How a Dual Clutch Transmission Works
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- Опубликовано: 30 окт 2022
- Here is a look at what’s inside a dual clutch automatic transmission and how it works!
A dual clutch transmission is internally very similar to a manual transmission - with the exception that the computer (mechatronic unit) is responsible for physically shifting the gears. Instead of a single dry clutch like in a manual transmission, a DCT uses two wet clutches, one larger than the other one to drive two input shafts to the transmission. The two input shafts will power either the even gears or odd gears.
Other accessories to the transmission include a transmission cooler, oil filter and oil pump that serves to cool and lubricate gears and bearings. The transmission computer is located inside the transmission mechatronic unit, which control solenoids to redirect fluid flow through a valve body. The valve body will in turn feed transmission fluid through the housing and into the pistons which will control the position of the selector forks and thus select the gear.
One advantage of a DCT is that it can shift gears much faster by preselecting the next gear that the computer thinks it will shift to. It does this by engaging the fork of the opposing gear that is currently being used. The downside is that it can often get confused if the driver has erratic inputs and therefore cause hesitation or jerky output.
Finally, while the wet clutch and gear synchronizers are often wear points on these transmissions, the mechatronic unit is often the fault for many failures.
The transmission in this video is a DSG (direct shift gearbox) D250 unit from a 2006 Volkswagen Jetta TDI.
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I still continue to be highly impressed with your knowledge on cars. You're like a neurosurgeon working on cars. UNBELIEVABLE. Like a walking encyclopedia. Good for you!
I often watch videos at 1.75x speed but yours I was able to watch at 1x. Great editing and no time wasting 👍
Glad you like the speed, I thought it was too slow
@@speedkar99 The speed is just right for me, I still needed to pause and go backwards a couple of times.
As a junior (thermal/aero) enginner in the automotive, I consider these videos pure GOLD! You would not believe how much stuff we learn in school, and even on the job, but especially now with electric vehicles everyone specialises on just a tiny parts/systems of the car. Seeing this stuff is so interesting, and it allows through your eyes and experience to have the general view of all the systems! Plus now, a lot of these mechanical parts will be gone with EV, so I try to learn what I can before they disappear completely! Thank you!
Glad you learned alot. I too didn't learn any of this in engineering school
Great vid, as usual. Those clutch pads are in mint condition given the fact that the vehicle drove over 300 kkm. Looks to me like a great piece of engineering.
Sure is quite the engineering.
However I have no history on the car if these clutches were changed before....
@@speedkar99 You're right, I didn't think about it - it could've been replaced at some point.
@@dehypnotizer I've got a manual v dub. This DSG tranny cost over $300 to service. The manual was $50. Though some things are engineered well, others like the plastic water pump.....not so much. I've got a Japanese car for EVERYTIME something breaks on my v dub.
@@easley421 What failed in your transmission? I have a DCT and it seems to be quite robust (2nd car, no service, except oil changes, required).
@@dehypnotizer Nothing failed in my tranny. It's a six speed manual, BULLETPROOF. What I was saying was the service for the transmissions were vastly different. The DSG first service 300$, my manual $50.
I have a 2013 Volkswagen CC. So far I've had to change the water pump, the fuel control module on top of the fuel pump, rewire the wires connected to the trunk lid because they crease and cause the car to become possessed when the wires touch. I'm not even joking, my girl put it in reverse one morning and the trunk popped. I go up in there and pull the wiring harness out and they're all frayed to shit. There's been a few other incidents with this car, all the while my 2006 G35 remains running, without an issue.
My buddy is a mechanic and sent me a pic of a new Dodge Ram tranny filter change. The entire pan of the tranny.......PLASTIC! With the filter BUILT IN. This shits not gonna get better. Hold on to anything between 2001-2009. The best years for cars and bike IMO
Literally blown away. The machining to make it all work is only matched by your explanation. Thanks for all the effort to teach me why bicycles still have a place in this world (maybe horses too). Your #1. Still do not understand how you can sit cross legged based on the Mrs. cooking. You two are real stars of youtube!
Ah, the dreaded oil pump drive. It broke on my wife's 2008 Passat, a common major failure which VW wouldn't acknowledge. I had bought VWs all my life until that event, but VW just threw us in the ditch, customer loyalty meant nothing, so I now have a nice Volvo. Nice to see the gearbox tear down, makes you realise how much things have moved on since the days of the Morris Minor with no synchro on 1st gear....Thanks for posting, love the high speed explanation of dual clutch transmission, the concentric clutches seems a nice idea.
Glad you liked it and learned something new
Wanted a DCT video for a while now. Great video as always.
That bit you said about the transmission becoming "confused." This is exactly the problem I have with modern car technology. The transmission itself is fascinating, and in theory, a great idea. But making it so complex that it cannot function, is a bad idea. I can't imagine a Turbo-Hydramatic becoming "confused." Great video, and as always, I love your choice of rags to clean up with.
Yeah unfortunately the nature of DCT's being able to shift quickly relies on alot of computer input. As algorithms get better that should be ironed out.
a late turbo-hydramatic has a whooping count of...4...gears that are wide and torque converter lockup came around in the 90s. If you're fine with the garbage gas mileage, then sure, keep the "unconfuseable" dinosaur which shifts at glacial speeds.
If you want a smaller, lighter and substantially more efficient auto gearbox, you need a computer. Or a manual transmission...
GREAT video, I had no idea how these worked. The condition of the clutch disks is amazing. Great design. Thank you.
You are welcome! I didn't know much myself until tearing this down and researching
makes you appreciate the simplicity of a manual transmission
Transmission's always make my brain hurt, but I think this is the first time I feel like I've understood something about their mechanicals.
These are very valuable spare parts. Hope they get to work again some day.
Absolutely love your videos very educational and hilarious I appreciate all you do. Watching your videos is so easy because your not afraid to show your process of figuring it out when others cut that out and try to look like they know it all and don't make mistakes. Keep it up I look forward to all your videos
I'm glad you like them, feedback encourages me alot. For me, the process is if it doesn't come out, then the angle grinder will take it out haha
Oh, excellent breakdown. I like the way you explained the gear selections but unfortunately you lost me between gears and splines. Good thing no exams at the end. :-)
Wow I can’t lie I was expecting all the parts to be worn and in poor condition, glad to see VW manufactured a (mechanically) reliable unit.
I personally find that people give VW a bad rep. All you need for your VW product to be reliable is treat it kindly. But that’s just my opinion.
@@dragonofyorha well to be fair VW cars have been known to have electronic issues and become expensive to maintain once they reach a certain point down the road.
Nope, it's quality is not very good
The newer gen. of DSG are More reliable than the first one. The first gen. was crap
@@PDD87 less worse, you mean....
He has a dry sense of humor. Love it.
Glad you get it 😏
Great video. Understood everything ...except ... how could anyone invent this!!! Pure genius. Nobel prize material!
It sure is genius. But not very popular as the Mechatronics unit typically goes on these
Your knowledge on mechanical theory is definitely A+ thank you for this video you kept me tuned in from start to finish 🙏
Excellent video as usual, please keep coming, thank you!
Thank you very much publisher for this beautiful lesson and demonstration .
Love the toothbrush… this some of the best content on RUclips!
Glad you appreciate it
Amazing work my friend. Thanks so much for this.
The complexity of this gearbox is mindboggling.
No wonder nobody wants to touch these.
I had the un-pleasure of driving a car with single clutch robotic, and if this one shifts as slow as the one I had (the actual movement of the forks, not the clutch engagement), no wonder the internals are that well preserved.
DSG are one of the faster shifting transmissions. A single clutch would take a much longer time to shift
Great video! Love the way you explain how things work
Thanks!
Your appropriately used fast speed is wonderful. I wish everyone used it in their videos.
I'm glad you like the pace. Sometimes I think I'm too slow
Amazing video as usual, thank you for putting out straight knowledge, you’ve taught me a lot so far
I'm very thankful for what I've learned from this man.
Fantastic video! You are a Very smart man! Thank you for spreading your knowledge with everyone on here! I really enjoy your humor!
I'm glad you like it 🙂
Incredible video. The editing was great, explainations were simple, and your snap ring tool made me giddy.
I'll always sub to this kind of AAA content.
That preselecting explanation is the best i have heard, wonder why triple clutch transmissions are not a thing, it would have major benefits to be able to preselect a gear above and a gear below so it's always ready with zero hesitation i would think...
Great video, thanks for the information and knowledge.
Transmissions are so cool - thanks SpeedKar
While looking very complex amazing it works as seamless as it does. Been driving manual transmission cars for long time but recently purchased a 2022 VW Arteon that has the wet clutch 7 speed DSG. Hope it is as dependable as standard manual transmission. Thanks for posting the interesting and elucidating video!
I'm not sure about VW's recent DSG but the older ones had issues with the Mechatronic unit
@@speedkar99 Thank you for your input!
I wish I had your snap ring removal tool when I was replacing my steering lock last week!
Great explanation without the "mandatory" 25 minutes of "filler content" to make the video longer
Thanks for another informative video. Your snap ring removal tool really gets the job done. Maybe you can sell it under the Snap-Off brand.
Nice video. Lot of engineering went into designing and manufacturing of this transmission, I am impressed. I drove a Porsche Boxster with a DCT, it was a very good unit, crisp/fast/precise. But I personally prefer manual transmissions.
Yes the shifts are very fast, and that's the main advantage here over the manual.
At some point I need to get better clutch plates etc for my dual clutch BMW. Good to see even regular clutches in various cars are strong.
What happened, is your dct clutches going bad?
VW DSGs have a repuration of lasting either 300000 kilometres, or 10, as has happened to many earlier customers…
Fantastic video and explanation. One of the best I've seen👋👋👋👋👋
Your videos are put a smile on my face every time!!! Keep it up ;)
I'm glad you appreciate it
It's hard to describe the feel of a DSG transmission to someone who's used to regular automatics, so great job doing that in your vid!
My MK6 GTI has the DSG and I love how lightning quick the shifts are. My only dislike is getting going from a full stop, as it can be a bit rough. I've learned to just give it more gas than you'd think as opposed to easing on the gas pedal to try to gently roll off the line.
I agree, the first time I drove this car (MK5 Jetta) I was surprised at how fast it shifted. It also short shifted but then again it was a diesel
Still not as direct as a conventional MT, but it's a nice compromise between AT and MT
As a software engineer I have no idea what he is talking about, but I think that transmissions are made with magic
As a mechanical engineer I have no idea how computers work. I think they're made with magic
Special snap ring tool definitely gets a thumbs up
Well thanks!
@@speedkar99 yes sir. I very much enjoy watching you tear things down and explain them. Your videos are great and always entertaining and educational
@@speedkar99 A well deserved "Thumbs Up", I must interject. I absolutely LOVE your channel. I wish YT would have shown it to me years sooner. Your dry sense of humor, coupled with your incredible knowledge, is a winning combination, at least in my opinion! Thank You for all the effort that you clearly put into making these videos, which definitely make me and I am sure a few others, just a bit smarter! You ROCK!
THANKS FOR THE GREAT EXPLANATION
Welcome
Great description
Thanks
Thanks for the useful material!
You are welcome!
I so love it if someone exactly knows how things work!
Awesome video!
Great video as usual
Awesome video!! So informative! No torque convertor is really not a good idea in an automatic, will not get a DCT car ever
Thanks.
The concept is good, but the driving feel is a bit weird at slow speed and that's when the clutches wear the most
great video, super informative
i loved the snap ring removal tool, yesterday i used that tool to remove siged car wiper bolts, i keep two of them handy 4 inch and 5 inch chorded and chordless
Your videos go so quick
👍👍👍thanks millions bro. you do better job than my teacher does!!
Damn......... this guy is VERY Good..!!!
Thank You My Friend 🙂
Excellent teardown, definitely a great transmission, too bad their TSI suck. FYI drain and fill is pretty easy, once drained you can fill through the filter. It's a little slow but works fine.
Good to know. That probably would make a mess though
@@speedkar99 Not at all use a long neck plastic funnel, melt the end to the filter port hole easy peasy.
Very helpful...thank you
Thanks for not wasting my time. Very interesting.Looks like some motorcycle technology there.
Those clutches are likely original. These DQ250 gearboxes are very robust. My passat tdi just hit 193k miles (300k something km) and scantool reports plenty of clutchlife left. Car has full service history, the transmission is all original, even the dual mass is!! Which was shocking to see for me, having had multiple dmf failures on manual vws before. I drive my car very spirited and this gearbox is amazing. Never ever had any problems with it. Sometimes it can jerk a bit in heavy traffic, but its very occasional and only when you are messing around with the pedals, you kinda have to drive it with purpose lol. I loved driving manual but eversince i got a dsg i dont think ill ever go back. With flappy pedals it feels almost like a sequential.
People are scared of these because "they fail a lot". The thing is, they only fail if you dont change the fluid. That will kill it for sure.
Agreed. I think it's well engineered except for maybe the Mechatronic unit that might fail. But that's better than replacing the whole CVT 👀
@@speedkar99 For sure :D
Pretty cool video man, I’d love for you to do a transmission review of Honda’s 10-speed transmission & the ZF 8HP series as well.
"It's not winter yet" 🤣 Subscribed!
@speedkar99 legit?
@@Sera5e hell no
@@StevMaHo Typical, I never win anything 🤣
this video is sponsored by oral B. your trusty teaching tool in engine parts
"It's not winter yet!" - PMSL! You have the driest sense of humour!
Lol it's true... today was 18*C
I always noticed on every transmission that reverse tends to be ratioed between First and Second gears.
DSG is an initialism for DirektSchaltGetreibe, which is German for... Direct-Shift Gearbox. ;)
Yes, direct shift gearbox
I would have to go to Yale University for 10 years to learn what I've learned from this 1 video.
"It's not winter yet." LoL
When it's winter I'm sure she'll be looking
Brilliant.
The guy I bought my car from said his family owned a VW with a DSG, and they sold it with close to 200k miles with the original DSG still working well. He said they maintained it with regular fluid and filter changes. MAINTENANCE IS KEY!
People don't do maintenance and then say that a car is unreliable, like not changing the timeing belt and then saying a chain is better (i personally prefer a belt that i know when to change rather than a chain with plastic tensioners that idk when to change and are just gonna fail)
Simply amazing what men have invented.
god i love these videos
dual clutch doing 300 000 km and still in good condition , great engineering in that
The speed and frequency of shifts is far higher/faster than any normally driven manual gearbox. The shifts are done in the background up or down depending on the mechatronic logic, only actually engaging when the clutch on that shaft is engaged and on the old ratio’s shaft clutch disengaged. So there’s never a load on the shaft and synchroniser that are idle even though the synchroniser may shift several times before finally the clutch is used to engage drive on that shaft. The mechatronics working the piston that shifts the selector and therefore the next ratio up or down has no damper and the ram works extremely quickly and forcefully. I’ve bench tested these things using compressed air rather than hydraulic fluid and the changes are what most mechanically sympathetic people would call ‘brutal’.
It just occurred to me you use everybody's old clothes to clean up the mess but yours.🙂🙂
Yep that's how it works around here 😉
@@speedkar99
Hahaha. Sneaky.
I have a 2021 Kia Sorento with the 8 speed wet DCT. Aside from the clutch setup and number of gears it's basically the same basic functions.
Yes, it's mechanically a manual transmission
Please make more videos on electronics
I own Acura TLX with 8 speed dct with torque converter. I do get confused moments on very low speed sometimes, but I love that transmission. Especially on the s sport mode when when it does rev matching downshift. It shifts faster then anything. Every time I drive my other cars, I realize how boring planetary based automatics are. And manual in no match either.
DCT sure shifts fast! I wonder how different Hondas DCT is than this VW
wow its complicated soooo many things can go wrong
It's way simpler than a torque converter automatic (but not as simple as a manual)
@@Giuliana-w1f VW TDI isn’t that automatic tourque transmissions?
@@EnergySeeker this one is a dual clutch automatic, a torque converter automatic is way worse (this one is almost a manual with hidraulics, electronics, and a weird clutch)
@@Giuliana-w1f double clutch that is , !!!yes very weird
Great !
Nice 😊
Thanks
Great video. I prefer VW’s approach to DCT’s over Honda/Nissan going to CVT’s, both in terms of performance durability. Which do you prefer having taken both apart?
DCT
It's basically a manual transmission and you can replace just the Mechatronic unit as opposed to the whole thing when it fails.
I thought honda and toyota CVTs go for over 200000 miles though.
The larger clutch pack is for 1st gear plus etc ?
Ohhh. I always thought the final drive gears was included with the clutched mass. I guess it makes sense that those would be unclutched though, lowering the inertia for synchronizing.
Final drive typically means the differential right at the wheels
@@speedkar99 Yeah. I just thought the twin clutch idea was a clutch on the input between engine and input shaft, and another clutch between the final drive and the output shafts. Don't know what system I was looking at that worked this way, but I just assumed they all worked that way.
If I don’t shift from drive to sport mode at all, would it prolonged the clutch disc life more than 100K or maybe 200K? I have a dct transmission in my 2017 ioniq
I’m looking at getting a 2019 VW golf sportwagen with the 1.8T FWD. any problems I should look out for?
Maintenance and rust
Great video, I am trying to find a problem my dq500 is having with going into drive. When I start the car and put it in drive it won't engage until the car is completely warmed up. If I give it a little gas it will engage but it slams in so hard the tires chirp. Once the car is warm it engages fine and drives and shifts with no issues. I replaced the hydro tubes hoping that would fix it but it didn't. Any idea what would be causing this? Thanks
Sounds like you aren't getting enough fluid pressure
@@speedkar99 What controls the fluid pressure? I am stumped on what to replace.
Notification Squad!🔥🔥🔥
He should have said his wife was running the leaf blower. Good revenge for stealing so many toothbrushes.
Haha 😅
@@speedkar99 Be honest it was revenge for her missing clothes. Any chance you can tear down a Mazda Skytec G with a 6 sp auto?
@@speedkar99 Be honest it was revenge for her missing clothes. Any chance you can tear down a Mazda Skytec G with a 6 sp auto?
I'd really like to see a teardown of a high end Audi transmission.
Like a DCT?
Dude.
Like, Dude.
I like the custom snap ring tool. Did you make it, yourself? If not, where can I buy one?
Canadian Tire
Canadian Tire
Where can I get one of those circlip removing tools?
I got mine at Canadian tire, like 10 years ago
hello what will happen to the Dual transmission when drive is disengaged and moved to Neutral in around 90MPH speed ?
I'm just nodding and smiling politely pretending I know what's going on. But I'm the same with traditional auto transmissions. It's all magic.
My question is how they change gears smoothly when they are friction clutches engaging so fast. On manual transmission, if you release the clutch quickly you will experience a slight jerk even if in correct rpm.
You should do the infamous power shift dct from the Ford Fiesta
I'd love to get a fiesta or focus DCT. I got a focus engine teardown coming soon though 🙂
Ford Powershift DCT's actually work pretty well and are reliable once the leaky input shaft seals are replaced with the updated ones and the oil soaked dry clutches are replaced. Ford created a nightmare for itself by manufacturing these transmissions and putting them in cars when they knew about the problems with the leaking shaft seals. I rode in one of these just today that was fixed at a Ford dealership three years ago and it works perfectly.
Please, I have a low speed whine when coasting from about 40mph down to about 20mph which i believe is coming from the transmission. What could it be? It's a 2006 Acura TSX auto. With 155k miles.
5:20 to 5:25 is exactly the sounds I make after taking Metformin 😢
I wish these and CVT’s were reliable. A DCT is incredible for sporty applications & a CVT is great for keeping small engines in the economy RPM range. Unfortunately… well you know the reality of the situation
Yea these need more work but R&D budgets are now refocused to electric vehicles so there's no point in transmission development
Then you have companies doing stupid stuff like adding pretend shifts to CVTs. It kinda defeats the purpose.
The problem with CVT's is that the belts wear under the heavy loads encountered when the vehicle launches from a dead stop. Toyota has come up with a solution to this problem called a launch gear. During the initial acceleration a conventional gear propels the vehicle instead of the CV belt. Once the vehicle reaches a certain speed the transmission disengages the launch gear and engages the constant velocity mechanism. This saves wear on the belt and drastically extends the life of the transmission.
Vw dsg gearboxes are reliable!,