"Automatic" transmissions
Thread Starter
Joined: Oct 2002
Posts: 34,131
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From: Canton, MA
"Automatic" transmissions
What I have learned about modern automatic and DSG trannies has come in dribs and drabs from skimming car magazine tests and I never took time to try to put it all together. I'm still not sure I have it all sorted out.
I have never driven a DSG car. For those unfamiliar with the technology, the transmission has two clutches and two concentric shafts that transmit power to two separate sets of gears. When going forward you are transmitting power through one of the clutches to one of the sets of gears. When you shift, you disengage the clutch plate that is driving the current gear and engage the clutch plate that drives the next gear. So the gears can be switched almost instantly and avoids the need to slide one gear out of the way before the next slides into place. Here is what VW says about it:
http://en.volkswagen.com/content/vw_...-getriebe.html
Wikipedia has a better detailed description with some little pictures that help understand the relation between the clutches and the gear sets.
http://en.wikipedia.org/wiki/Direct-shift_gearbox
Earlier examples had some problems with being clunky or jarring. I wonder how well they work now?
Meanwhile, it seems the traditional automatic transmission has made great strides in shifting performance and often results in a car that is faster than the manual version, at least in terms of acceleration. I'm sure you have all read about this. A recent example I have studied is illuminating. The latest offering from BMW in the M235i has eight forward speeds and shifts so quickly in knocks over a half second off the 0 to 60 and 1/4 mile time of the car when equipped with a manual. In fact, the automatic tranny M235i matches the acceleration of the 2012 M3 coupe.
http://www.caranddriver.com/reviews/...ic-test-review
I'd like to hear from those who have sampled some of this technology and hear your opinions.
I have never driven a DSG car. For those unfamiliar with the technology, the transmission has two clutches and two concentric shafts that transmit power to two separate sets of gears. When going forward you are transmitting power through one of the clutches to one of the sets of gears. When you shift, you disengage the clutch plate that is driving the current gear and engage the clutch plate that drives the next gear. So the gears can be switched almost instantly and avoids the need to slide one gear out of the way before the next slides into place. Here is what VW says about it:
http://en.volkswagen.com/content/vw_...-getriebe.html
Wikipedia has a better detailed description with some little pictures that help understand the relation between the clutches and the gear sets.
http://en.wikipedia.org/wiki/Direct-shift_gearbox
Earlier examples had some problems with being clunky or jarring. I wonder how well they work now?
Meanwhile, it seems the traditional automatic transmission has made great strides in shifting performance and often results in a car that is faster than the manual version, at least in terms of acceleration. I'm sure you have all read about this. A recent example I have studied is illuminating. The latest offering from BMW in the M235i has eight forward speeds and shifts so quickly in knocks over a half second off the 0 to 60 and 1/4 mile time of the car when equipped with a manual. In fact, the automatic tranny M235i matches the acceleration of the 2012 M3 coupe.
http://www.caranddriver.com/reviews/...ic-test-review
I'd like to hear from those who have sampled some of this technology and hear your opinions.
Former Moderator
Joined: Oct 2003
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From: Houston/Durango
Bill, as you know some of the BMWs have the dual clutch automatics. The 2013 1 just bought has the DCT with paddles. So the 2014+ M235i AT trannies have 18 gears instead 0f 17. Not only are the 0-60 times for these ATs faster than with a manual; the fuel mileage is also better than the stick. Many drivers now also prefer them at the track; no more need to heel and toe. I think I would still maybe prefer the manual tranny over the automatic, but I think this DCT automatic is super. I use the paddles quite a bit in driving it. but haven't had it on the track yet.
I think the only automatic transmission that Honda offers right now is their version of the CVT . Those I don't like at all -- anybody's version. I find that they tend to stutter, del, and and surge in stop and go traffic. Unfortunately the only Honda you can get at any normal Honda dealership has the CVT. and no manual is easily available except maybe in the Civic Si.
I think the only automatic transmission that Honda offers right now is their version of the CVT . Those I don't like at all -- anybody's version. I find that they tend to stutter, del, and and surge in stop and go traffic. Unfortunately the only Honda you can get at any normal Honda dealership has the CVT. and no manual is easily available except maybe in the Civic Si.
Joined: Oct 2001
Posts: 3,216
Likes: 34
From: NM/CO
I think the manual mode in my car works very well. Got a chance to drive it hard on some twisty roads and I got the gears I want when I asked for them, except if I tried to downshift with the rpm's above 4000, then it would not downshift. I would guess the logic is that it could over rev or hit redline too quickly, but I learned it early and I adjusted. Reviews I read, said the transmission paddles acted as a suggestion, but I never had that problem, the shift where quick and smooth, just a little harder at slower speeds.
I think that today autos have come a long way from those in the past and when you are talking about the ones in sports cars, sometimes it's hard to not see the advantage. There will always be those that will want the manual and I hope some manuals stay around, but they are getting far and few between.
I think that today autos have come a long way from those in the past and when you are talking about the ones in sports cars, sometimes it's hard to not see the advantage. There will always be those that will want the manual and I hope some manuals stay around, but they are getting far and few between.
Joined: Oct 2000
Posts: 9,579
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From: West Deptford NJ
Bill, as you know some of the BMWs have the dual clutch automatics. The 2013 1 just bought has the DCT with paddles. The 2014+ M235i model DCT trannies have 18 gears instead 0f 17. Not only are the 0-60 times faster than with a manual; the fuel mileage is also better than the stick. Many drivers now also prefer them at the track; no more need to heel and toe. I think I would still maybe prefer the manual tranny over the automatic, but I think this DCT automatic is super. I use the paddles quite a bit in driving it. but it is not nec.
I think the only automatic transmission that Honda offers right now is their version of the CVT. Those I don't like at all -- anybody's version. I find that they tend to stutter and surge in stop and go traffic. Unfortunately the only Honda you can get at any normal Honda dealership has the CVT. and no manual is easily available except maybe in the Civic Si.
I think the only automatic transmission that Honda offers right now is their version of the CVT. Those I don't like at all -- anybody's version. I find that they tend to stutter and surge in stop and go traffic. Unfortunately the only Honda you can get at any normal Honda dealership has the CVT. and no manual is easily available except maybe in the Civic Si.
Thread Starter
Joined: Oct 2002
Posts: 34,131
Likes: 126
From: Canton, MA
I think the manual mode in my car works very well. Got a chance to drive it hard on some twisty roads and I got the gears I want when I asked for them, except if I tried to downshift with the rpm's above 4000, then it would not downshift. I would guess the logic is that it could over rev or hit redline too quickly, but I learned it early and I adjusted. Reviews I read, said the transmission paddles acted as a suggestion, but I never had that problem, the shift where quick and smooth, just a little harder at slower speeds.
I think that today autos have come a long way from those in the past and when you are talking about the ones in sports cars, sometimes it's hard to not see the advantage. There will always be those that will want the manual and I hope some manuals stay around, but they are getting far and few between.
I think that today autos have come a long way from those in the past and when you are talking about the ones in sports cars, sometimes it's hard to not see the advantage. There will always be those that will want the manual and I hope some manuals stay around, but they are getting far and few between.
What car was this?
Thread Starter
Joined: Oct 2002
Posts: 34,131
Likes: 126
From: Canton, MA
Bill, as you know some of the BMWs have the dual clutch automatics. The 2013 1 just bought has the DCT with paddles. The 2014+ M235i model DCT trannies have 18 gears instead 0f 17. Not only are the 0-60 times faster than with a manual; the fuel mileage is also better than the stick. Many drivers now also prefer them at the track; no more need to heel and toe. I think I would still maybe prefer the manual tranny over the automatic, but I think this DCT automatic is super. I use the paddles quite a bit in driving it. but it is not nec.
I think the only automatic transmission that Honda offers right now is their version of the CVT. Those I don't like at all -- anybody's version. I find that they tend to stutter and surge in stop and go traffic. Unfortunately the only Honda you can get at any normal Honda dealership has the CVT. and no manual is easily available except maybe in the Civic Si.
I think the only automatic transmission that Honda offers right now is their version of the CVT. Those I don't like at all -- anybody's version. I find that they tend to stutter and surge in stop and go traffic. Unfortunately the only Honda you can get at any normal Honda dealership has the CVT. and no manual is easily available except maybe in the Civic Si.
Jim, everything I read says the M235 has an 8 speed ZF automatic, not the DCT.
http://www.bmwusa.com/Standard/Conte...and_Specs.aspx
Former Moderator
Joined: Oct 2003
Posts: 17,122
Likes: 629
From: Houston/Durango
That's a surprise. They started delivering the I35i back in 2011 already with the N55 engine and the 7 speed DCT tranny. Your M235i specs link doesn't seem to specify which automatic transmission it has.
My 2013 car has the DCT 7 speed.
Here's the 2011 link:
http://www.automobil.../#__federated=1
My 2013 car has the DCT 7 speed.
Here's the 2011 link:
http://www.automobil.../#__federated=1
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Thread Starter
Joined: Oct 2002
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From: Canton, MA
Joined: Oct 2001
Posts: 3,216
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From: NM/CO
Originally Posted by coop' timestamp='1426777968' post='23546422
I think the manual mode in my car works very well. Got a chance to drive it hard on some twisty roads and I got the gears I want when I asked for them, except if I tried to downshift with the rpm's above 4000, then it would not downshift. I would guess the logic is that it could over rev or hit redline too quickly, but I learned it early and I adjusted. Reviews I read, said the transmission paddles acted as a suggestion, but I never had that problem, the shift where quick and smooth, just a little harder at slower speeds.
I think that today autos have come a long way from those in the past and when you are talking about the ones in sports cars, sometimes it's hard to not see the advantage. There will always be those that will want the manual and I hope some manuals stay around, but they are getting far and few between.
I think that today autos have come a long way from those in the past and when you are talking about the ones in sports cars, sometimes it's hard to not see the advantage. There will always be those that will want the manual and I hope some manuals stay around, but they are getting far and few between.
What car was this?
Joined: Jul 2002
Posts: 1,884
Likes: 81
From: Toronto
I drove a EVO X for four years with a dual clutch transmission both on the road and the track. It was amazing as you could put in D, shift with the paddles or like a Sequential transmission pushing and pulling the shift leaver. Depending on the transmission setting it drove like an economy car or a crazed Racecar on the track burning a lot of gas !! One reading I remember was 56.4 liters per 100 Kms, so a full tank of gas in around 62 miles !!!
Most of the time I got lazy and put it in Drive which was one of the reasons I traded it for the BRZ. Was it worth the money ?? Yes
Most of the time I got lazy and put it in Drive which was one of the reasons I traded it for the BRZ. Was it worth the money ?? Yes