The Genuine SINOTRUK ZF Transmission Synchronizer Ring (1297 333 137) is the single most critical wear component ensuring that every shift is smooth, silent, and efficient. As a high-precision item among sinotruk spare parts, this ring functions as a friction brake, instantly matching the rotational speed of the gear to the shaft before mechanical engagement. This process is the core of synchronization, preventing the destructive metal-on-metal clash that leads to premature transmission failure.

Technical Specifications

The 1297 333 137 synchronizer ring is a precision-forged component designed for the extreme demands of the ZF Ecosplit transmission family.

Specification	Value
Part Number	1297 333 137
Alternative Names	Synchro Ring, Blocking Ring
Product Name	Synchronizer Ring
Application	ZF 16S Series Transmissions (e.g., 16S151, 16S221)
Compatible Vehicles	SINOTRUK HOWO, SITRAK, and other trucks using ZF 16S gearboxes
Brand	ZF (Original OEM Specification)
Material	High-Strength Forged Steel with High-Performance Friction Lining (e.g., Molybdenum)
Function	Speed equalization and blocking function during gear shift
Weight (Approx.)	0.750 KG
Condition	Brand New

Installation Notes

The replacement of a synchronizer ring is a highly specialized task requiring complete transmission disassembly. This work must be performed by a certified transmission specialist in a clean, controlled environment.

1.Transmission Disassembly: The gearbox must be removed from the vehicle and placed on a stable stand. Accessing the synchronizer ring requires the main shaft to be disassembled. Maintain absolute cleanliness throughout the process, as contamination can destroy the new friction surface.

2.Component Inspection: Before installing the new 1297 333 137 ring, thoroughly inspect the mating cone hub (e.g., 1316.304.190) for any signs of scoring, glazing, or damage. If the hub is damaged, the new ring will fail prematurely.

3.The Critical Clearance Check: Place the new ring onto the cone hub. Using a feeler gauge, measure the synchronizer clearance (the gap between the ring and the hub). This clearance must meet the minimum tolerance specified in the ZF service manual (typically >0.8mm for new parts). If the clearance is too small, the ring is defective or the hub is worn.

4.Installation and Lubrication: Lightly lubricate the friction surface of the new ring with the specific ZF-approved transmission oil. Position the ring onto the cone hub, ensuring the external blocking teeth are correctly aligned with the synchronizer sleeve’s sliding blocks.

5.Final Reassembly: Reassemble the transmission, ensuring all components are torqued to factory specifications. Use new gaskets and seals.

6.Testing: After reinstallation, test the gear engagement in all positions. A successful repair is indicated by smooth, low-effort, and silent shifting.