WTF are double clutches about/for?

[Arizona Wayne]

Many new cars have double clutches now and so do some Honda MCs.  I've heard some Ford cars have issues with theres.  Why do they even exist?   

I rented a Ford Fiesta that had a double clutch and it felt kinda funny when shifting.

[MGPilot]

A dual clutch lets the car be in one gear while the system anticipates your next gear, shift and get ready. Then all one clutch does is open while the other closes. Makes the mechanical shifting go a lot faster and there's no power loss due to a torque converter.

[Arizona Wayne]

A dual clutch lets the car be in one gear while the system anticipates your next gear, shift and get ready. Then all one clutch does is open while the other closes. Makes the mechanical shifting go a lot faster and there's no power loss due to a torque converter.

Well when I shifted on the Fiesta some times it seemed to take longer for the shift to complete.  I think that car has a 6 or 7 spd. tranny.  I thought maybe there are 2 clutches to engage all the gears.

[Arizona Wayne]

Also, on a car with a CVT tranny, does that mean it has a bunch of drive belts & pulleys?

[pyoungbl]

On the dual clutch autos that I am familiar with you just put the car into "D" and let the transmission do its thing.  Every shift is crisp but not a jerk.  I did notice that when I put on the brake the clutch disengages so at a stop I cannot just rev up the engine and expect to jerk away from the stop.  I have to first take my foot off the brake and then stomp on the accelerator.  All in all the dual clutch seems to be a pretty smart idea that is governed by how smart the ECU is.  Of course you can always override the ECu and shift as you please.

Peter Y.

[canuck750]

On the dual clutch autos that I am familiar with you just put the car into "D" and let the transmission do its thing.  Every shift is crisp but not a jerk.  I did notice that when I put on the brake the clutch disengages so at a stop I cannot just rev up the engine and expect to jerk away from the stop.  I have to first take my foot off the brake and then stomp on the accelerator.  All in all the dual clutch seems to be a pretty smart idea that is governed by how smart the ECU is.  Of course you can always override the ECu and shift as you please.

Peter Y.

My beemer has an 8 speed auto, shifts very smoothly, almost undiscernible, in my opinion it just makes the car more boring, I used to like the feel of a transmission snapping into the next gear, I guess they call this progress?

[Arizona Wayne]

I'm curious as how it all works and concerning maintenance of it compared to the old design.

[pyoungbl]

My best guess is that the dual clutch tranny is more fuel efficient than a traditional automatic transmission.  The AT had a torque converter that allowed the engine to run at idle but not drive the car.  When you increased the revs the torque converter would send power to the transmission but there was always a power loss.  Remember how we used to expect to get 2-3 mpg less with automatic transmissions?  With the DC system there is no torque converter.  The ECU is slipping the clutch just like you and I used to do.  Then the clutch engages and away you go.

As for cost, I suspect that will be significant when you have to replace the clutches.  Will it be more than rebuilding an auto trans...I don't have any idea.

On my Fiat 500L the dual clutch system works just fine.  I use it as an automatic transmission.  Were I in an area where there was an advantage to shifting manually I'm convinced I could have lots of fun rowing through the gears.  That's not the case here in the flat part of Virginia.

[Arizona Wayne]

Well I read up on the internet and now have an idea of what they are all about.   Since my scooters are CVT I had visions of a bunch of pulleys and belts doing all the speed changes.    But now know it's the same concept but a lot more durable and compact.    On the dual clutches 1 is for the odd# gears and the other clutch is for the even # gears.

[kirkemon]

My beemer has an 8 speed auto, shifts very smoothly, almost undiscernible, in my opinion it just makes the car more boring, I used to like the feel of a transmission snapping into the next gear, I guess they call this progress?

Your new BMW shifts faster than your older one - maybe more boring to you, but my Porsche has a PDK (Doppelkupplung) and I love it - when I use the Launch Control it's anything but boring (0-60 4.6sec not as fast as my motorcycles, but not bad for a cage).

[LowRyter]

I am stick shift guy.  I do the double clutching

 

[oldbike54]

I am stick shift guy.  I do the double clutching

 

 Yeah , we used to say real hot rods had clutches , guess now we have to say they only have one clutch 

 Dusty

[sign216]

I am stick shift guy.  I do the double clutching

 

 

[Arizona Wayne]

No synchros?   Back in 1960 I had a chance to be a school bus driver @ our High School.  All I had to prove was I knew how to shift the manual tranny that had no synchros w/o grinding gears.    I couldn't make the grade. Now I bet all the school bus trannys are automatics.

[canuck750]

Your new BMW shifts faster than your older one - maybe more boring to you, but my Porsche has a PDK (Doppelkupplung) and I love it - when I use the Launch Control it's anything but boring (0-60 4.6sec not as fast as my motorcycles, but not bad for a cage).

 0~60 in 4.3 seconds, no launch control, 4431 lbs curb weight, 4 doors, seating for five, big ass trunk but not built to offer the visceral feel of a Porsche. One day I would love to have a Carrera!

[fossil]

A double clutch is indeed more efficient than a conventional automatic transmission. And as it is tightly connected to the digital motor control it is also more efficient than a manual shifter.

Of course the fun of a stick is not there.

[Zoom Zoom]

Also, on a car with a CVT tranny, does that mean it has a bunch of drive belts & pulleys?

Think of it like old mini bikes, a belt and two pulleys that can change diameters. As one pulley gets bigger, the other gets smaller changing the ratio. I don't know about the others, but Subaru uses some type of chain for the belt.

https://www.youtube.com/watch?v=a3PF4fPXe9U

John Henry

[jetmechmarty]

My wife has a Ford Focus.  I really don't know what it has, but to me, it's six speeds of awful.  I avoid driving it. 

[charlie b]

Yep, 'automatics' are here to stay.  I like them.  If the VFR1200 wasn't so ugly I'd buy one.

[charlie b]

Sorry, but I am in the automatic camp.  Ever since I had the Mini Cooper.  It is humbling when an automatic shifts better than you do.  In sport mode it kept the engine in the proper rev range all the time, including downshifts.  I could not even beat it using the paddle shifters.  Maybe, if I practiced a lot, I could have beat it off the line, just because the turbo had a little lag to it.

I'd take a DCT with good programming any day.

Yep, you can 'be a man' and keep the clutch pedal/lever.  I'll take the auto.

[Hymes Inc.]

I understand that automatics shift faster then I can, just head to the drag strip, the fastest cars usually have autos. To me, while autos are convenient for people who are to stubborn to learn a manual (my wife), they take all the fun of driving away. I have more fun manually shifting a slow car then just sitting in a fast car that shifts for me. Anyone can drive an auto, I don't want to be anyone. Guess that is why I ride and old, hard to find, highly customized Moto Guzzi.

[drlapo]

I say ban all auto transmissions
Then let's see them drink coffee, text, talk and drive

[charlie b]

Well, I can still ride, drink coffee, text, and talk while on the Guzzi  :D

[drlapo]

Well I'm impressed

[oldbike54]

 Putting on my waders ...

 Dusty

[zedXmick]

I traded in my 2010 Kawasaki C14 on a new leftover 2010  Honda VFR 1200 DCT in March of 2012. The DCT is a sublime ride. It has two auto modes, D (drive) and S (sport)  D is for commuting,cruising around.... S is for back road fun time. :)  It also has manual shift levers (+ for upshifts)  (- for downshifts) on the left hand control. When you use the manual shift...you can make every shift at redline if you want... :)

I ride mine in sport mode about 80 percent of the time. On two lane back roads the sport mode really shines....the bike learns your throttle inputs and will adjust the shift points.. ie the more you get on it, the higher the shift points will be. The bike upshifts are seamless....even leaned over....on high speed sweepers.   The shaft drive feels like a chain driven bike...no pogoing of the rear end with throttle inputs.   I even had my first time track day in 2013 at Road America. I left it in sport mode the whole day.....the DCT was flawless the whole day....I never had to worry about blowing a shift....the best was coming off the looong front and back straights.....I could just hammer on the brakes and the bike would downshift seamlessly in the correct gear for the corner entry speed.... I see why this was banned in the GP class.  The linked antilock brakes are the best brakes I have ever used.... Never had any brake fade at Road America. Oh yeah I rode my bike to the track day...prepped it,did the track day and rode it back home. Here is the sport tourer in the wild.



At Road America







I think the DCT is here to stay in motorcycles. My VFR is the first generation of DCT,the new 2016 Honda African Twin is the third Gen of DCT. I cant wait to take a AT for a test ride. In Manual shift mode you still get the same feel shifting up or down through the gears....there is the same feeling of pulling that upshift lever as the tach climbs as when I used to pull that clutch lever on a manual motorcycle.

[pete roper]

I rode one of those Hondas when they first came out. Couldn't fault the transmission, or the motor apart from it being a bit characterless. What I did find though that it was almost impossible to ride slow! I took it out onto the Federal Highway and in seconds found myself exceeding 200kph! Not having to change gears made it even harder to keep speeds sane! For that reason alone I prefer my Mana!

With cars I really dislike Autos but having said that my mate Peter sagely pointed out that modern high speed diesels and DCT are a match made in heaven.

Pete

[Arizona Wayne]

Your VFR is shaft drive?  You've sold me on DCT trannies.

[bad Chad]

I figured you had a soft spot for trannies, Wayne, nothing wrong with that.

[Steve Scott]

My wife has a Ford Focus.  I really don't know what it has, but to me, it's six speeds of awful.  I avoid driving it.

 I had a Focus 5-speed that was truly a wonderful driver's car. Really great handling and on the backroads, it hit WAY above its weight class... I wonder what the difference could be?

A CVT can suck the fun out of anything. They're only acceptable to people who don't wanna drive anyway.

Conventional automatic transmissions aren't a whole lot better. In addition, every automatic I've ever owned has failed completely during my ownership. My experience is that every day with an automatic is one day closer to the day I have to walk home. It might be worth the hassle to have a torque converter on a big towing vehicle like my Expy (with rebuilt trans), or on a mindless family cruiser like our Voyager (with rebuilt trans), but on a real car I just don't get it.

DCTs are at least standard gearboxes at their root, so they lack the awful elastic connection between engine and axle, but their acceptability to someone like me is completely dependent upon the software, or at least on how unobtrusive its 'manual' mode is. Odds are good that the transmission is still going to do what it thinks is best even if that's not what I want.