What is the difference between wet and dry transmissions?
3 Answers
The differences between wet and dry transmissions are as follows: 1. Different in transmission efficiency: In terms of clutch structure, the wet clutch has a more complex structure. A more complex structure means higher energy loss, resulting in lower transmission efficiency for wet dual-clutch transmissions, which occupy more engine power. With other factors remaining unchanged, this also means higher fuel consumption. 2. Response speed: The dry clutch transmits power through direct contact of metal plates, making power transmission more direct. When the metal plates are pressed tightly, the transmission ratio increases, and the effect is immediate and significant. On the other hand, the wet clutch uses oil as an "intermediary," requiring a process from the acceleration of the driving plate to the increase in oil centrifugal force, and then to the acceleration of the driven plate. This additional step results in slightly slower response speed. 3. Torque capacity: The metal friction plates of a dry clutch cannot withstand too much torque. If subjected to excessive stress impact, the friction plates can easily be damaged. Therefore, dry clutches can only be used in small-displacement, low-torque output models. In some cases, to adapt to dry clutches, certain models deliberately limit the engine's torque output in low gears to protect the transmission clutch. Wet clutches do not have such issues at all. They can handle everything from 1.5L displacement, 200N˙m family cars to 6.0L displacement, over 1000N˙m supercars, and even large diesel engines and electric motors with torque exceeding tens of thousands of N˙m, where wet clutches are commonly used.
The other day I was chatting with my neighbor about the differences between car transmissions, especially wet and dry types. Wet clutch plates are soaked in oil, like taking a bath, which provides excellent heat dissipation. They perform particularly well at high speeds or when climbing hills, with minimal overheating or stuttering, and offer high durability. That's why many automatic SUVs or high-performance cars use them nowadays. As for dry types, they rely on air cooling, with a simpler and lighter structure. They're quite fuel-efficient for everyday city driving, but in stop-and-go traffic, frequent gear shifts can lead to overheating and damage. I used to drive a manual with a dry clutch, and in summer traffic jams, the clutch would get unbearably hot, eventually requiring part replacements. Choosing which transmission depends on your driving conditions: dry is sufficient for city commuting, while wet is more reliable for frequent long-distance driving. Maintenance-wise, wet types require more frequent transmission oil changes, which is costlier, but overall, wet types win in terms of reliability.
As a car enthusiast, I particularly enjoy studying transmission details. The main difference between wet and dry types lies in the cooling method of the clutch. Wet clutches immerse the clutch plates in transmission oil, relying on the oil for heat dissipation. This provides better temperature control during mountain driving or spirited driving, reducing the likelihood of failures, and they can last up to five years without issues. Dry clutches rely solely on air cooling, offering lightweight and efficient performance ideal for daily commuting. However, stop-and-go traffic can cause them to overheat, often leading to clutch burnouts—my friend's car once required major repairs due to this. Both types are common in dual-clutch transmissions, with wet clutches handling higher torque engines, while dry clutches are used in economy cars to save space. For daily use, wet clutches are more worry-free, exhibiting fewer instances of overheating-induced vibrations and noises compared to dry clutches. Remember, driving habits play a significant role—avoid dry clutches if you engage in aggressive driving.
