Dana 80 Axle Service

How to Replace the Fluid in a Dana 80 Rear Differential

The Dana 80 rear differential has been used in a number of Dodge, Ford, and GMC/Chevrolet truck applications beginning as far back as 1988. There's nothing small about the Dana 80, which features 4" axle tubes, 1-1/2" axle shafts, and an 11" ring gear. Fluid replacement intervals vary by manufacturer and in some instances are affected by the type/viscosity of the oil used; refer to your owners manual and follow the OEM's recommendations.

Applicable model years: Various Ford, Dodge, GMC/Chevrolet
Dana 80 differential cover gasket: Dana Spicer part # RD51997
Dana 80 fluid spec:
80W-90 or 75W-140, see specs below

Dana 80 Specifications

Manufacturer:

Dana Holding Corporation

Applications:

• 1994 - 2002 Dodge Ram 3500
• 1994 - 2002 Dodge Ram 2500, V-10 gas or 5.9L Cummins w/ manual transmission only
• 1988 - 1998 Ford F-350 DRW
• 1999 - 2016 Ford F-350 Super Duty DRW
• 1988 - 2004 Ford F-450 (F-Super Duty)
• Select 2011 - 2014 Ford F-450 Super Duty
• 1991 - 2002 Chevrolet/GMC C3500HD

Type:

Full floating rear differential

Ring Gear Diameter:

11.00"

Pinion Shaft Diameter:

2.00"

Pinion Shaft Spline:

37 spline

Axle Tube Diameter:

4.00"

Axle Shaft Diameter:

1.50" (35 spline), 1.58" (37 spline)

Axle Shaft Spline:

35 spline (1.50" axle shaft), 37 spline (1.58" axle shaft)

Max GAWR:

11,000 lbs

Gear Ratio Range:

3.23 : 1 to 5.38 : 1

Fluid Spec:

• Dodge - SAE 80W-90, 75W-140 suggested as a heavy duty alternative
• Ford - SAE 75W-140 full synthetic
• Chevrolet/GMC - SAE 80W-90, 75W-140 is suggested as an alternative to more frequent fluid changes per the C3500HD manual

Synthetic fluid is recommended in all instances

Fluid Capacity:

Ford calls for 4.2 quarts, Dodge calls for 3.4 or 5.0 quarts depending on the application - always fill differential until oil reaches the fill plug level. Limited slip differentials may require an additive, refer to owners manual.

 

Dana 80 Differential Fluid Change Procedures

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Dana 80 rear axle

• Place the transmission in park (automatic) or in gear (manual) and set the parking brake.

• The Cardinal rule - always make sure you can remove the fill plug before draining the differential and rendering the truck inoperable. Remove the fill plug using a 5/8" square drive socket. If it won't budge, consider your removal options before draining the oil.

• The Dana 80 differential cover is held in place by (10) bolts. Remove (8) of the bolts and generously loosen (but do not remove) the two top bolts such that the cover will be held in place while the fluid drains.

Draining the Dana 80 differential

• Use a flathead screwdriver, putty knife, or similar tool to break the seal between the differential housing. Be cautious as not to mar the machined surface of the differential housing.

• Allow the differential to drain completely, then remove the remaining cover bolts and then the entire differential housing cover.

Dana 80 with cover removed

• With the cover removed, use a lint free rag to completely remove any remaining fluid from the differential.

• Inspect the bottom of the differential housing for any metal particles/debris, which may indicate severe wear and/or damage.

Cleaning Dana 80 sealing surface

• Using a plastic bag to protect the inside of the differential housing from debris and contamination, thoroughly clean the differential housing of any remnant sealant and/or gasket material. Lightly spray a lint free rag with a solvent (brake cleaner, carb cleaner, etc) and clean the surface of any oil residue. Do not spray solvent directly on the housing or allow any inside the differential housing.

Dana 80 cover being cleaned

• Thoroughly clean the differential housing cover, removing any traces of previous gasket material and/or sealant. Remove any oil from the seating surface with a solvent (brake cleaner, carb cleaner, etc). Remove any debris from the inside of the cover once it has been cleaned.

• Clean the cover bolts of any sealant and oil.

Dana 80 gasket installed

• The Dana 80 differential does not require a gasket - you can use an oil resistant RTV silicon alone, or you can use a gasket and RTV silicon. This is somewhat a matter of preference and experience, but we've opted to install a gasket against the differential housing and use silicon to seal the cover. Whichever route you decide, lay a continuous bead of oil resistant RTV silicon around the entire mating surface of the housing (3/16" - 1/4" bead is sufficient) and around the bolt holes. You may also choose to place a dab of silicon on each of the cover mounting bolts.

Dana 80 fill port location

• Reinstall the differential housing cover. Snug all bolts in a star pattern, alternating from side-to-side. Finally, torque the cover bolts to 30 lb-ft in an alternating pattern.

• Allow the silicon to cure per the manufacturer's recommendations (24 hours is relatively common if no time interval is given).

• Remove the square drive fill plug and add fluid until it reaches the fill plug level and begins to run out of the cover. Replace the fill plug (torque to 25 lb-ft), test drive the vehicle, and check for leaks.