ISUZU NKR77 4JB1 Clutch Release Bearing Seat 8-97255313-0 OEM Fit

The Clutch Release Bearing Seat (Shift Block) with OEM numbers 8-97255313-0 and 8972553130 is a verified direct-fit replacement for ISUZU NKR77 / NPR70 / 700P series trucks equipped with 4JB1 / 4HG1 / 4HE1 / 4JH1 / 4HF1 / 4HK1 / 4JJ1 diesel engines. This component is the core guide and carrier element of the clutch release mechanism, mounted on the tubular extension of the transmission first-shaft bearing cover. It supports the release bearing, guides its precise axial sliding movement, and transmits release force from the release fork.

The release bearing seat is loosely fitted over the transmission first-shaft bearing cover extension. Its shoulder is kept in contact with the release fork by the return spring. When the clutch pedal is depressed, the release fork pushes the seat axially forward, and the seat in turn pushes the release bearing against the diaphragm spring, releasing the clamping force on the clutch disc and cutting off power flow. When the pedal is released, the return spring pulls the seat back to its rest position, maintaining approximately 3–4 mm clearance between the fork end and the seat, ensuring full clutch engagement and preventing the release bearing from continuously spinning with the engine.

This part is manufactured from heat-treated alloy steel or high-precision composite materials, offering excellent wear resistance, dimensional stability, and impact resistance to withstand the high-frequency release shocks and continuous vibration of heavy-duty commercial vehicle clutches.

The 8-97255313-0 is a widely applied release bearing seat model in the ISUZU ELF/NPR series. According to application data from CENS and OKISUZU, the same part number covers 4JB1 / 4HG1 / 4HE1 / 4HK1 / 4JJ1 / 4JH1 / 4HF1 engines and a wide range of models including NKR55 / NKR77 / NPR70 / NPR70PL / NMR85 / NPR75 / NPR85 / 700P. The specific engine model and transmission configuration must be confirmed against the VIN or original component before ordering.

Replace the release bearing seat when any of these symptoms appear:

• Difficulty engaging gears or incomplete clutch disengagement — worn or deformed guide surface causes the release bearing to tilt and insufficient travel.
• Clutch pedal noise or vibration — worn contact surface between the seat and release fork produces metallic knocking or friction noise.
• Premature release bearing failure — an out-of-round or rough guide surface causes bearing misalignment, overheating, or binding.
• Poor release fork return — a seized seat or worn shoulder prevents proper fork return, resulting in abnormal clearance.
• Visible cracks, deformation, or severe scoring on the guide surface — structural damage or surface failure requiring immediate replacement.
• Clutch slipping or engagement shock — the seat cannot maintain correct position, causing the release bearing to continuously contact or intermittently impact the diaphragm spring.

1. Preparation: Disconnect the battery negative terminal. Raise the vehicle and support the transmission. Remove the driveshaft and transmission.
2. Removal: Remove the release bearing and bearing seat from the first-shaft bearing cover. Inspect the seat guide surface, shoulder, and fork contact point for wear.
3. Inspection: Inspect the transmission first-shaft bearing cover guide surface for scoring or out-of-round. Check the release bearing for smooth rotation and noise. Inspect the release fork and ball stud for wear. If the guide surface is damaged, the bearing cover must also be replaced.
4. Installation: Apply high-temperature grease to the seat guide surface and fork contact point. Fit the seat loosely over the first-shaft bearing cover extension, ensuring the shoulder correctly contacts the release fork.
5. Transmission Reinstallation: Install the transmission and connect the driveshaft. Check and adjust the release fork clearance to approximately 3–4 mm.
6. Pedal Check: Verify clutch pedal free play meets specification.
7. Road Test: Start the engine and test gear engagement in all gears for smoothness, complete clutch disengagement, and absence of abnormal noise.

• Every 10,000 km: Note any change in shift feel or clutch pedal noise.
• Every 40,000–50,000 km: Check for complete clutch disengagement; whenever the release bearing is replaced, the seat must be inspected.
• At clutch kit replacement: Always inspect and replace the seat, release fork, and ball stud as necessary.
• When release bearing noise or hard shifting is detected: Inspect the seat and guide surface immediately.

• Standard Packaging: Anti-rust oil + VCI film + neutral carton.
• Custom Packaging: Neutral box, color box, or customer-branded packaging.
• Suitable For: Clutch/transmission repair shops, ISUZU parts distributors, fleet maintenance centers.
• Supply Capacity: Stable batch supply with batch-level quality reports available.
• MOQ: Small quantities accepted (quantity discounts available).