2023 Kenworth T680 — Transmission & Axle Gear Ratios
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Transmission gear ratios
The 2023 Kenworth T680 is a versatile truck designed for a wide range of applications, from long-haul to regional delivery. Kenworth offers a variety of transmission options from Eaton, including manual and automated manual transmissions (AMTs), each with specific gear ratios optimized for performance and fuel efficiency.
Eaton Fuller Advantage 10-Speed AMT (Automated Manual Transmission)
| Gear | Ratio |
|---|---|
| 1st | 14.40 |
| 2nd | 10.62 |
| 3rd | 7.77 |
| 4th | 5.86 |
| 5th | 4.41 |
| 6th | 3.32 |
| 7th | 2.55 |
| 8th | 1.90 |
| 9th | 1.44 |
| 10th | 1.00 |
| Reverse | 14.24 |
Eaton Fuller Advantage 12-Speed AMT (Automated Manual Transmission)
| Gear | Ratio |
|---|---|
| 1st | 16.59 |
| 2nd | 12.92 |
| 3rd | 9.94 |
| 4th | 7.74 |
| 5th | 6.06 |
| 6th | 4.70 |
| 7th | 3.65 |
| 8th | 2.84 |
| 9th | 2.22 |
| 10th | 1.72 |
| 11th | 1.34 |
| 12th | 1.00 |
| Reverse | 16.27 |
Eaton Fuller Advantage 18-Speed Manual Transmission
| Gear | Ratio |
|---|---|
| 1st (Low) | 16.41 |
| 1st | 14.11 |
| 2nd | 11.58 |
| 3rd | 8.87 |
| 4th | 6.44 |
| 5th | 4.78 |
| 6th | 3.99 |
| 7th | 3.19 |
| 8th | 2.37 |
| 9th | 1.83 |
| 10th | 1.34 |
| 11th | 1.00 |
| 12th | 0.82 |
| 13th | 0.60 |
| 14th | 0.44 |
| 15th | 0.33 |
| 16th | 0.22 |
| 17th | 0.17 |
| 18th | 0.12 |
| Reverse (Low) | 16.41 |
| Reverse | 14.11 |
Note: The 18-speed manual transmission offers a wide range of ratios for heavy-haul and vocational applications, providing excellent control and power delivery.
Available axle ratios
Kenworth offers a variety of Meritor and Dana Spicer rear axle ratios for the 2023 T680, allowing buyers to select the optimal balance between fuel economy and towing capability based on their specific needs. The availability of these ratios often depends on the chosen engine, transmission, and overall truck configuration.
| Ratio | Available With (Engine/Trim/Package) | RPO/Axle Code | Best For |
|---|---|---|---|
| 2.50 | PACCAR MX-13, Cummins X15 (Efficiency Series) | Meritor MT-40-14X, Dana D40-170 | Excellent Fuel Economy |
| 2.64 | PACCAR MX-13, Cummins X15 (Efficiency Series) | Meritor MT-40-14X, Dana D40-170 | Very Good Fuel Economy |
| 2.79 | PACCAR MX-13, Cummins X15 (Efficiency Series/Performance Series) | Meritor MT-40-14X, Dana D40-170 | Good Fuel Economy, Balanced |
| 3.08 | PACCAR MX-13, Cummins X15 (Performance Series) | Meritor RT-46-160, Dana D46-170 | Balanced Performance, Light Towing |
| 3.25 | Cummins X15 (Performance Series), Heavy Haul Packages | Meritor RT-46-160, Dana D46-170 | Good Towing, Moderate Hauling |
| 3.42 | Cummins X15 (Performance Series), Heavy Haul Packages | Meritor RT-46-160, Dana D46-170 | Strong Towing, Heavy Hauling |
| 3.55 | Vocational and Severe Service Packages | Meritor RT-50-160, Dana D50-190 | Excellent Towing, Vocational Use |
How to identify your axle ratio
Identifying the axle ratio of your Kenworth T680 is crucial for maintenance, repairs, and understanding your truck's performance characteristics. There are a few common methods to find this information:
- Door-Jamb RPO Sticker (GM style but for Kenworth): While Kenworth doesn
More specs for the 2023 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
2023 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.
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Values can vary by engine, trim and build date; check your VIN-specific service information. Updated 2026-06-22.