Clutch Slave Cylinder 8-98004780-0 / 8-97349423-0 For ISUZU MYY5T 4HF1 4HG1 NKR NPR NQR71 — ISO/TS16949, OEM-Spec Replacement

The Clutch Slave Cylinder with OEM references 8-98004780-0 / 8-97349423-0 (condensed forms 8980047800 / 8973494230) is a verified replacement hydraulic actuator for ISUZU MYY5T (5-speed manual) gearboxes mated to 4HF1 (4.3L) and 4HG1 (4.6L) diesel engines, used across the NKR, NPR, and NQR71 light truck platforms. This cylinder is the hydraulic receiving unit at the gearbox end of the clutch system — it converts hydraulic pressure from the clutch master cylinder into mechanical force that moves the release fork, disengaging the clutch for gear changes.

Supplied under the YIMI brand, a recognized aftermarket supplier of Japanese commercial vehicle parts, the unit is manufactured under ISO/TS16949 quality management. It is confirmed as the complete assembly for the MYY5T / 4HF1 / 4HG1 application, featuring an M12 × 1.5 outlet thread and a reference actual size of 9 × 7 × 12 cm.

Confirm the following three specifications before ordering to ensure correct fitment:

1. MYY5T Gearbox Compatibility — This slave cylinder is confirmed for the MYY5T 5-speed manual transmission used in NKR, NPR, and NQR71 applications. Other ISUZU gearboxes (e.g., MYY6S, MZZ6) use different clutch release configurations. Confirm the gearbox code before ordering.
2. 4HF1 / 4HG1 Engine Application — Confirmed for 4HF1 (4.3L) and 4HG1 (4.6L) diesel engines. These engines share the same clutch hydraulic architecture in the MYY5T application, but confirm the engine code and VIN for mixed-fleet ordering.
3. Bore Specification Requires Physical Confirmation — Reference data shows two bore figures for this OE family: one parts listing states Ø 19.00 mm for the 8-98004780-0 reference, while Russian-market listings for the same 8973494230 family describe the cylinder as 1-inch (25.4 mm) in the context of related N-Series clutch slave cylinders. This discrepancy may reflect different production batches, market-specific variants, or a data labelling inconsistency. Measure the original cylinder's bore before ordering — a mismatched bore changes pedal effort and release travel.

• OE Reference Group Verified: 8-98004780-0, 8-97349423-0, 8980047800, and 8973494230 are consistently grouped as interchangeable references for the same ISUZU MYY5T / 4HF1 / 4HG1 clutch slave cylinder across multiple independent catalogs.
• Vehicle & Engine Coverage Verified: ISUZU 4HF1, 4HG1 engines; NKR, NPR, MYY5T, NQR71 applications — confirmed across factory-direct and aftermarket listings.
• Brand & Certification Verified: YIMI brand; ISO/TS16949 certification — confirmed by product specification data.
• Outlet Thread Verified: M12 × 1.5 — confirmed by Russian-market technical listings for the 8973494230 reference.
• Dimensions Verified (Actual Size): 9 × 7 × 12 cm — confirmed by factory-direct product data.
• Warranty Reference: 6 months (factory-direct data) / 1 year (alternate aftermarket reference) — confirm tier at inquiry.
• MOQ & Supply Reference: MOQ 10 pcs; supply capacity 1,000 sets/month; delivery 5–8 working days — confirmed by factory-direct data.
• Packaging Verified: Neutral package or customer-requested packaging — confirmed by supplier terms.
• ⚠️ Bore Diameter Discrepancy: Reference data shows Ø 19.00 mm (one parts listing) versus 1-inch / 25.4 mm (related Russian-market listing for the same OE family). This is the single most critical specification to confirm against the original cylinder before ordering. Do not assume one bore applies to all variants without physical verification.

• Clutch pedal sinks to the floor or feels spongy: Internal seal failure allows hydraulic pressure to bypass, preventing full clutch disengagement — the most common symptom of a failing slave cylinder.
• Difficulty selecting gears / gear clash: Insufficient hydraulic pressure means the clutch does not fully disengage, causing hard shifting and gear grinding.
• Fluid leak at the gearbox bellhousing: A failed slave cylinder seal allows clutch fluid to escape, often visible as wetness or drips at the gearbox-engine joint.
• Clutch pedal does not return fully or has a low engagement point: A worn internal seal or pushrod prevents the pedal from returning to its rest position.
• Fluid level dropping in the clutch reservoir without an external leak: Internal seal bypass can allow fluid to enter the pushrod boot area or the bellhousing.
• Clutch drag / vehicle creeps when in gear with pedal depressed: If the cylinder cannot fully release the pressure plate, the clutch drags, causing hard shifting and accelerated clutch wear.

• Gearbox code is the first check: This cylinder is confirmed for MYY5T (5-speed manual). Other ISUZU gearboxes use different clutch release configurations. Confirm the gearbox code before ordering.
• Bore diameter must be verified: Reference data shows Ø 19.00 mm and 1-inch (25.4 mm) for the same OE family. Measure the original cylinder's bore — a mismatched bore alters pedal effort and release travel.
• Engine coverage: Core engines are 4HF1 and 4HG1. Provide the VIN for final confirmation in mixed-fleet applications.
• MYY5T vs. other MYY variants: The MYY5T is a 5-speed unit. The MYY6S (6-speed) uses a different clutch hydraulic configuration. Do not interchange MYY5T and MYY6S slave cylinders without verifying the gearbox code.

1. Confirm the required part first: Verify the original slave cylinder's bore diameter, outlet thread (M12 × 1.5), and gearbox code (MYY5T). Compare the pushrod length and mounting flange to the replacement.
2. Disconnect the hydraulic line: Place a drain pan underneath, disconnect the fluid line from the slave cylinder, and plug the line immediately to prevent contamination.
3. Remove the mounting bolts: Unbolt the slave cylinder from the transmission bellhousing. Note the orientation of the pushrod and any return spring.
4. Bench-bleed the slave cylinder (recommended): Fill the cylinder with clean clutch fluid and bleed it on the bench before installation to reduce in-vehicle bleeding time.
5. Install the new cylinder: Position the 8-98004780-0 / 8-97349423-0 cylinder on the transmission, insert the mounting bolts, and torque to the workshop manual specification.
6. Reconnect the hydraulic line: Connect the fluid line to the M12 × 1.5 outlet and tighten without over-torquing.
7. Bleed the clutch system: Fill the clutch master cylinder reservoir with the specified fluid and bleed until clear, bubble-free fluid flows from the bleeder screw. Air in the circuit is the leading cause of post-replacement clutch drag.
8. Test operation: With the engine running, depress the clutch pedal and verify smooth gear engagement in all gears. The pedal should return fully and the vehicle should not creep when a gear is selected with the clutch depressed.

• Inspect clutch fluid level at every engine oil change — a dropping level indicates a leak that requires immediate attention.
• Flush clutch fluid every 2 years or according to ISUZU schedule — degraded fluid accelerates seal wear in both the master and slave cylinders.
• Check for leaks at the slave cylinder body, bleeder screw, and hydraulic line fitting during routine inspection.
• Replace the slave cylinder at the first sign of a spongy pedal or external leak — do not "top up and monitor" a known-failing hydraulic component on a commercial truck.

• Standard packing: Neutral package or customer-requested packaging — confirmed by supplier terms.
• Package contents: 1 × Clutch Slave Cylinder. Pushrod, bleeder screw, mounting hardware, and clutch fluid are not included unless explicitly stated — confirm exact package contents at inquiry.
• Set options: Cylinder only (standard) / cylinder + pushrod kit (where available) — specify at inquiry.
• Suitable for: ISUZU NKR / NPR / NQR71 clutch and gearbox repair shops, commercial truck fleet maintenance departments, driveline rebuilders, spare parts distributors, and export wholesalers.