatic transmission equipped Corvettes from 1985 to 1996. The Dana 36 has a ring gear diameter of 7.75 inches (197 mm), and has gear ratios ranging from 2.53:1 to 3.31:1.
Independent Rear Suspension (IRS)
Note: there was a change in design of the Jaguar IRS after 1985. The 61–84 unit is in a stamped steel "cage" that is self-contained and easily removed as a single unit (see photo in this article). This makes it relatively easy to adapt to other vehicles. The 1986 and later unit uses a subframe/lower wishbone design that is not easily adaptable to other vehicles.