What is the Difference Between Dry and Wet Dual Clutch?
2 Answers
The biggest difference between dry and wet dual clutches lies in the connection medium between the driving and driven plates. The dry dual clutch relies on air for transmission, while the wet dual clutch uses oil. However, their working principles are largely the same, with both utilizing two sets of clutches operating simultaneously—one managing odd-numbered gears and the other handling even-numbered gears. Dry Clutch: A manual transmission friction plate clutch with low manufacturing cost and high mechanical transmission efficiency. The downside is that operation requires mastering specific techniques, can be cumbersome, and has a higher failure rate. Wet Clutch: An automatic transmission oil-immersed friction plate clutch, which requires the design of a hydraulic coupling or torque converter for flexible power connection. It has a higher manufacturing cost and lower mechanical transmission efficiency. The advantage is easier operation and a lower failure rate. The wet dual clutch transmission must include a hydraulic pump, lubricating fluid, cooling pipes, and an external cooling system. In contrast, the dry dual clutch, by eliminating these hydraulic systems, offers advantages in manufacturing cost, weight reduction, and space optimization. Additionally, without hydraulic resistance, the dry dual clutch achieves higher transmission efficiency and better fuel economy compared to the wet type. During operation, dual clutch transmissions generate heat through friction, especially in stop-and-go traffic, necessitating cooling to ensure normal functioning. The dry dual clutch relies on air cooling for heat dissipation, while the wet type, being oil-immersed, has significantly higher cooling efficiency. This makes the dry type more prone to failure, as evidenced by the widespread criticism of Volkswagen's 7-speed dry dual clutch. Usage Recommendations: Dual clutch transmissions are not suited for frequent starts, prolonged low-speed driving, or stop-and-go traffic, as these conditions can lead to overheating and potential failures. If the vehicle's computer issues a warning, it is essential to stop immediately and cool the transmission. When stuck in unavoidable traffic, try to use lower gears (including manual or S mode) to follow the flow. This can significantly reduce excessive clutch heat caused by constant gear shifting.
I've been driving for over a decade and have tried many dual-clutch transmissions. The dry dual-clutch is characterized by being lightweight and efficient, making it suitable for daily city driving; the clutch plates operate dry without needing oil, which makes the car fuel-efficient and saves space—very practical, especially common in compact cars. However, its downside is poor heat dissipation. During traffic jams or uphill driving, friction heat accumulates too quickly, easily leading to overheating warnings or even failures, which can be expensive to repair. As for the wet dual-clutch, the clutch plates are immersed in oil, which helps with heat dissipation and lubrication, making high-speed driving smoother with faster shifts and less jerkiness. However, it is generally heavier, increasing fuel consumption. For regular household use, the dry type is recommended for cost savings and simplicity, but for long-distance or frequent full-load driving, the wet type is more reliable. Additionally, the dry type tends to have more issues in humid or high-temperature areas, so it's advisable to avoid frequent stop-and-go driving to protect it.
