TOYOTA 90171-16009 Ball Joint Castle Nut

Genuine Toyota OEM castle nut, part number 90171-16009. This specialized fastener is designed for critical points in the vehicle's suspension and steering systems, specifically for securing ball joint studs.

Functional Description and Importance

The castle nut, also known as a castellated nut, features distinctive slots (a "crown") on one end. Its design is essential for vehicle safety. It is used in conjunction with a cotter pin (split pin), which is passed through the slots and a pre-drilled hole in the bolt or stud. This mechanical locking mechanism physically prevents the nut from loosening or unscrewing due to vibrations, road imperfections, and dynamic loads experienced during driving. For components like ball joints, which connect control arms to steering knuckles, maintaining proper torque and preventing loosening is crucial for safe and predictable vehicle handling.

Common Signs of Failure or Need for Replacement

Although the nut itself is a durable component, it should be inspected and replaced under certain circumstances. Replacement is recommended if:

• The threads of the nut are damaged or stripped.
• The hexagonal flats are rounded off due to improper tool use, making it impossible to tighten to the correct torque.
• Significant corrosion is present, which could compromise its structural integrity.
• The original nut is removed during a repair. It is a best practice, especially for critical safety components, to use a new fastener upon reassembly to ensure proper clamping force and a secure lock with a new cotter pin.

Technical Specifications

• Part Number: 90171-16009
• Brand: Toyota (Genuine OEM)
• Part Type: Castle Nut
• Material: High-tensile steel for strength and durability
• Surface Finish: Typically coated with a corrosion-resistant finish
• Application: Primarily for front and/or rear suspension ball joints

Vehicle Compatibility / Application

This part is a direct fit for the following models:

• Toyota Land Cruiser 200 (VDJ200)
• Toyota Land Cruiser 200 (UZJ200)
• Toyota Land Cruiser 200 (URJ200)
• Toyota Land Cruiser 200 (GRJ200)

Note: Always verify compatibility with your vehicle's chassis number (VIN) before purchasing.