1. Worm Bearing Prelude Adjustment
2. Pitman Shaft Over Center Clearance
You must set the worm bearing pre-load first and over-center clearance second. 1. Worm Bearing Prelude Adjustment The adjustment assured that the worm shaft is held snugly inside the gearbox housing. If The Worm shaft bearings are too loose the worm shaft could move side ways and up and down during operation.
To make a worm bearing pre-load adjustment, disconnect the piston arm (if gearbox installed in the car). Losses the piston shaft over-center adjusting locknut and screw two turns. Then turn the steering wheel or worm shall (gear box out of car) from side to side slowly using a torque wrench measure the amount of force needed to turn the steering wheel worn shaft to the center position.
Note the reading on the torque wrench and compare your measurement to the specifications given by the vehicle manufacturer. If needed, loosen the worm adjuster lock nut. Then tighten the worm bearing adjuster to increase preload. Loosen it to decrease preload and turning effort.
Tighten the locknut and make sure the steering wheel or shaft turns freely from stop to stop. It is binds or feels rough and then the gearbox has damaged parts and should be rebuilt or replaced. After steering worm bearing preload adjust the pitman shaft over center cleanse. 2. Pitman Shaft Over Center Clearance Control the amount of play between pitman shaft (sector) ear and teeth on ball nut. It is the most critical adjustment effecting steering wheel play. To make the over center gearbox adjustment; find the center position of the steering wheel. Turn the steering or worm shaft from full right to full left while counting the number of turns. Divide the number of turns by two to find the middle. This will let you turn the steering wheel from full stop to the center.
The steering wheel or shaft must be centered during over-center adjustment. Most of the gearboxes are designed to have more gear tooth back lash (clearance) when turned to the right or left. A slightly preload is produced in the center position to avoid steering wheel play during straight ahead driving.
Loosen the screw locknut, turn the over center screw until it bottoms lightly. This will remove the backlash. Acting on the specific instructions in the service manual, measure the amount of force needed to turn the steering wheel or gearbox worm shaft. Loosen or tighten the pitman shaft screw as needed according to the specifications. Tighten the locknut and recheck gearbox action.
Power steering gearboxes sometimes require the adjustment of rack piston preload. Since procedures differ with the different vehicles. Always consult relevant shop manual of the vehicle under repair.