Rear Drive Shaft Shim Selection

WARNING: This page is about a different variant/trim than selected.

Insert the rear drive shaft into the reduction drive gear and center differential assembly.

Fig 1: Identifying Reduction Drive Gear And Center Differential Assembly
Courtesy of SUBARU OF AMERICA, INC.
Using the ST, measure the depth "A", which is from mating surface of extension case to ball bearing outer ring contact surface.
ST 398643600 GAUGE

Fig 2: Measuring Depth From Mating Surface Of Extension Case To Ball Bearing Outer Ring Contact Surface
Courtesy of SUBARU OF AMERICA, INC.
Using the ST, measure the height "B" from the AT main case mating surface to the ball bearing outer ring contact surface.
ST 398643600 GAUGE

Fig 3: Measuring Height From AT Main Case Mating Surface To Ball Bearing Outer Ring Contact Surface
Courtesy of SUBARU OF AMERICA, INC.
Calculation formula:
When clearances are 0.05 mm (0.0020 in):

T (mm) = A - B + 0.23

[T (in) = A - B + 0.0091]

When clearances are 0.25 mm (0.0098 in):

T (mm) = A - B + 0.03

[T (in) = A - B + 0.0012]

A: Depth from end of extension case to ball bearing outer ring contact surface

B: Height from end of AT main case contact surface to the ball bearing outer ring contact surface

T: Shim thickness

Specification:

0.05 - 0.25 mm (0.0020 - 0.0098 in)

NOTE: Calculation formula for "T" above is applied when measuring with the ST (398643600 GAUGE).

When not using the ST,

When clearances are 0.05 mm (0.0020 in):

T (mm) = (A - α) - ((B - β) - 0.28) - 0.05

[T (in) = (A - α) - ((B - β) - 0.011) - 0.0020]

When clearances are 0.25 mm (0.0098 in):

T (mm) = (A - α) - ((B - β) - 0.28) - 0.25

[T (in) = (A - α) - ((B - β) - 0.011) - 0.0098] is applied.

T: Shim thickness

A: Depth from end of extension case to ball bearing outer ring contact surface

B: Height from end of AT main case contact surface to the ball bearing outer ring contact surface

α: Thickness of collar used when measuring "A"

β: Thickness of collar used when measuring "B"

0.28 (0.011): Gasket thickness (Unit mm (in))

Select the rear drive shaft shim so that the clearance is within the specified range.

Rear drive shaft shim
Part No.	Thickness mm (in)
33281AA040	0.2 (0.008)
33281AA050	0.5 (0.020)
33281AA060	0.3 (0.012)