2024 Kenworth T680 Transmission & Axle Gear Ratios
Comprehensive guide to gear ratios in the 2024 Kenworth T680 for optimal performance and efficiency.
Working on this 2024 Kenworth T680? Run just this one job through Repairius.
No big switch. Write the estimate, text it for approval, and get paid on your phone. Keep everything else the way it is.
14-day free trial · credit card required · cancel anytime
Transmission gear ratios
The 2024 Kenworth T680 offers a variety of transmission options to suit different applications, from long-haul efficiency to heavy-duty hauling. The most common transmissions are automated manual transmissions (AMTs) from PACCAR (TX-12, TX-18) and Eaton (Endurant, UltraShift Plus), as well as a range of manual transmissions.
PACCAR TX-12 Automated Manual Transmission
The PACCAR TX-12 is a 12-speed automated manual transmission designed for fuel efficiency in line-haul applications.
| Gear | Ratio |
|---|---|
| 1st | 16.88 |
| 2nd | 12.90 |
| 3rd | 9.87 |
| 4th | 7.57 |
| 5th | 5.86 |
| 6th | 4.54 |
| 7th | 3.51 |
| 8th | 2.70 |
| 9th | 2.08 |
| 10th | 1.62 |
| 11th | 1.25 |
| 12th | 0.97 |
| Reverse | 17.50 |
PACCAR TX-18 Automated Manual Transmission
The PACCAR TX-18 is an 18-speed automated manual transmission, offering more versatility for demanding applications with higher GVW and GCW.
| Gear | Ratio |
|---|---|
| 1st | 16.86 |
| 2nd | 14.15 |
| 3rd | 11.83 |
| 4th | 9.92 |
| 5th | 8.30 |
| 6th | 6.96 |
| 7th | 5.82 |
| 8th | 4.87 |
| 9th | 4.08 |
| 10th | 3.42 |
| 11th | 2.86 |
| 12th | 2.40 |
| 13th | 2.01 |
| 14th | 1.68 |
| 15th | 1.41 |
| 16th | 1.18 |
| 17th | 1.00 |
| 18th | 0.84 |
| Reverse | 17.65 |
Eaton Endurant XD/XD Pro Automated Manual Transmission
Eaton's Endurant series, particularly the XD and XD Pro, are popular choices for their efficiency and performance.
| Gear | Ratio |
|---|---|
| 1st | 14.40 |
| 2nd | 11.23 |
| 3rd | 8.75 |
| 4th | 6.82 |
| 5th | 5.31 |
| 6th | 4.14 |
| 7th | 3.22 |
| 8th | 2.51 |
| 9th | 1.95 |
| 10th | 1.52 |
| 11th | 1.18 |
| 12th | 0.92 |
| Reverse | 15.00 |
Available axle ratios
The 2024 Kenworth T680 offers a wide range of axle ratios to optimize for specific operational needs, balancing between fuel efficiency and pulling power.
| Ratio | Available With (Engine/Trim/Package) | RPO/Axle Code | Best For |
|---|---|---|---|
| 2.26 | PACCAR MX-13, MX-11 (Efficiency Packages) | Often indicated on build sheet | Best for maximum fuel economy, light loads, flat terrain |
| 2.47 | PACCAR MX-13, MX-11 (Standard/Efficiency) | Often indicated on build sheet | Excellent fuel economy, general freight, moderate terrain |
| 2.64 | PACCAR MX-13, MX-11 (Balanced Packages) | Often indicated on build sheet | Good balance of fuel economy and performance |
| 2.79 | Cummins X15 (Efficiency Series) | Often indicated on build sheet | Balanced performance, versatile for various applications |
| 3.08 | Cummins X15 (Performance & Vocational) | Often indicated on build sheet | Better pulling power, moderate grades, heavier loads |
| 3.25 | Cummins X15 (Vocational/Heavy Haul) | Often indicated on build sheet | Strong pulling power, hilly terrain, construction/vocational |
| 3.42 | Cummins X15 (Heavy Haul/Specialty) | Often indicated on build sheet | Maximum pulling power, severe grades, heavy equipment transport |
How to identify your axle ratio
Identifying the axle ratio in your 2024 Kenworth T680 is crucial for maintenance, repairs, and understanding your truck's capabilities. Unlike some passenger vehicles, commercial trucks often have the axle ratio clearly listed on the build sheet or line-setting ticket, which should be with the vehicle's documentation.
For Kenworth trucks, the most reliable way to find your axle ratio is to consult the manufacturer's data plate or sticker, usually located on the driver's side door jamb or inside the glove compartment. This sticker will contain a wealth of information, including the Vehicle Identification Number (VIN), gross vehicle weight ratings (GVWR), and often, a series of codes related to axles and other drivetrain components. Look for an "Axle Code" or "Ratio" entry. You may need to cross-reference this code with a Kenworth parts catalog or contact a dealership with your VIN to fully decipher it.
Another method, although less common for newer trucks, is to check for an axle tag on the differential housing itself. This metal tag, if present, will typically be bolted to the differential cover and will have the axle ratio stamped on it. Be aware that this tag can be difficult to read due to grime, rust, or damage.
Finally, a VIN decoder service can sometimes provide axle ratio information, especially if it
More specs for the 2024 Kenworth T680
Oil Capacity & Filter
Capacity, weight, filter PN, drain plug torque, change interval.
Fluid Type Specs
Engine oil, coolant, ATF, diff, brake, PS, DEF — with OEM spec numbers.
Coolant Capacity & Type
Total system capacity, OEM coolant spec, flush interval, bleed tips.
Transmission Fluid & Service
Trans model, fluid spec, capacity, filter PN, service interval.
Torque Specifications
Lug nuts, drain plug, caliper, axle nut, plug, key fasteners.
Brake Pad & Rotor Specs
Pad PNs, rotor size, min thickness, caliper torque.
Tire Size & Pressure
OEM size, cold psi, bolt pattern, wheel size, TPMS.
Battery Size & Group
Group size, CCA, AGM/flooded, dimensions, reset note.
A/C Refrigerant & Oil
R-134a or R-1234yf, charge oz, PAG oil spec.
Bulb Sizes (Headlight, Tail, Fog)
Headlight, fog, tail, turn, reverse, interior.
Factory Maintenance Schedule
Service intervals by mileage, severe-duty notes, known issues.
Towing Capacity & Payload
Max tow, payload, GVWR/GCWR, hitch class by trim.
Fuse Box Diagram & Amperage
Fuse box locations, layout, amps, and what each fuse controls.
Serpentine Belt Routing & Length
Belt routing, length, rib count, OEM + aftermarket PNs.
Wheel Alignment Specifications
Camber, caster, toe ranges (front & rear), adjustability notes.
Paint Color Codes
All factory colors with paint codes, sticker location, touch-up tips.
Wiper Blade Sizes
Driver/passenger/rear blade size, attachment, OEM + cross-refs.
Spark Plug Type & Gap
Plug PN, gap, torque, interval by engine.
Key Fob Programming
DIY programming steps, FCC ID, fob PN, battery, transponder.
Same spec — other model years
Maintenance & repair guides
2024 Kenworth T680 Maintenance Schedule →
Available maintenance guidance; confirm the manufacturer schedule.
Repair planning references →
Plan the scope of work; detailed procedures need configuration-matched evidence.
Browse by make
Running an auto or diesel repair shop?
Compare Repairius to the shop software you're paying for
$99.99/month (first location included), unlimited users, 14-day free trial.
Values can vary by engine, trim and build date; check your VIN-specific service information. Updated 2026-06-26.