What size bolt is a Subaru rear wheel bearing?
There is no single universal bolt size for Subaru rear wheel bearings—the bolt size varies by model and year. In practice, hub-to-knuckle mounting bolts are commonly in the 8–12 mm diameter range (roughly M8 to M12) with different thread pitches. Always verify the exact specification using your vehicle’s service manual or OEM parts diagram for your specific model.
Why bolt size varies across Subaru models
Subaru has used multiple hub and knuckle designs over its generations. The rear wheel bearing is typically part of a hub assembly that bolts to the rear suspension knuckle, and some models also rely on a center axle nut in addition to the outer mounting bolts. Because the hardware is model- and year-specific, the exact bolt size, thread pitch, and length are listed in official diagrams and service manuals. Using the wrong fasteners can affect wheel alignment, safety, and bearing seating, so it’s important to confirm the correct hardware for your exact vehicle.
Common sizes you might encounter
The following sizes are sometimes seen on various Subaru rear hub assemblies across different generations. This list is for reference only; always verify with the manual or parts diagram for your car.
- 8 mm diameter bolts (often M8 family) with common pitches such as 1.25
- 10 mm diameter bolts (M10 family) with pitches around 1.25–1.5
- 12 mm diameter bolts (M12 family) with pitches around 1.25
Actual hardware on your vehicle may be one of these or a different configuration. Always confirm with the exact specification for your model.
How to verify the exact bolt size for your Subaru
To determine the precise bolt size for your specific model and year, follow these steps:
- Check the owner’s manual or a factory service manual for your model/year, which lists hardware specifications for the rear hub.
- Inspect the existing bolts: measure diameter with calipers and count the thread pitch to identify whether you have an M8, M10, or M12 bolt and the exact pitch.
- Consult Subaru parts diagrams or catalogs for your VIN. Official diagrams show the bolt size and part number for the rear hub assembly.
- If you’re unsure, contact a Subaru dealer or a certified mechanic to confirm before removing or replacing the bearing hardware.
Verifying the exact hardware ensures you use the correct fasteners, preserving proper fit, torque, and safety on the road.
Installation notes and safety considerations
When replacing a rear wheel bearing or hub assembly, always use the exact OEM bolts or high-quality equivalents rated for Subaru wheel assemblies. Do not substitute with incorrect length, grade, or pitch. Re-torque to the specification after installation and re-check torque after a short drive as recommended by the service manual.
Summary
Because bolt sizes for Subaru rear wheel bearings vary by model and year, there is no one-size-fits-all answer. Commonly encountered diameters are in the 8–12 mm range, but the precise size, pitch, and length depend on your specific vehicle. Always verify with the official service manual, VIN-specific parts diagrams, or a dealership to ensure correct hardware and safe installation.
