Steering rack knock: causes, steering play and heavy steering

A knock felt through the steering wheel over bumps, play in the wheel, or steering that has become heavy or sticky are signs of a steering fault. The cause may be the steering rack itself, or the tie rods, tie rod ends or steering shaft joint, so we check the rack together with the suspension. Steering directly affects how the car handles, so these symptoms shouldn’t be put off.

How it shows up

• A dull knock in the steering wheel over small bumps and cobblestones
• Free play in the steering wheel, the car wanders on the road
• Steering has become heavy, especially at low speed or when cold
• The steering sticks or doesn’t self-centre after a turn
• Power steering fluid leaks, the pump whines when turning
• The electric power steering warning light is on

Possible causes

1. 01

   Worn rack bushings and yoke

   The support bushing and rack yoke (thrust pad) wear over time, and the rack starts knocking over bumps. On many racks this is fixed by a repair without replacing the unit.

2. 02

   Worn pinion and rack teeth

   Gear wear causes play and knocking, often uneven across the steering range. The degree of wear determines whether repairing the rack makes sense.

3. 03

   Tie rods and tie rod ends

   Play in tie rod joints feels very similar to a rack knock and comes through the wheel. We check these first because they’re simpler and cheaper to replace.

4. 04

   Steering shaft universal joint

   A worn intermediate shaft joint causes knocking and clicking in the wheel as well as noticeable play. It’s often mistaken for a rack fault.

5. 05

   Hydraulic power steering: seals, pump, fluid

   Worn rack seals cause leaks and heavy steering; a worn pump causes whining and uneven effort. Low or old fluid speeds up wear.

6. 06

   Electric power steering

   A faulty sensor, motor or wiring causes heavy or jerky steering and a warning light. This also requires checking the electrical side.

How we check

1. 01We ask exactly when the steering knocks or gets heavy and, if needed, take a test drive
2. 02On a lift we check the rack, tie rods, tie rod ends and steering shaft joint for play
3. 03We inspect the boots, look for leaks and check power steering fluid level and condition
4. 04We explain what’s faulty and agree on a rack repair or parts replacement before starting work