NMFC Class 55 — Auto Parts
Transmissions and drivetrain components are dense, heavy parts that ship efficiently at freight class 50–55.
Typical class: 55 · Density: 35–55 lbs/cu ft
Shipment Dimensions (inches)
| Class | Density (lbs/cu ft) | Description |
|---|---|---|
| 50 | 50+ | Heaviest, most dense freight |
| 55 | 35–50 | Very dense freight |
| 60 | 30–35 | Dense freight |
| 65 | 22.5–30 | Moderately dense |
| 70 | 15–22.5 | Average density |
| 77.5 | 13.5–15 | Slightly below average |
| 85 | 12–13.5 | Below average density |
| 92.5 | 10.5–12 | Light freight |
| 100 | 9–10.5 | Light freight |
| 110 | 8–9 | Light, bulky freight |
| 125 | 7–8 | Bulky freight |
| 150 | 6–7 | Very bulky freight |
| 175 | 5–6 | Very light, bulky |
| 200 | 4–5 | Extremely light |
| 250 | 3–4 | Extremely light, high value |
| 300 | 2–3 | Low density, high handling |
| 400 | 1–2 | Very low density |
| 500 | 0–1 | Lowest density, highest cost |
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NMFC Class 55 — packaging, handling, and freight class details
Transmissions and drivetrain components — transfer cases, differentials, torque converters, driveshafts — move through similar channels as engines but with some distinct handling differences. The remanufactured transmission market is large and specialized, with companies like JASPER Engines & Transmissions and various regional rebuilders shipping cores and finished units to repair shops nationwide. The import market also generates significant volume, with new transmissions from overseas manufacturers entering through port distribution centers.
Transmission density is high — a standard automatic transmission weighs 150–250 lbs and occupies 4–6 cubic feet, yielding 35–55 lbs/cuft. This puts transmissions squarely in Class 50–55, the most economical freight classes. Multiple transmissions on a pallet increase density further. Like engines, the excellent density makes transmissions among the most cost-efficient freight to ship on a per-pound basis.
Fluid drainage is critical and non-negotiable. Transmissions contain automatic transmission fluid, transfer cases hold gear oil, and differentials hold hypoid gear lubricant — all of which must be completely drained and all ports capped or plugged before shipping. Uncapped ports allow residual fluid to drain out during transit, and even small amounts of gear oil spreading through a trailer creates serious contamination and liability issues. Carriers should visually inspect for fluid around all ports before accepting these shipments.
Machined surfaces and precision-fit components on transmissions can be damaged by improper securing. Straps must not contact valve body covers, cooling line fittings, or solenoid connectors. The proper approach is to strap through the bell housing or main case bosses. Torque converter retention is also important — some rebuilders ship with the converter installed, and if it slides out during transit it damages input shaft seals. Cores being returned for rebuilding are often less carefully packaged, so carriers should document pre-existing damage. Rate context: drivetrain freight pays well and runs consistent lanes.
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