Genuine ZF Part 1250304396 3rd4th Gear Synchronizer Hub Heavy-Duty ZF Parts Dealer

Genuine ZF Part 1250304391 Synchronizer Ring for Manual Transmissions | OEM ZF Parts Supplier

In the world of heavy-duty transmissions, the 3rd and 4th gear transition is the most frequently cycled range. If your gearbox is struggling to stay in gear or experiencing “notchy” shifting, the synchronizer hub is often the root cause. The ZF 1250304396 Synchronizer Hub is the central component that holds the sliding sleeve and synchronizer rings, acting as the mechanical heart of the shifting process.

As a specialized ZF parts dealer, we’ve seen the damage caused by low-quality aftermarket hubs—they often suffer from micro-cracks or spline failure under high torque. This genuine ZF part is forged from high-tensile steel and machined to zero-tolerance specifications. Choosing an authorized ZF parts supplier ensures that the internal splines perfectly match your main shaft, preventing the vibration and wear that leads to catastrophic gearbox failure.

Technical Specification

• Brand: ZF Transmissions (Genuine OEM)

• Part Number: 1250304396

• Component Type: Synchronizer Hub (3rd & 4th Speed)

• Compatibility: Fits a wide range of ZF Ecosplit, New Ecosplit, and Midliner gearboxes.

• Material: Forged and Case-Hardened Alloy Steel

• Internal Splines: Precision-cut for exact main shaft fitment.

• Service Life: Engineered for over 1 million shift cycles under standard load.

Simple Install Tip:

1. Check for Directionality: Many ZF hubs are not symmetrical. Look for a small notch or a stamped “arrow” on one side of the 1250304396 hub. Installing it backward will cause the sliding sleeve to bind and may prevent the gearbox from engaging 4th gear entirely.

2. Inspect the Internal Splines: Before sliding the hub onto the main shaft, check the shaft splines for any “stepping” or burrs. A new hub on a damaged shaft will eventually develop play, leading to gear pop-out.

3. Pressure Plate & Springs: When rebuilding the hub assembly, always use new synchronizer springs and pressure plates (dogs). Reusing old, weakened springs can lead to poor synchronization even with a brand-new hub.

4. The Snap-Ring Seat: Ensure the snap ring is fully seated in its groove after the hub is pressed on. Use a brass drift to gently tap the hub to ensure it is bottomed out before locking it in place.

Packaging & Shipping

By Express :     Suitable for sample order or <50 KG        Fast:3-10 days       High shipping cost         Door to door service
By Air :   Suitable for >50 KG         Fast: 3-7 days       Lower than express cost         Airport to airport service
By Sea:   Suitable for >300 KG     Lower cost port to port service

As a leading supplier and dealer of ZF parts, we provide genuine components to maintain the integrity and efficiency of your gearbox system. Trust in our expertise and quality assurance to keep your ZF gearbox running smoothly.