AAM 9.25 IFS Front Differential

AAM 9.25 IFS Axle/Differential Specs, 1988+ Chevy/GMC 3/4, 1 ton Trucks

GM began employing the AAM 9.25 IFS in 1988, phasing out the long lived solid front axle in favor of improved ride quality and maneuverability. The axle differs from the 9.25 solid front differential used by Dodge in Ram 2500/3500 applications. The 9.25 utilizes a light weight cast aluminum differential housing and features 33 spline axle shafts. A variety of OEM gear options have been available, ranging from 3.42 - 4.56 to 1 ratios.

General Motors began phasing out solid front axles in favor of independent front suspension (IFS) systems in the late 1980's. GM's use of IFS, particularly in 3/4 and 1 ton trucks, has been a source of controversy in certain circles. While IFS offers superior ride quality and improved maneuverability, it is widely accepted that a comparable solid axle is significantly stronger and more reliable. Although "stronger" is a relative term, IFS systems require a more complex steering and suspension geometry that is more susceptible to wear and, in theory, there are many more possible points of failure than in a solid front axle system. In reality, the AAM 9.25 is more than adequate for its intended application and the average driver whom occasionally ventures off-road or requires 4 wheel drive infrequently will never observe the systems limitations. However, the axle's inherent weaknesses are quickly realized with aftermarket modifications that alter suspension geometry or increase engine performance when these trucks are used in motorsport applications or frequent, strenuous off-road use.

From 1988 to 2010, the AAM 9.25 was a clamshell type differential where the housing is assembled in two large halves (so to speak) and must be physically disassembled and split in order to access the components inside. The design changed to a standard Salisbury type differential housing in 2011, in which a typical (removable) cover offers access to inside the diff housing.

AAM 9.25 IFS Differential Specs

Manufacturer:

American Axle & Manufacturing (AAM)

Years Produced:

1988 - current

Applications:

1988 - 2000 Chevrolet/GMC K20 (K2500), K30 (K3500)
1988 - 2010 Chevrolet Suburban
2001 - 2019 Chevrolet Silverado 2500HD, 3500HD
2001 - 2019 GMC Sierra 2500HD, 3500HD
2000 - 2019 GMC Sierra Denali
1992 - 2019 GMC Yukon 2500
2000 - 2019 GMC Yukon XL 2500
2002 - 2006 Chevrolet Avalanche 2500
2004 - 2010 Chevrolet Express 3500
2002 - 2009 Hummer H2

Housing Material:

Cast aluminum

Housing Type:

Clamshell type through 2010 model year, Salisbury type (removable diff cover) 2011+

Differential Type:

Open, reverse cut ring & pinion

GAWR:

5,600 lbs (GM rating, Silverado/Sierra models)

Ring Gear Diameter:

9.25 in

Axle Spline Count:

33 spline

Factory Ratios:

1988 - 2010:

3.42 : 1, 3.73 : 1, 4.10 : 1, 4.56 : 1

2011+

3.42 : 1, 3.73 : 1, 4.10 : 1

Carrier Breaks:

None

Drain Plug Torque:

1988 - 2010:

24 ft-lbs (33 Nm)

2011+

18 - 30 ft-lbs (25 - 40 Nm)

Fill Plug Torque:

1988 - 2010:

24 ft-lbs (33 Nm)

2011+

18 - 30 ft-lbs (25 - 40 Nm)

Differential Cover Bolt Torque[1]:

24 - 34 ft-lbs (32 - 46 Nm)

Differential Cover Gasket[1]:

ACDelco 20768579

Lube Oil Spec[2]:

1988 - 2000, 2011+:

75W-90 (GM & AAM spec)

2001 - 2010:

80W-90 (GM spec)

Lube Oil Capacity[3]:

1988 - 2010:

1.82 U.S. qts

2011+

1.88 U.S. qts

Identification:

1988 - 2010:

clamshell

2011+

Salisbury, std diff cover

[1] Applies to Salisbury type differential only, 2011+ model year vehicles
[2] GM owners manuals varies between 75W-90 and 80W-90 spec; AAM data specs 75W-90 independent of application year. Either gear oil will suffice; full synthetic recommended by not required by manufacturer. Recommend Amsoil Severe Gear.
[3] Oil Capacity is nominal - always fill to bottom of fill plug with vehicle parked on level ground

Source(s)
American Axle & Manufacturing
General Motors; various owners manuals