High-strength cast iron Front Brake Wheel Cylinder with 1-3/16" bore diameter for ISUZU NPR 4HF1 — Direct OEM replacement
| Thread Size: | M10×1 | Gear Teeth: | 16 Teeth |
| Mounting Hole Spacing: | 52mm | Net Weight: | 1.09kg |
| Bore Diameter: | 1-3/16" (30.16mm) | Mounting Diameter: | 34mm |
| Material: | High-strength Cast Iron | Bolt Torque: | 15–18N·m |
| High Light: | High-strength cast iron Brake Wheel Cylinder,1-3/16" bore diameter Wheel Cylinder,Direct OEM replacement Front Brake Wheel Cylinder |
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The Front Brake Wheel Cylinder with OEM numbers 8971398210 / 8-97139821-0 is a verified direct-fit replacement for ISUZU NPR series trucks equipped with the 4HF1 engine. This wheel cylinder is a critical component of the drum brake system, responsible for converting hydraulic pressure from the brake master cylinder into mechanical force that pushes the brake shoes against the brake drum, slowing or stopping the vehicle.
When the driver presses the brake pedal, brake fluid flows from the master cylinder through the brake lines into the wheel cylinder. The hydraulic pressure forces the pistons inside the cylinder outward, pushing the brake shoes against the inner surface of the brake drum. Friction converts the vehicle's kinetic energy into heat, achieving braking. When the pedal is released, return springs retract the pistons, releasing the brakes.
- Brake Fluid Leakage — Visible oil stains around the wheel cylinder; brake fluid level drops consistently
- Vehicle Pulls to One Side — Vehicle veers to one side during braking; single-side cylinder sticking
- Low/Spongy Brake Pedal — Increased pedal travel; reduced braking force
- Brake Noise — Metallic grinding or squealing during braking
- Brake Drag — Vehicle feels like brakes are still applied after releasing pedal; pistons fail to retract
- Installation Success Rate: 98.7% direct bolt-on fitment — confirmed across 127 repair orders (Jan 2024 – Jun 2025)
- Bench Durability Test: 500,000 full-stroke pressure cycles (0–10MPa) — zero leakage, piston stroke degradation <3% (Test Report #BWC-8971398210-2024)
- Pressure Seal Integrity: 15MPa static pressure held for 30 seconds — zero pressure drop; 100% factory tested (ISO 6117)
- Bore Precision: 1-3/16" (30.16mm) precision-honed cylinder bore, surface roughness Ra≤0.4μm — CMM verified
- Material Verification: High-strength cast iron body, hardness HB190–230 — material spectrographic analysis report included
| Brand | Model | Chassis | Engine | Years |
|---|---|---|---|---|
| ISUZU | ELF 250 | NKR66 | 4HF1 | 1994–1998 |
| ISUZU | ELF 350 | NQR55/58/59/65/66/69/70/71 | 4HF1 | 1994–2000 |
| ISUZU | NPR | NPR55/58/66/69/70/71 | 4HF1 | 1994–2000 |
| ISUZU | NPR | NPR250 | 4HF1 4.3L | 1993–2006 |
- This is a FRONT brake wheel cylinder (Front Left / Front position)
- Confirm your vehicle has drum brake system before purchase
- Recommended to replace both left and right wheel cylinders simultaneously for balanced braking
- For 100% accurate fitment, please provide VIN (Chassis Number)
| Feature | Benefit + Verification Signal |
|---|---|
| High-Strength Cast Iron Body | Withstands high pressure and thermal cycling — verified by 500-hour thermal cycle test (-30°C to +150°C); no cracks, no deformation |
| Precision-Honed 1-3/16" Bore | Ensures smooth, consistent hydraulic pressure transfer for responsive, reliable braking — bore roundness ≤0.005mm, Ra≤0.4μm; CMM verified |
| 100% Pressure Leak Tested | Every cylinder undergoes 15MPa air/hydraulic dual leak test — 30-second hold with zero pressure drop; 100% pass rate (ISO 6117) |
| Direct OE Fit Replacement | No modification needed for quick, hassle-free installation — 98.7% bolt-on fitment rate confirmed across 127 repair orders |
| Includes Bleeder Screw & Gear Adjuster | Easy brake system bleeding and shoe gap adjustment — 16-tooth adjustment gear for convenient maintenance |
| 12-Month / 50,000 km Warranty | Peace of mind on manufacturing defects — free replacement within warranty period |
| QC Item | Verification Method | Standard |
|---|---|---|
| Material Composition | Spectrographic analysis | Meets HT250 cast iron standard |
| Body Hardness | Brinell hardness tester | HB190–230 |
| Bore Dimensional Accuracy | CMM coordinate measuring machine | 30.16±0.013mm |
| Bore Surface Finish | Roughness tester | Ra≤0.4μm |
| Pressure Leak Test | Air + hydraulic dual test | 15MPa hold 30s zero leak (ISO 6117) |
| Piston Sliding Resistance | Universal testing machine | ≤3.5N (dry condition) |
| Durability Test | Bench cycle test | 500,000 full-stroke pressure cycles no failure |
| Visual & Dimensional Inspection | 100% visual + gauge inspection | No porosity, blowholes, or burrs |
- Safety Prep: Park on level ground, chock wheels, lift and support vehicle
- Remove Old Cylinder: Disconnect brake line (catch draining fluid), remove mounting bolts (2*M10 bolts, torque 15–18N·m)
- Clean Mounting Surface: Thoroughly remove rust and debris from mounting face
- Install New Cylinder: Mount new cylinder, torque bolts to 15–18N·m
- Connect Brake Line: Attach brake hard line, torque to 14–16N·m
- Bleed Brake System: Bleed in sequence (RR → LR → RF → LF) until no air bubbles appear
- Adjust Clearance: Use the 16-tooth adjustment gear on the cylinder to set proper brake shoe clearance
- Road Test: Perform brake test at 30km/h — confirm smooth braking, no pulling, no noise
| Item | Interval |
|---|---|
| Brake Fluid Replacement | Every 2 years or 40,000 km |
| Wheel Cylinder Inspection | Every 10,000 km or 6 months |
| Brake Shoe Inspection | Every 10,000 km |
| Cylinder Replacement | When leakage/sticking occurs, or at 80,000–100,000 km |
- Packaging: Neutral carton / Color box / Custom branded packaging
- Packaging Unit: 1 piece/box
- Carton Dimensions: 12*10*7cm
- MOQ: Small orders accepted; volume discounts available
- Target Customers: Truck parts wholesalers, repair chain stores, fleet purchasers, cross-border e-commerce sellers
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