The Truth About Dual Clutch Transmission Cars
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Date: 2019-05-28
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Comments and reviews: 9
Al Grayson
Each side of a dual clutch synchro trans doesnt have to shift as fast as the clutches shift. But whats going to happen when the synchronizers wear and get slower? Same thing as when you shift a manual transmission faster than the synchros can match the shaft and gear rpms: GRAUNCHWay back in the 1930s the Wilson preselector transmission (UK: gearbox) had some popularity. It didnt make it. The Sensaud de Lavaud continuously variable hydraulic transmission was tried. It used a variable angle swashplate pump driven by the motor crankshaft. The fluid then drove a hydraulic motor. It was inefficient and in comparison to a conventional gear transmission was large and heavy for its power capacity. Andr Citroen, head of Automobiles Citron, was fascinated by the Sensaud bite de vitesses (its only vitesses were its reverse gears) and the new Citron 7CV Traction Avant preproduction cars were equipped with the Sensaud. When demonstrated, it broke. So the production TAs had a conventional 3 speed trans. The CVT is the current attempt at having the ratio between the crankshaft and drive axles at the most efficient throttle opening-load-speed relationship. CVTs are pretty good for snowmobiles and golf cars but efficiency is not of any concern with them. Rubber V-belt CVTs are not good for automobiles as to carry the load they have to be very large. The DAF was OK for flat-as-a-pancake Netherlands but they were sorry in mountainous regions. They used two separate transmissions: one for each drive wheel. A friction drive that pressed against a flat flywheel was tried with some success but again to carry the load had to be rather large.
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Each side of a dual clutch synchro trans doesnt have to shift as fast as the clutches shift. But whats going to happen when the synchronizers wear and get slower? Same thing as when you shift a manual transmission faster than the synchros can match the shaft and gear rpms: GRAUNCHWay back in the 1930s the Wilson preselector transmission (UK: gearbox) had some popularity. It didnt make it. The Sensaud de Lavaud continuously variable hydraulic transmission was tried. It used a variable angle swashplate pump driven by the motor crankshaft. The fluid then drove a hydraulic motor. It was inefficient and in comparison to a conventional gear transmission was large and heavy for its power capacity. Andr Citroen, head of Automobiles Citron, was fascinated by the Sensaud bite de vitesses (its only vitesses were its reverse gears) and the new Citron 7CV Traction Avant preproduction cars were equipped with the Sensaud. When demonstrated, it broke. So the production TAs had a conventional 3 speed trans. The CVT is the current attempt at having the ratio between the crankshaft and drive axles at the most efficient throttle opening-load-speed relationship. CVTs are pretty good for snowmobiles and golf cars but efficiency is not of any concern with them. Rubber V-belt CVTs are not good for automobiles as to carry the load they have to be very large. The DAF was OK for flat-as-a-pancake Netherlands but they were sorry in mountainous regions. They used two separate transmissions: one for each drive wheel. A friction drive that pressed against a flat flywheel was tried with some success but again to carry the load had to be rather large.
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David Lemmo
6: 03 FCAs DDCT was introduced to the US to improve fuel economy in sedans, particularly in their compact sedan, the Dodge Dart in the absence of the 9 speed automatic that they were supposed to have in production before the model year 2013 cars were being developed. In my experience with a 2013 Dart Aero, I havent seen much difference between computer control and shifting myself. Theres times, I find that using the manual gear select if better than letting the computer shift for me. Ive found that unless Im using Electronic Speed Control (Cruise Control, the transmission computer selects a lower gear, than I would for the situation, perhaps to keep the RPMs closer to what I believe is the cars Boost Threshold. Oh, and Ive almost had to replace the damn transmission already, because it crapped out on me a couple months ago, at just under 25, 000 miles, and the garage I had the car towed to said I needed to replace the transmission. Luckily, the car still had a powertrain service contract with the dealer, so I had the car transferred to the Dealer to have them confirm the diagnosis and perform the appropriate repair. The Dealer, after making me wait a day for a slot to have the car looked at found the problem to be a loose grounding wire. Unfortunately, wiring wasnt covered and I had to pay nearly 400 after tax for a 45 minute repair of the underbody wiring, and neither was the incorrect diagnosis by the first mechanic a charge of about 50 for a half hours worth of diagnostic work, after tax, that had to be paid before they could release the car to me. Thankfully the towing was covered by AAA.
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6: 03 FCAs DDCT was introduced to the US to improve fuel economy in sedans, particularly in their compact sedan, the Dodge Dart in the absence of the 9 speed automatic that they were supposed to have in production before the model year 2013 cars were being developed. In my experience with a 2013 Dart Aero, I havent seen much difference between computer control and shifting myself. Theres times, I find that using the manual gear select if better than letting the computer shift for me. Ive found that unless Im using Electronic Speed Control (Cruise Control, the transmission computer selects a lower gear, than I would for the situation, perhaps to keep the RPMs closer to what I believe is the cars Boost Threshold. Oh, and Ive almost had to replace the damn transmission already, because it crapped out on me a couple months ago, at just under 25, 000 miles, and the garage I had the car towed to said I needed to replace the transmission. Luckily, the car still had a powertrain service contract with the dealer, so I had the car transferred to the Dealer to have them confirm the diagnosis and perform the appropriate repair. The Dealer, after making me wait a day for a slot to have the car looked at found the problem to be a loose grounding wire. Unfortunately, wiring wasnt covered and I had to pay nearly 400 after tax for a 45 minute repair of the underbody wiring, and neither was the incorrect diagnosis by the first mechanic a charge of about 50 for a half hours worth of diagnostic work, after tax, that had to be paid before they could release the car to me. Thankfully the towing was covered by AAA.
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fleur'de' win
The real problems with these Dual Clutch systems are the clutches themselves burnt out easily if you are always stuck in traffic jam in hot weather. Not only that, Volkswagen had these mechatronics failure probably got to do with the gear oil they use that shorted the electronics inside the transmission when heated up too much. Fords dual clutch transmission is built by Getrag, it is less refined than Volkswagen ones but they have the same problems. Those Dry Clutch DCT are the worst ones, shitty durability. You can find them in Volkswagen Golf TSI 1. 4L, and Ford Fiesta. Wet clutches (clutches are soaked in oil like those in motorbikes) ones are alot better but they are only found in much more expensive and powerful cars. You will find them in Golf GTI 2. 0L and VW Tiguan 1. 4L. So far only Honda manage to fix the dual clutch problems. It is mated to a hybrid car. In traffic jam situations on low speeds, the electric motor is used to creep forward instead of slipping the clutch to prevent the engine from stalling like those that pair with a conventional engine. That eliminates all the jerking motion and clutch overheating issues. Honda started using this kind of combination from the new NSX. Now Honda City and Jazz Hybrid has this kind of transmission and I never heard any failures even though my country can reach 36 Celsius on a hot day. True, it doesnt shift as fast as DCT from Volkswagen, but hey its reliable which is much more important. I buy a car to drive it everyday, not to park in a mechanics garage all the time to fix.
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The real problems with these Dual Clutch systems are the clutches themselves burnt out easily if you are always stuck in traffic jam in hot weather. Not only that, Volkswagen had these mechatronics failure probably got to do with the gear oil they use that shorted the electronics inside the transmission when heated up too much. Fords dual clutch transmission is built by Getrag, it is less refined than Volkswagen ones but they have the same problems. Those Dry Clutch DCT are the worst ones, shitty durability. You can find them in Volkswagen Golf TSI 1. 4L, and Ford Fiesta. Wet clutches (clutches are soaked in oil like those in motorbikes) ones are alot better but they are only found in much more expensive and powerful cars. You will find them in Golf GTI 2. 0L and VW Tiguan 1. 4L. So far only Honda manage to fix the dual clutch problems. It is mated to a hybrid car. In traffic jam situations on low speeds, the electric motor is used to creep forward instead of slipping the clutch to prevent the engine from stalling like those that pair with a conventional engine. That eliminates all the jerking motion and clutch overheating issues. Honda started using this kind of combination from the new NSX. Now Honda City and Jazz Hybrid has this kind of transmission and I never heard any failures even though my country can reach 36 Celsius on a hot day. True, it doesnt shift as fast as DCT from Volkswagen, but hey its reliable which is much more important. I buy a car to drive it everyday, not to park in a mechanics garage all the time to fix.
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Steven Johnson
Sequential gearboxes in rally sport arrived and they found that the gearboxes were far more reliable. Rally teams had to rebuild normal stick shift gearboxes after EACH STAGE, because drivers were slamming gears. The sequential gearboxes where not slamming gears and these gearboxes would last THE ENTIRE RALLY. So sequential gearboxes found their way into road cars. Because the gearboxes in motorsport WERE SO RELIABLE, the car manufacturers put in weak points to ensure failures. Plastic mechanical components, and poor design ensures gearbox failures around 60, 000 miles/100, 000 kilometers. A proper race sequential gearbox costs 15, 000 to 30, 000. A road going sequential gearbox cost 5000 to 10, 000 to replace, with all its engineered in weak links. There are videos on the Mitsubishi Ralliart ZF gearbox weak links. The Toyota MR2 spider also had numerous faults surrounding its systems. VW sequential gearboxes are notorious for failures. You are better off replacing your dodgey road sequential gearbox with a race sequential gearbox, itll probably outlast the car.
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Sequential gearboxes in rally sport arrived and they found that the gearboxes were far more reliable. Rally teams had to rebuild normal stick shift gearboxes after EACH STAGE, because drivers were slamming gears. The sequential gearboxes where not slamming gears and these gearboxes would last THE ENTIRE RALLY. So sequential gearboxes found their way into road cars. Because the gearboxes in motorsport WERE SO RELIABLE, the car manufacturers put in weak points to ensure failures. Plastic mechanical components, and poor design ensures gearbox failures around 60, 000 miles/100, 000 kilometers. A proper race sequential gearbox costs 15, 000 to 30, 000. A road going sequential gearbox cost 5000 to 10, 000 to replace, with all its engineered in weak links. There are videos on the Mitsubishi Ralliart ZF gearbox weak links. The Toyota MR2 spider also had numerous faults surrounding its systems. VW sequential gearboxes are notorious for failures. You are better off replacing your dodgey road sequential gearbox with a race sequential gearbox, itll probably outlast the car.
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Jeffery Surratt
I agree with Scotty 99. 9 % of the time but, I own a 2006 VW Jetta with 150, 000 miles and zero problems with the dual clutch transmission. The transmission must be serviced with new oil and filter every 40, 000 miles. How many owners fail to do this and then wonder why the transmission fails at 100, 000 miles? I learned to work on cars from my father a mechanic / collision repairman. Preventive maintenance is the key to long life, when it comes to cars and most owners never follow even the basic recommendations in the owners manual. Hell, most do not even read their owners manual. Many car repairs today cost so much that a transmission or engine repair exceeds the value of the car, just use the money to buy another used car with less than 60, 000 miles and you will never have to pay for a major repair.
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I agree with Scotty 99. 9 % of the time but, I own a 2006 VW Jetta with 150, 000 miles and zero problems with the dual clutch transmission. The transmission must be serviced with new oil and filter every 40, 000 miles. How many owners fail to do this and then wonder why the transmission fails at 100, 000 miles? I learned to work on cars from my father a mechanic / collision repairman. Preventive maintenance is the key to long life, when it comes to cars and most owners never follow even the basic recommendations in the owners manual. Hell, most do not even read their owners manual. Many car repairs today cost so much that a transmission or engine repair exceeds the value of the car, just use the money to buy another used car with less than 60, 000 miles and you will never have to pay for a major repair.
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Kraig
You missed the biggest problem with these transmissions, and that is creeping at stop lights and such. People are used to torque converter transmissions where they can just take their foot off the brake a bit and creep forward. They do this all the time. With a dual clutch transmission, this wears the clutch each time, and because people are used to creeping forward in automatic transmissions, they usually wear out the first clutch on these transmissions pretty quickly. Then the cars start shuddering as you take off from a start. Like you said, a completely unnecessary transmission for the everyday driver.
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You missed the biggest problem with these transmissions, and that is creeping at stop lights and such. People are used to torque converter transmissions where they can just take their foot off the brake a bit and creep forward. They do this all the time. With a dual clutch transmission, this wears the clutch each time, and because people are used to creeping forward in automatic transmissions, they usually wear out the first clutch on these transmissions pretty quickly. Then the cars start shuddering as you take off from a start. Like you said, a completely unnecessary transmission for the everyday driver.
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yang miao
I own a 2010 Porsche panamera with PDK(German way of saying DCT) Transmission, bought it used didnt pay much. Now it has 140k km on it, No major complain about that transmission, Clutch engagement is weird in reverse. Jerky shift in first gear. Test drived new Panamera with newer PDK, Feels more or less the same. Scotty was right, DCT is not design for everyday drive. But on the other hand, I think Wet Clutch DCT would last very long time, at least way longer than dry clutch DCT since the clutch pack is cooled and lubercated by ATF. finger crossed on my Porsche Scotty Kilmer
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I own a 2010 Porsche panamera with PDK(German way of saying DCT) Transmission, bought it used didnt pay much. Now it has 140k km on it, No major complain about that transmission, Clutch engagement is weird in reverse. Jerky shift in first gear. Test drived new Panamera with newer PDK, Feels more or less the same. Scotty was right, DCT is not design for everyday drive. But on the other hand, I think Wet Clutch DCT would last very long time, at least way longer than dry clutch DCT since the clutch pack is cooled and lubercated by ATF. finger crossed on my Porsche Scotty Kilmer
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James Palermo
My GTI has a DSG. Its fun as hell to have relentless uninterrupted acceleration, launch control, and perfect downshifts. That said I wouldnt want my mother driving one because you need to treat them like a manual (dont creep in traffic, reverse is weird, etc) and they make no sense if you dont drive hard enough to care about a seamless shift. It is nice to have the excitement and feel of a clutch based tranny combined with the comfort of an auto when you just wanna get home though. I can afford the expense and its fun. IMO Life is short, have fun. :)
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My GTI has a DSG. Its fun as hell to have relentless uninterrupted acceleration, launch control, and perfect downshifts. That said I wouldnt want my mother driving one because you need to treat them like a manual (dont creep in traffic, reverse is weird, etc) and they make no sense if you dont drive hard enough to care about a seamless shift. It is nice to have the excitement and feel of a clutch based tranny combined with the comfort of an auto when you just wanna get home though. I can afford the expense and its fun. IMO Life is short, have fun. :)
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001Rupes
Scotty Kilmer The real advantage of paddle shifters is that it allows you to downshift before you actually hit the accelerator, to be at maximum power rpm. You never need it on highways, but on those windy country roads with very limited passing opportunities, where waiting for the car to downshift eats up precious space. They also allow you to keep the balance of the car in sweeping corners where an unwanted upshift could upset the balance. Commuters will not understand. Drivers will. Im happy that the manufacturers consider drivers with these features.
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Scotty Kilmer The real advantage of paddle shifters is that it allows you to downshift before you actually hit the accelerator, to be at maximum power rpm. You never need it on highways, but on those windy country roads with very limited passing opportunities, where waiting for the car to downshift eats up precious space. They also allow you to keep the balance of the car in sweeping corners where an unwanted upshift could upset the balance. Commuters will not understand. Drivers will. Im happy that the manufacturers consider drivers with these features.
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