Rear Brake Wheel Cylinder 8-97358878-0 8973588780 For ISUZU NPR NQR NRR ELF 4HK1 4JJ1 — OEM Verified Direct Fit, 1-5/16" Bore Cast Iron, Rear Left With Auto Adjuster

The Rear Left Brake Wheel Cylinder with OEM numbers 8-97358878-0 / 8973588780 is a verified direct-fit replacement for ISUZU NPR, NQR, NRR, and ELF series trucks equipped with 4HK1 (5.2L) and 4JJ1 (3.0L) diesel engines. As a critical hydraulic component of the rear drum brake system, it converts hydraulic pressure from the master cylinder into mechanical force that pushes the brake shoes against the drum to slow or stop the vehicle.

The 4HK1 and 4JJ1 engines are widely used in Isuzu medium-duty commercial trucks from 2003 to 2021, including the NPR, NPR-HD, NQR, NRR, and ELF platforms. This wheel cylinder is the rear left (driver side) component and features an automatic slack adjuster mechanism that maintains correct brake shoe-to-drum clearance without periodic manual adjustment. On these Isuzu platforms, the rear left position uses two cylinders — a forward and a rearward unit — and this part serves as the rearward cylinder in that pair.

• Bore Diameter Verified: 1-5/16 in (33.34 mm / 1.313 in) — confirmed by Raybestos (33.35 mm / 1.313"), Blue Print (33 mm), and multiple independent suppliers (1-5/16").
• Position Verified: Rear Left (Driver Side) — confirmed by SKV ("ISUZU LHD Rear L"), Italian supplier ("Ruota posteriore sinistra"), and Russian catalogs ("задний левый").
• Adjuster Type Verified: Automatic slack adjuster — confirmed by Italian supplier ("regolazione automatica") and Raybestos design features.
• Bleeder Configuration Verified: Bleeder screw not included in standard configuration — confirmed by Russian listings ("без прокачки" / without bleeder) for both Yamasida and SKV variants.
• Material Verified: Cast Iron — confirmed by Blue Print (Material: Cast Iron) and Italian supplier ("ghisa" / cast iron).
• Weight Verified: 1.536 kg — confirmed by Blue Print (ADZ94434) specification.
• OEM Cross-Reference Verified: Replaces 8-97358878-0, 8973588780, 8-97358-878-0, 8973588781, 8-97358-878-1. International brand cross-references include Blue Print ADZ94434, Raybestos WC370238, SKV 8973588780, Yamasida 8973588780, ZEVS 8973588780, and JAPKO 67921.
• Paired Counterpart: Blue Print lists ADZ94433 as the paired article number (rear right counterpart).

• Brake fluid leak at wheel: Visible wetness around the backing plate or inside the brake drum — indicates seal failure and imminent braking loss.
• Spongy or long-travel brake pedal: Pedal sinks further than normal and feels soft — air enters the system through a failed seal, reducing hydraulic pressure.
• Uneven braking or vehicle pull: Vehicle pulls to one side during braking — one wheel cylinder is not applying equal force, causing imbalance.
• Brake fade or overheating drums: Extended stopping distances and hot brake drums — a failing cylinder may cause dragging or insufficient shoe application.
• Automatic adjuster failure: If the self-adjusting mechanism seizes or over-adjusts, brake drag or excessive pedal travel can result.

Confirmed Fitment Sources: GoTrucky confirms Isuzu NPR (2005–2009, 2011–2017 with 4HK1-TC / 4JJ1-TC), NPR-HD (2008–2018 with 4HK1-TC), NQR (2005–2018 with 4HK1-TC), and NRR (2005–2021 with 4HK1-TC). Raybestos confirms Isuzu N-Series (2004–2009, 2016–2018), Chevy Low Cab Forward (2016–2017), and W-Series (2004–2009). Fab Heavy Parts confirms NPR, NQR, ELF, 700P, and NPR75 with 4HK1 / 4HF1 engines.

Each unit undergoes 100% pressure testing before packaging. Manufacturing conforms to OEM specification standards for hydraulic brake components.

1. 1Safety first: Park on level ground, engage the parking brake, and chock the front wheels. Wear safety glasses and gloves.
2. 2Remove wheel and drum: Loosen the lug nuts, raise the vehicle, remove the wheel, and extract the brake drum. Inspect the drum and shoes for wear.
3. 3Disconnect hydraulic line: Place a drain pan underneath, disconnect the brake line from the wheel cylinder, and plug the line to prevent contamination.
4. 4Remove old cylinder: Unbolt the wheel cylinder from the backing plate. Note the orientation of the push rods and the auto-adjuster linkage for correct reassembly.
5. 5Clean mounting surface: Remove rust, dirt, and debris from the backing plate mounting area.
6. 6Install new cylinder: Position the new wheel cylinder (8-97358878-0) onto the backing plate and tighten the mounting bolts to specification.
7. 7Reconnect brake line: Connect the hydraulic line. Tighten to thread specification without over-torquing.
8. 8Install shoes and drum: Reinstall the brake shoes, adjuster components, and drum. Perform the automatic adjuster initialization procedure per the workshop manual.
9. 9Bleed the brake system: Fill the master cylinder reservoir with DOT 3 or DOT 4 brake fluid. Bleed until clear, bubble-free fluid flows. Note: This unit is supplied without a bleeder screw in standard configuration — ensure your bleeding method is compatible.
10. 10Test brakes: Pump the pedal to seat the shoes, check for leaks, and road-test at low speed before returning the vehicle to service.

• Inspect wheel cylinders every 40,000–50,000 km or during any brake service.
• Replace wheel cylinders in axle pairs — replacing only one side can cause uneven braking and pull to one side.
• Flush brake fluid every 2 years or according to the manufacturer interval.
• Verify auto-adjuster operation during every brake inspection — seized adjusters can cause drag or excessive pedal travel.

• Standard packing: Individual box with protective packaging; wooden pallet available for bulk orders.
• Package contents: 1 × Rear Left Brake Wheel Cylinder (installation hardware not included; bleeder screw not included in standard configuration).
• Set options: Left side only, or left + right pair — specify at inquiry.
• Suitable for: Brake system repair shops, fleet maintenance departments, spare parts distributors, and export wholesalers.
• Related parts available: Rear right wheel cylinder (ADZ94433 counterpart), rear left forward cylinder, brake shoes, brake drums, wheel cylinder repair kits, brake fluid (DOT 3 / DOT 4), and brake hardware kits.