2015 Ford Transit: Transmission & Axle Gear Ratios Guide

When Ford introduced the full-size Transit van to the North American market in 2015 to replace the legendary E-Series, it brought a completely modernized powertrain lineup. Whether you are driving the naturally aspirated 3.7L V6, the torquey 3.5L EcoBoost V6, or the efficient 3.2L Power Stroke diesel, understanding your van's transmission and axle gear ratios is crucial for maximizing its potential.

Below is a comprehensive guide to the transmission and axle specifications for the 2015 Ford Transit, designed to help fleet managers, tradespeople, and RV converters understand exactly how their van is geared.

Transmission gear ratios

For the 2015 model year, Ford equipped all Transit models—regardless of the engine choice or chassis configuration—with the robust and proven 6R80 6-speed automatic transmission. Originally developed for high-torque applications like the F-150, the 6R80 features a wide gear spread to balance heavy-duty low-end pulling power with highway fuel efficiency.

6R80 6-Speed Automatic Transmission

Note: The deep 4.17:1 first gear provides excellent off-the-line torque multiplication for heavily loaded vans, while the dual overdrive gears (5th and 6th) keep engine RPMs low during highway cruising.

Available axle ratios

The rear axle ratio is the final piece of the gearing puzzle, dictating how many times the driveshaft must turn to rotate the rear wheels once. Ford offered three primary axle ratios for the 2015 Transit, available in both open differential and Limited-Slip Differential (LSD) configurations.

Note: Axle codes can vary slightly based on dual rear wheel (DRW) vs. single rear wheel (SRW) configurations.

How to identify your axle ratio

If you are buying a used 2015 Transit or planning a heavy tow, you need to verify the rear axle ratio currently installed on the van. Here are the most reliable ways to find out:

1. The Door-Jamb Sticker: Open the driver’s side door and look for the Safety Compliance Certification Label on the B-pillar. Locate the field labeled "AXLE" along the bottom edge. You will find a two-digit alphanumeric code. Common 2015 Transit codes include "73" for a 3.31 open diff, "7X" for a 3.73 open diff, and "3L" or "4L" for limited-slip versions.
2. The Axle Tag: Ford traditionally attaches a metal identification tag to one of the bolts on the differential cover. The bottom line of this tag typically starts with the ratio. For example, a tag reading "3 73" indicates a 3.73 open differential, while "3L73" indicates a 3.73 limited-slip differential.
3. VIN Decoder: If the door sticker is faded or the axle tag is missing, running your 17-digit Vehicle Identification Number (VIN) through a comprehensive Ford VIN decoder or calling a local dealership parts department will provide the original build sheet, including the factory axle ratio.

Towing vs MPG impact

Choosing or understanding your axle ratio is a balancing act between mechanical leverage and engine speed.

• Numerically lower ratios (e.g., 3.31): Often referred to as "tall" gears, these require the driveshaft to spin fewer times per wheel revolution. This keeps engine RPMs lower at highway speeds, resulting in better fuel economy and less engine noise. However, it sacrifices low-end grunt, making it harder to pull heavy trailers off the line or ascend steep grades.
• Numerically higher ratios (e.g., 4.10): Known as "short" or "deep" gears, these provide maximum mechanical leverage. This makes a heavily loaded van feel much more responsive and vastly improves towing capability. The trade-off is higher cruising RPMs on the highway, which noticeably decreases fuel efficiency and increases cabin noise.
• The Middle Ground (3.73): This is the most common ratio for a reason. It provides enough low-end torque for daily contracting work and moderate towing, without heavily penalizing highway fuel consumption.

Common issues

The 2015 Ford Transit drivetrain is generally robust, but there are a few documented issues to keep an eye on, particularly as these vans accumulate high mileage:

• Driveshaft Guibo / Flex Disc Wear: Early Transits (including 2015 models) had a widely known issue with the flexible polyurethane coupling (guibo) connecting the transmission to the driveshaft. If this tears or cracks, it causes severe driveline vibration and clunking. Ford issued a recall for many of these, eventually replacing them with a traditional U-joint setup on later models.
• Carrier Bearing Failure: Long-wheelbase Transits utilize multi-piece driveshafts supported by center carrier bearings. These bearings can wear out over time, leading to a noticeable shudder or thumping sensation directly beneath the floorboards upon acceleration.
• Limited-Slip Clutch Wear: If your Transit is equipped with a limited-slip rear differential, the internal clutch packs will eventually wear out, especially if the van is frequently driven fully loaded or used in low-traction environments. Symptoms include "chatter" or groaning noises from the rear end when making tight turns. Changing the differential fluid and ensuring the proper friction modifier is added can often resolve minor chatter.

Find a driveline shop on Repairius

Whether you need to service a whining differential, upgrade your van's ring and pinion gears for a camper conversion, or address a vibrating driveshaft, professional help is essential. Proper gear setup requires specialized tools and exact tolerances. Don't let a failing axle leave your work van stranded. Find a driveline shop on Repairius today to keep your 2015 Ford Transit hauling smoothly for miles to come.