Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Front Differential: Adjustment
- Using the ST, screw-in the differential side retainer until resistance is felt.NOTE: RH side should be screwed-in more than LH side.
Preparation tool:
ST: WRENCH COMPL RETAINER (18658AA021)
- Using the ST, install the drive pinion retainer.
Preparation tool:
ST: SOCKET (E20) (18270KA020)
Tightening torque:
43 N.m (4.4 kgf-m, 31.7 ft-lb)
- Rotate the drive pinion ten times or more using ST1 and ST2.
Preparation tool:
ST1: HOLDER (498937110)
ST2: WRENCH (499787700)
- While rotating the drive pinion, tighten the LH differential side retainer and loosen the RH side until it does not rotate anymore. The backlash is "zero" when the drive pinion comes to the point where it doesn't rotate.
- After reaching the "zero" state, loosen the LH differential side retainer by 3 notches and secure it with the lock plate. Retighten until the RH differential side retainer stops. Rotate the drive pinion 2 or 3 times. Tighten the RH differential side retainer further 1-3/4 notches. This sets the preload. Finally, secure the differential side retainer with the lock plate.NOTE: Turning the differential side retainer by one notch (A) changes the backlash approx. 0.05 mm (0.0020 in).
- Insert the ST (Axle Shaft) into the right and left sides of differential case.NOTE: The ST (Axle Shaft) is a SUBARU genuine part.
- Install the ST to the drive pinion retainer, and wrap the drive pinion with cloth and pinch with vise pliers. Using a tie-wrap or a wire, fix the vise pliers to the ST.NOTE: Make sure the drive pinion does not move.
Preparation tool:
ST: COMPRESSOR SHAFT (18763AA000)
- Check that the backlash of hypoid gear set is within specification using the ST, a dial gauge and a magnet stand.
Preparation tool:
ST: PLATE (498255400)
Specification:
0.13 - 0.18 mm (0.005 - 0.007 in)
- Adjust the tooth contact of hypoid gear set. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR580)>DRIVE PINION>ADJUSTMENT .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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