When it comes to transmission types for performance vehicles, dual clutch transmissions and manual transmissions are two of the most popular options. Both transmission types have their own advantages and disadvantages when it comes to speed and performance. In this article, we’ll compare dual clutch transmissions and manual transmissions to determine which one is ultimately faster on the track.
How Dual Clutch Transmissions Work
A dual clutch transmission (DCT), sometimes called a twin-clutch transmission, uses two separate clutches for odd and even gears. This allows the transmission to shift between gears much faster than a traditional manual or automatic transmission.
In a dual clutch transmission, two input shafts each have their own clutch. One clutch controls the odd numbered gears (1st, 3rd, 5th, etc.) while the other controls the even gears (2nd, 4th, 6th, etc.). This allows the next gear to be pre-selected on one input shaft while the other clutch remains engaged with the current gear.
When shifting to the next gear, the transmission computer quickly disengages one clutch and engages the other clutch. This swap happens in just a few milliseconds, much faster than the shift time in a manual transmission. The dual clutches allow for uninterrupted power delivery during shifts, keeping acceleration smooth.
Benefits of Dual Clutch Transmissions
Here are some of the key benefits of dual clutch transmissions:
- Faster shift times – DCTs can shift gears in just 100-150 milliseconds, much faster than a manual.
- Better acceleration – DCTs have uninterrupted power delivery during shifts for better acceleration.
- Improved fuel economy – DCTs are more fuel efficient than traditional automatics.
- Paddle shifting – Some DCTs allow the driver to manually shift gears using paddle shifters.
- Less driver input – DCTs automatically shift instead of requiring clutch pedal input.
How Manual Transmissions Work
Manual transmissions have been around for decades and are still popular in many sports cars and racing vehicles. In a manual transmission, the driver uses a clutch pedal to manually shift gears.
When the clutch pedal is pressed in, it disconnects the engine from the transmission to allow the driver to shift into a different gear pair. Once the new gear is selected with the shifter, the driver slowly releases the clutch pedal to engage the engine and transmission.
Manual transmissions give drivers total control over gear shifts. But shift times are much slower than dual clutch transmissions, generally between 400-800 milliseconds for experienced drivers. Releasing the clutch pedal smoothly takes practice and skill.
Benefits of Manual Transmissions
Here are some of the key benefits of manual transmissions:
- Driver control – Manuals allow the driver to fully control gear shifts.
- Weight savings – Manuals weigh less than automatics and DCTs.
- Cost savings – Manuals cost less to manufacture than complex automatics.
- Mechanical feel – Manuals offer an engaging, mechanical driving experience.
- Racing heritage – Almost all purpose-built race cars use manual transmissions.
Dual Clutch vs. Manual: Shift Speed
When it comes to determining which transmission shifts faster, the dual clutch transmission has a clear advantage. Let’s compare some actual shift time numbers:
| Transmission Type | Typical Shift Time |
|---|---|
| Dual clutch transmission | 100-150 ms |
| Manual transmission | 400-800 ms |
As you can see from the data, a DCT can shift gears over twice as fast as a manual transmission. The dual clutch design allows for lightning-fast shifts when accelerating or decelerating. Manual transmissions cannot physically shift gears as quickly due to the mechanical limitations of manual clutches and shifters.
Real World Shift Speed Comparison
Various automotive publications have tested the 0-60 mph acceleration times of sports cars with DCTs versus similar cars with manual transmissions. The increased shift speed of the DCTs allows them to accelerate to 60 mph faster:
| Vehicle | Transmission | 0-60 mph Time |
|---|---|---|
| Ferrari 458 | 7-speed dual clutch | 3.3 seconds |
| Ferrari 458 | 6-speed manual | 3.6 seconds |
| Porsche 911 GT3 | 7-speed dual clutch | 3.2 seconds |
| Porsche 911 GT3 | 6-speed manual | 3.8 seconds |
The performance numbers clearly show the acceleration advantage of dual clutch transmissions over manuals, thanks largely to their faster shift speeds.
Reliability: Dual Clutch vs. Manual
When it comes to reliability, manuals pull ahead of dual clutch transmissions. Manual transmissions use fairly simple mechanical gears and synchronizers that are durable and time-tested.
Dual clutch transmissions are more technologically complex, with advanced electronics and hydraulic systems controlling the two clutches and gear shafts. This introduces more potential points of failure. Some manufacturers have had issues with DCT reliability and longevity, especially in the first generation of mass-produced units.
That being said, dual clutch technology has improved in recent years as automakers continue honing the design. Modern DCT units are generally very reliable when properly maintained, on par with automatic transmissions.
Maintenance and Repair Cost
Manual transmissions are generally the least expensive transmission type to repair and maintain. The mechanical components like clutches and synchronizers are relatively inexpensive to replace when needed.
Dual clutch transmissions use two clutches and complex electronics, so repair costs are significantly higher when things go wrong. The clutch actuators, control modules, and solenoids can fail and be quite costly to replace.
Tuning Potential
For drivers modifying their vehicles for more power, manual transmissions are easier to upgrade and tune than DCTs. Clutches, flywheels, and other components can be swapped in a manual to handle more torque. Manuals can also be fun to tune by adjusting the shifter mechanisms and changing shift knobs.
Tuning DCTs for higher performance is very difficult and impractical for the average owner. TheOEM transmission tuning is already highly optimized from the factory. Aftermarket companies do not offer DCT tuning kits like they do for manuals. For serious tuning, a manual still provides the most flexibility.
Driver Engagement
Many driving enthusiasts prefer the increased engagement and control that comes from using a manual transmission. Heel-toe downshifting, perfectly rev-matched shifts, and using the clutch to initiate slip angles when drifting are just a few examples of engaging manual techniques.
While some high-end DCTs offer paddle shifters for manual control, they still cannot quite match the feel and involvement of driving a car with a true manual gearbox. The hands-on experience of managing the clutch, shifter, and engine revs in a manual heightens the sensation of control.
Common Myths About Dual Clutch vs. Manual
There are also some common myths and misconceptions when comparing DCTs and manual transmissions. Here are a few:
Myth: Dual clutches overheat easily
Reality: In the early days of dual clutch transmissions, some models like Volkswagen’s DSG had issues with clutch overheating. But modern DCTs use improved clutch materials and cooling systems that very rarely overheat, even under race conditions.
Myth: Manuals get better fuel economy
Reality: This used to be true decades ago when automatics were inefficient. But modern DCTs and automatics can match or exceed the fuel efficiency of manuals thanks to advancements like lock-up torque converters and low viscosity transmission fluid.
Myth: Dual clutches are only for high-end sports cars
Reality: While DCTs debuted on expensive supercars, they are now common on affordable mainstream cars. Ford, Honda, Hyundai, and Chevrolet all offer dual clutch options on models like the Focus, Civic, Elantra, and Cruze.
Myth: Manuals are lighter weight
Reality: It’s true that manuals are simpler mechanically than DCTs. However, a lot of the weight difference comes down to packaging. Some manual transmissions are integrated with the rear differential, adding weight. Packaging differences make comparisons difficult.
Conclusion
In summary, dual clutch transmissions provide faster shift speeds and acceleration performance compared to manual transmissions. But manuals offer lower cost, easier repairs, tuning potential, and a more engaging driving experience preferred by many enthusiasts.
For race car drivers and amateur competitors seeking the fastest lap times, a dual clutch transmission is the ideal choice. But manuals are still preferred for affordable sports cars focused more on the experience than lap times.
Dual clutches tend to be standard on exotic supercars where customers expect cutting edge performance. Manuals remain an option on sports cars catering to purists, such as the Mazda Miata, Nissan 370Z, and Toyota 86.
The right transmission choice ultimately depends on the vehicle, use case, and priorities for the owner. There is no definitive answer on whether dual clutch or manual is better across the board. For some, shift speed trumps all else. For others, the engagement of rowing the gears is irreplaceable.