Truck Gearbox Synchronizer Ring 1789444 1304850 for SCANIA

The 1789444-1304850 synchronizer ring is an OEM-spec replacement synchronizer ring for truck gearbox synchronizer ring 1789444 1304850 for scania – tosen auto. TOSEN AUTO supplies it as a factory-built unit and 100% inspected before dispatch, ready to install. This page gives you the full specification, compatibility, failure symptoms, installation notes and maintenance guidance so you can confirm fitment and source with confidence — no marketing fluff, only the technical facts you need to make a buying decision.

Confirm fitment by the OEM part number and the engine code, not by the vehicle model alone. The same vehicle platform often runs several engine codes over its production life, each requiring a different synchronizer ring. Cross-check the OEM number stamped on your original part before ordering — ordering by model name is the single most common cause of receiving a wrong part. If you are unsure, send us the OEM number and engine code and we will confirm fitment before you commit.

A synchronizer ring is the friction cone that matches the speed of a gear to the input shaft before the engagement dogs lock together. Without it, shifting would grind every time. The ring’s cone face provides the friction, and its internal splines have blocking teeth that prevent engagement until speeds match. Worn friction lining or rounded blocking teeth are why a gear grinds or pops out — and once metal circulates, the whole synchro assembly (ring, slider, hub) usually needs replacing as a set.

This synchronizer ring is stamped or powdered-metal-formed from brass or steel (per OEM spec) with a friction lining on the cone face where applicable. The cone angle and the spline geometry are machined to OEM tolerance so the ring meshes with the engagement teeth and the slider hub without backlash. Every ring is inspected for cone concentricity, spline fit and friction-surface finish. We do not sell reground rings — a worn synchro ring must be replaced, not reused.

• Grinding when shifting into a gear — the cone can no longer match shaft speeds before engagement.
• Hard shifting, cold that improves warm — a worn friction lining.
• Popping out of gear under load — worn engagement dogs, often alongside the synchro ring.
• Buzzing or clicking during shift — the ring is spinning against the dog without gripping.

1. Inspect the slider hub and engagement teeth — replace as a set if the dogs are rounded.
2. Use the correct gear oil — wrong friction modifier ruins synchro cones.
3. Check end play after reassembly; a wrong snap ring selection causes jump-out.

Synchronizer rings wear with every shift, so their life is driven by driving style and oil quality. Avoid forcing shifts, use the correct gear oil, and change it on schedule. Grinding is the warning — driving through it rounds the engagement dogs and turns a ring replacement into a full synchro-assembly rebuild.

This synchronizer ring is used in gearbox rebuilds where one or more gears grind on engagement. It is fitted during a synchro-assembly service — alongside the slider, hub and bearings — not as a standalone part. Common scenarios: a truck gearbox that grinds into third under load; a passenger car that pops out of gear on deceleration; a fleet gearbox being rebuilt preventively at a set interval. The ring is matched to the gear set and the oil grade; the wrong friction material or oil causes repeat failure.

Every synchronizer ring is 100% inspected before dispatch. The cone angle is checked for concentricity; the spline geometry is checked for fit to the engagement teeth; the friction surface is inspected for finish and (where lined) for lining bond; and the blocking teeth are checked for squareness. A ring with rounded blocking teeth or a flawed cone is scrapped. Batch samples are dimensionally reported.

TOSEN AUTO supplies this part factory-direct to overseas distributors and workshops, with sample orders accepted for qualification and volume pricing from MOQ. Each unit is individually protected — corrosion-inhibited, sealed and packed in rigid export cartons with foam bracing — to arrive undamaged after long-distance freight. A warranty against manufacturing defects applies from the date of dispatch; in the rare event of a defect, send us the batch number and photos and we will resolve it under the warranty terms. Lead time on stock items is 3–5 working days; air freight to most destinations 7–12 days.

• OEM-spec build — correct geometry, tolerances and material for the 1789444-1304850 application, not a generic part.
• 100% inspected (runout, tolerance, finish) before dispatch.
• Factory-direct B2B pricing from TOSEN AUTO; sample orders accepted for qualification.
• Flexible MOQ and export packaging for overseas distributors.