Steering box Wear Signs
Most older cars use a recirculating-ball or worm-and-sector steering unit, rather than a rack-and-pinion steering set. These units have their own particular wearing points.
Free Play Before the Wheels Respond
Test for free play before the wheels start to track. This test is carried out by slowly turning the steering wheel from side to side. A small amount of free play is acceptable but if there is too much, the gears in the steering box will continue to wear until eventually excessive wear will occur and require a complete overhaul. This wear can occur over a long period of time and may not seem to cause any immediate problems.
Clunking Through the Wheel on Bumps
A worn steering box can produce a knocking or clunking sound that is felt through the steering wheel. This symptom is most noticeable when driving slowly and going over rough ground. The knocking or clunking is usually caused by worn ball bearings in the recirculating balls or excessive clearance between the worm and sector shaft. The adjuster should be checked for correct preload and any wear on the internal gears.
Fluid Seeping From the Casing
Power-assisted steering units rely on hydraulic fluid to transfer force from the steering column to the wheels. The shaft seal on a worn or damaged steering box can leak fluid around the sector shaft or along the casing joint. A wet patch or sticky film on the underside of the box could indicate a leak from the shaft seal. This should be repaired before the fluid level falls too much and results in increased resistance when steering.
Tight or Notchy Feel on Centre
A stiff or notchy feeling when the wheel is returned to the straight ahead position can be due to the steering box adjuster having been over-tightened in an attempt to compensate for wear. Alternatively, the worm gear within the steering box could be pitted, again resulting in uneven resistance when driving, which will cause tiredness on long motorway journeys.
What to Look for on the Unit Itself
Inspect the box casing, the mounts and the drop-arm connected to the sector shaft. Any cracks in the mounts, corrosion on the casing or any side play in the drop-arm are serious problems and must be addressed as soon as possible.
Identifying these symptoms early can save you a lot of time and money as it’s possible to refurbish a worn steering box, but a complete failure can mean that it’s time to look for a new one.