8-94429499-1 Power Steering Gear Box Fit 8944294991 ISUZU NHR55 / NKR55 / NKP J116

Product Function Description

The power steering gear box (part number 8-94429499-1) is a critical component of your Isuzu or JMC light truck‘s steering system. Its primary function is to convert the rotational motion of the steering wheel into the lateral movement needed to turn the front wheels. This mechanical steering gear box is designed for left-hand drive (LHD) applications and is suitable for Isuzu NHR, NKR, and JMC J116 models. A properly functioning steering gear box is essential for precise steering control, stable handling, and safe vehicle operation.

 Product Attributes

Core Vehicle Fitment: Isuzu NHR55 / NKR55 / NKP series light trucks (typically older-generation 1-ton to 2.8-ton trucks and box vans).

8-97006-564-0 (a related optimized/upgraded part number used by Isuzu on later NHR/1-ton mechanical steering gear assemblies).

Component Location & Core Function

Location: The power steering gear box is mounted on the vehicle’s frame rail on the driver’s side (left-hand drive). It sits between the steering column (input) and the steering linkage (output), connecting to the pitman arm on the output shaft.

Connections: The input shaft connects to the steering column via a steering coupling or universal joint. The output shaft connects to the pitman arm, which links to the steering drag link and tie rod assembly. Hydraulic lines (if equipped with power assist) connect to the gear box housing. The gear box is secured to the frame with mounting bolts through the bracket.

Core Function: The steering gear box serves as the primary conversion mechanism in the steering system, translating the driver’s steering input into controlled lateral force at the front wheels. It provides the gear reduction necessary to multiply steering effort and enable precise directional control.

Why Choose This Steering Gear Box?

Direct Replacement – Precision-engineered to match the original steering gear box specifications for Isuzu NHR, NKR, and JMC J116 applications.

Left-Hand Drive Configuration – Designed specifically for LHD vehicles, ensuring correct fitment and steering operation.

Mechanical Steering Design – Provides reliable, consistent steering performance for light truck applications.

Installation Tips & Common Mistakes

The Mistake When Replacing a Power Steering Gear Box:

❌ Wrong: Failing to bleed the power steering system or not checking for leaks after installation.

✅ Correct:

1. Always bleed the power steering system – Air in the system causes noise, hard steering, and pump damage.

2. Use a pitman arm puller – Hammering damages the pitman arm and steering linkage.

3. Check for leaks – After starting the engine, inspect all connections for fluid leaks.

4. Use the correct fluid – Use the power steering fluid specified for your vehicle.

5. Check steering operation – Test the steering at low speed before road driving.

⚠️ Remember: A power steering system that is not properly bled will cause pump damage and steering difficulty. Always bleed the system thoroughly after installation.

Package Contents

• 1 × Power Steering Gear Box

• Protective packaging with part number label

Note: Mounting hardware and power steering fluid are not included. Confirm with your specific seller.

Inspection & Maintenance Recommendations

The power steering gear box should be inspected during routine maintenance. Signs of steering play, leaks, or hard steering indicate the need for inspection or replacement.

Common indicators that the gear box may need replacement:

Inspection Checklist:

• Check power steering fluid level and condition.

• Inspect gear box and hydraulic lines for leaks.

• Check steering play by turning the steering wheel.

• Listen for unusual noises during steering.

Maintenance Tips:

• Check power steering fluid level regularly.

• Inspect for leaks at the gear box and hydraulic lines.

• Bleed the system after any steering component replacement.

• Use the correct power steering fluid.

After Replacement Still Having Issues?

Replaced the steering gear box but still having issues? Check these:

1. Was the system bled properly? – Air in the system causes noise and hard steering

2. Is the power steering pump working? – A failing pump affects steering assist

3. Are the hydraulic lines tight? – Loose connections cause leaks and air entry

4. Is the pitman arm installed correctly? – Incorrect installation affects steering geometry

5. Is the steering column connected properly? – Loose connection causes steering play

6. Is the fluid level correct? – Low fluid causes hard steering and pump damage

7. Is the steering linkage worn? – Worn tie rods or drag link affect steering response

Quality Assurance & Service Commitment

Quality Assurance:
Every component is manufactured under controlled production processes to ensure consistent dimensional accuracy and material integrity. Each unit undergoes the following quality checks before packaging:

• Dimensional inspection – critical mounting points and shaft dimensions are verified against design specifications

• Hydraulic test – internal sealing and pressure integrity are confirmed

• Steering operation test – smooth operation and proper response are verified

• Surface finish inspection – surface quality is visually verified

Packaging Protection:
Each steering gear box is individually sealed in protective packaging to prevent contamination and physical damage during storage and transit. The packaging includes a clear part number label for easy identification.

Service Commitment:

Related Product Recommendations 

When replacing the power steering gear box, it is often recommended to inspect and consider replacing the following related components at the same time.