2018 Mercedes‑Benz Sprinter — Transmission & Axle Gear Ratios

Transmission gear ratios

2018 Mercedes‑Benz Sprinter (NCV3, U.S.-spec) offered two automatic transmissions depending on engine. Ratios below are the internal gear ratios of each gearbox.

5G‑TRONIC (W5A380 / 722.6) — 5‑speed automatic, typically with 3.0L V6 OM642

7G‑TRONIC PLUS (722.9) — 7‑speed automatic, typically with 2.1L I4 OM651

Note: Overall road ratio in any gear is Transmission Ratio × Axle (final drive) Ratio. Always verify your exact equipment by VIN.

Available axle ratios

Final drive (rear axle) options varied by weight class and engine. The entries below reflect common U.S. 2018 Sprinter configurations; limited fleet/cab‑chassis specs may differ by build.

Tip: Mercedes‑Benz doesn’t use GM‑style RPOs; the official “data card” attached to your VIN lists the axle as “Axle ratio i = X.XXX.”

How to identify your axle ratio

• Mercedes‑Benz Sprinter (best method): Use your VIN to pull the factory data card. A Mercedes dealer or online EPC/decoder will list an entry like “Axle ratio i = 4.182.” This is definitive for your van as built.
• Axle tag/etching: Many Sprinter rear axles have a small metal tag or stamping on the differential housing that includes the ratio (often shown as “i=3.923”). You can also count ring‑and‑pinion turns with the wheels raised if tags are missing.
• Door‑jamb stickers: GM vehicles use an RPO sticker in the door jamb (codes like GU6, GT4). Sprinters do not; use the VIN data card instead.
• Ford/Ram style tags: Ford and Ram often place a metal tag on the axle with a code (e.g., 3L73). If you’re cross‑shopping or swapping parts, note that Mercedes uses the “i = X.XXX” convention rather than those codes.
• VIN decoders: Quality Mercedes VIN decoders and EPC services can surface the axle ratio and differential type by VIN for 2018 Sprinter models.

Towing vs MPG impact

• Lower numeric ratio (e.g., 3.92) = lower engine RPM at cruise. Expect better highway fuel economy and quieter cruising, but less mechanical advantage off the line and on grades.
• Higher numeric ratio (e.g., 4.18 or 4.36) = stronger launch and better gradeability/towing at the expense of higher RPM on the highway and slightly reduced MPG.
• Transmission pairing matters: The 7G‑TRONIC’s two overdrives (0.82 and 0.73) let you run a slightly higher axle (like 4.18) without excessive cruise RPM. The 5G‑TRONIC’s single overdrive (0.83) benefits more from a 3.92 axle if you prioritize economy.
• Payload and tire size affect effective gearing. Larger‑diameter tires act like a taller (lower‑numeric) axle; added weight pushes you toward a higher‑numeric axle for drivability.

Common issues

While Mercedes driveline components are generally robust, age and mileage can introduce typical rear‑axle and driveline concerns:

• Ring & pinion whine: A light coast or cruise whine between 40–60 mph can come from wear patterns, improper lash, or deteriorated pinion bearings. Verify correct fluid spec and level first; persistent noise calls for setup inspection (pattern, preload, backlash).
• Carrier/center support bearing (two‑piece driveshaft): Sprinters commonly develop vibration or a “rumble strip” feel as the rubber isolator cracks or the bearing wears. Inspect U‑joints and the center support; replace as an assembly if play or torn rubber is present, and re‑index shafts to maintain balance.
• Limited‑slip clutch wear (if equipped): Some builds include a clutch‑type LSD. Symptoms include chatter on tight turns or one‑wheel peel under load. Fresh fluid with the correct friction modifier may help; worn packs require overhaul.
• Seal leaks: Pinion and axle‑shaft seal seepage is not unusual with mileage. Address early to prevent fluid loss and bearing damage.

Pro tip: After any ring‑and‑pinion service, use the correct MB‑approved gear oil, follow proper setup specs, and perform a careful break‑in to minimize noise.

Find a driveline shop on Repairius.