What Causes the Clicking Sound in a Dual-Clutch Transmission?
3 Answers
Dual-clutch transmissions produce clicking sounds due to their inherent structural design. The relevant explanations are as follows: 1. The basic structure of a dual-clutch transmission is similar to that of a manual transmission, both utilizing gear-driven mechanisms. 2. The key difference lies in the fact that a dual-clutch transmission is equipped with two clutches, each independently connected to a set of gears controlling odd-numbered and even-numbered gears respectively. 3. When the hydraulic servo system of the clutch or the transmission control unit fails to precisely manage gear disengagement and engagement, abnormal noises and jerking may occur. The advantages of dual-clutch transmissions include: 1. Short shift times. 2. Improved fuel efficiency. Since there is no torque interruption in dual-clutch transmissions, the engine's power is continuously utilized, resulting in lower fuel consumption compared to conventional automatic transmissions. 3. Minimal power loss during transmission. During gear shifts, torque loss is almost negligible, enabling extremely fast upshifting.
I've driven a dual-clutch car for six years, so I'm all too familiar with that clunking sound. It's most noticeable during low-speed traffic, like the sound of metal plates rubbing against each other. Once during maintenance, the technician told me it's a common issue with dual-clutch transmissions, especially dry dual-clutch types. When the two clutches alternate, improper gear engagement causes that clunking noise. It's particularly obvious in stop-and-go traffic with frequent shifts between 1st and 2nd gears. If you hear metal clanging sounds right after startup, it might be an issue with the clutch fork. In such cases, I always check the transmission fluid first – deteriorated fluid leads to insufficient lubrication. Problems with shift logic can also cause this, and a software update at the dealership can help. For older cars, it's often due to excessive clutch disc wear, meaning they need replacement.
Having worked on transmissions for ten years, I've encountered quite a few such abnormal noises. The clicking sounds in dual-clutch transmissions mostly come from gear collisions inside the gearbox. Occasional slight noises during normal driving are fine, but if accompanied by jerking and power interruption, be cautious. The most common issue is clutch actuator failure, especially when the hydraulic control unit loses pressure. Next is dual-mass flywheel damage, which sounds like hitting a metal sheet. Some owners report noises right after clutch assembly replacement, often due to improper adjustment of assembly clearance. It's recommended to check transmission oil pressure data with a diagnostic tool and note the RPM range where the noise occurs. Dry dual-clutch transmissions are more prone to this issue than wet ones due to the lack of oil cushioning.
