CHASSIS-PARTS GLOSSARY
Tie Rod
Also called: track rod (UK/EU), steering tie rod, tie rod assembly. Its inner part is the rack end, also listed as inner tie rod or axial joint in European catalogues; its outer part is the tie rod end (track rod end).
What it is
A tie rod is the steering rod that connects the steering gear or center link to the steering knuckle at each front wheel, pushing and pulling the knuckle so the wheel turns. On rack-and-pinion steering each side has a tie rod in two parts: the inner tie rod (rack end), which screws onto the steering rack, and the outer tie rod end, which bolts to the knuckle; the threaded joint between them sets the wheel's toe. On a solid front axle a single tie rod (track rod) runs across the axle and links both knuckles.
How it works
Turning the wheel
When the rack or center link moves sideways, the tie rod pushes or pulls the steering arm on the knuckle. The knuckle pivots around its steering axis on the ball joints or kingpin, and the wheel turns.
Setting the toe
The tie rod's working length is adjustable by its threads. During wheel alignment the technician turns the inner rod in or out of the tie rod end, or rotates an adjusting sleeve on parallelogram and solid-axle rods, then locks the setting with a jam nut or clamps.
Following the suspension
Ball joints at both ends let the tie rod swing up and down with the suspension while it keeps steering. Correct geometry keeps the toe almost constant over bumps; a wrong tie rod angle causes bump steer.
Construction
A rack-and-pinion tie rod is a steel rod with a ball socket at the inner end (the rack end, sealed inside the rack bellows boot) and a threaded outer end that takes the tie rod end and a lock nut. Parallelogram and solid-axle tie rods are often built from an adjusting sleeve with left- and right-hand threads joining two tie rod ends, held by clamps. Bellows boots and dust boots keep water and grit out of the joints.
Common failure symptoms
- Loose or vague steering
- Play in the inner or outer joint lets the wheel move without steering input.
- Uneven tyre wear
- Toe that drifts while driving wears the inner or outer edge of the tyre.
- Clunk when turning or over bumps
- A worn ball socket knocks as the load on the rod changes direction.
- Bent rod after an impact
- The steering wheel sits off-centre or the vehicle pulls. A bent tie rod is replaced, not straightened.
- Torn rack bellows boot
- Water and grit reach the rack end and the rack itself, accelerating wear of both.
Frequently asked
What is the difference between a tie rod and a tie rod end?
The tie rod is the whole rod between the steering gear and the knuckle. The tie rod end is only its outer ball joint, bolted to the knuckle. On rack-and-pinion steering the tie rod end and the inner tie rod (rack end) are separate replacement parts.
Is an inner tie rod the same as a rack end?
Yes. Inner tie rod, rack end and axial joint are names for the same part: the rod with a ball socket that screws onto the end of the steering rack, under the bellows boot.
Is a tie rod the same as a track rod or a drag link?
Track rod is the UK name for a tie rod. A drag link is a different rod: it carries the steering input from the pitman arm, while the tie rod links the wheels so they turn together.
Should tie rods be replaced in pairs?
Not necessarily. Each side wears independently, so one worn side can be replaced on its own; on high-mileage vehicles many workshops replace both to keep the steering even. The toe must be set either way.
Do I need a wheel alignment after replacing a tie rod?
Yes. Replacing a tie rod or tie rod end changes the toe, so it must be measured and set, and the jam nut locked afterwards.
Can a bent tie rod be straightened?
It should be replaced. Straightening can leave hidden cracks in a safety-critical part, and a bent rod usually means its ball joints took the impact too.
Example OE numbers
- 53540-SMG-003 Honda
- 45046-09090 Toyota
- 48520-71L25 Nissan
- 48810-60J00 Suzuki
- 0K55232280 Kia
- 4422A002 Mitsubishi
External references
Independent technical sources (in English) for further reading. SLOOPZONE is not affiliated with these publishers.
- Steering Wikipedia
- Rack and pinion Wikipedia
- MOT inspection manual, 2. Steering GOV.UK