What it Does
Steering rack boots/bellows are used to protect the inner steering tie rod joints and the steering rack ends and shafts from road debris and water splash. The boots are made from flexible plastic or rubber, which allows them to flex in and out as the steering rack pushes and pulls on both sides of the steering linkage to steer the vehicle.
Why This Matters
The rack boot is a protective component. This means that boot failure can result in the failure of the components that it’s supposed to protect. In this case, the protected components (inner tie rod and steering rack) are both steering system components. Failure of either of these components will cause a safety concern.
Possible Problems and Concerns
Torn Boot
Early Stage:
A small tear in the boot, if caught early, probably has not allowed much debris intrusion yet. The odds are good that debris intrusion has not yet caused the inner tie rod steering joint to wear. It’s also unlikely that any significant debris has intruded onto the rack shaft or accumulated in the rack end. Proactive boot replacement has a good shot at preventing a more costly failure.
Later Stage:
The longer a torn boot remains in service, and the larger the tear in the boot, the greater the odds of inner tie rod joint failure or steering rack trouble.
Loose Inner Tie Rod
Debris and water can intrude into the inner tie rod steering joints through a torn rack boot. This can result in debris loading of the joint and lubricant wash-out. Inner tie rods are steering linkage components. The steering rack pushes and pulls on these joints to steer the wheels. Loose tie rod joints can affect the vehicle’s stability, steering responsiveness, and alignment. A severely stressed or worn tie rod joint may separate completely, which is a very dangerous scenario (this results in complete loss of steering control for one wheel).
Steering Rack Leakage
Debris will intrude through a torn rack boot. If debris finds its way onto the steering rack shaft, it may get pulled back into the rack and jammed into the shaft seal. For example, a tight left turn will result in the rack shaft extending out on the right hand side of the rack. This could expose part of the shaft to debris. When the wheels are then turned back the other way, this shaft, now carrying debris, retracts back into the rack and toward the shaft seal. If the shaft seal is torn by debris, this will result in power steering fluid leaking from the rack.
Recommended Parts Brands
OE grade
Repair Notes
Generally speaking, the inner tie rod joint should be checked for play before boot replacement is performed. This helps account for the possibility of debris intrusion or lube wash-out resulting in wear, and sometimes these joints wear out anyway even if the rack boot is intact. Joint replacement will require rack boot removal anyway so we don’t want to go installing a new boot over a worn joint.