2018 Ford Transit — Transmission & Axle Gear Ratios

Transmission gear ratios

2018 Ford Transit vans in North America use the 6-speed SelectShift automatic (6R80 family) across T-150, T-250, and T-350/350 HD. Ratios are identical regardless of engine (3.7L Ti-VCT V6, 3.5L EcoBoost V6, or 3.2L I-5 Power Stroke diesel).

6-speed automatic (6R80/SelectShift)

Notes:

• All 2018 U.S.-market Transits are automatic; a manual gearbox was not offered here for 2018.
• SelectShift allows manual +/- command but the internal ratios are fixed as shown.

Available axle ratios

Ford offered multiple rear axle ratios depending on GVWR, engine, roof/wheelbase, and towing package. Limited-slip (Traction-Lok) was optional on many builds. Axle codes on the door-jamb label identify the exact configuration (see below).

Notes:

• Actual availability varies by wheelbase, roof height, GVWR, GCWR, and country. Always verify your specific van’s AXLE code.
• Ratios like 3.55 or 4.30 are common on other Ford trucks but were not standard offerings on most U.S.-market 2018 Transits.

How to identify your axle ratio

You have a few reliable ways to confirm what’s under your Transit:

• Door-jamb certification label: On the driver’s door jamb, find the Ford vehicle certification label. Look for the box labeled “AXLE.” This two-character axle code corresponds to your ratio and whether it’s open or Traction-Lok (limited slip). Example conventions frequently seen on Transits include 52/62 (3.31), 53/63 (3.73), and 54/64 (4.10), where the 6x codes typically indicate Traction-Lok. Cross-check the code in a Ford axle chart for certainty.
• Axle tag: A metal tag is attached under a differential cover bolt or on the axle housing. It will list the ring-and-pinion tooth count or a stamped ratio (e.g., “3 31,” “3 73,” “4 10”). Counting teeth (e.g., 41/11 = 3.73) confirms the ratio.
• VIN build data/window sticker: A Ford VIN decoder or an official build sheet/window sticker (Monroney) will list the rear axle ratio and whether limited slip was installed. A Ford dealer can also pull the as-built data.

Towing vs MPG impact

• Numerically lower axle ratios (e.g., 3.31) reduce engine rpm at highway speeds, improving fuel economy and cabin noise while lightly loaded. The trade-off is less torque multiplication at the wheels, so launch with heavy cargo or on steep grades can feel lazier, and max trailer/GCWR ratings may be lower.
• Middle ratios (3.73) strike the most balanced setup for mixed city/highway driving, routine payloads, and moderate trailers—common on T-250/T-350 fleet builds.
• Higher ratios (4.10) spin the engine faster at a given road speed, which improves low-speed pull, grade-holding, and GCWR for heavy towing, RV upfits, and ambulance/HD prep packages. Expect a noticeable fuel-economy penalty in highway cruising.
• Transmission interaction: Because the 6R80 has deep 1st (4.17) and double overdrives (0.87/0.69), even a 4.10 axle will cruise reasonably at speed in top gear, while a 3.31 still gets strong launch thanks to the 4.17 first gear.

Common issues

While the 2018 Transit powertrain is generally durable, owners and shops report a few recurring driveline items:

• 6R80 transmission
  • Torque converter shudder or light-speed vibration at steady cruise in 5th/6th. Often improved with updated fluid (Mercon LV), a flush, and TCM calibration; severe cases may need a converter.
  • Harsh 2–3 or 3–4 shifts and delayed engagement when hot: can be valve body wear or molded leadframe/OSS sensor issues. Updated leadframe assemblies and reprogramming address many cases.
  • Pan leaks after service if the integrated pan/filter isn’t torqued evenly or the gasket is damaged.
• Rear axle/differential
  • Ring-and-pinion whine at 45–65 mph on light throttle, especially after fluid neglect or towing. Proper setup and quality gear oil help; persistent whine may require a gear set and bearings.
  • Pinion seal seepage; look for sling on the underbody. Replace seal and set correct preload.
  • Limited-slip (Traction-Lok) clutch chatter on tight turns if friction modifier is depleted; refresh with correct additive or service the unit.
• Prop shaft/support
  • Center (carrier) bearing wear on long-wheelbase/multi-piece driveshafts causes vibration on launch or at 35–55 mph. Replacement bearing and driveshaft re-balance typically cures it.

Pro tips:

• For heavy tow duty, pair the 3.5L EcoBoost or 3.2L diesel with 3.73 or 4.10, keep transmission fluid fresh, and service the rear axle at sensible intervals (e.g., 30–60k when towing).
• If chasing a whine, verify tire cupping and wheel bearings before condemning gears.

Find a driveline shop on Repairius.