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GOV5

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Discussion starter · #1 ·
Some of you have mentioned the type of transmissions you have n your Honda, toyota, and Nissan Cars. My wife's Nissan Rogue has a CVT. I don't understand the difference in the CVT tranny and the DCT that Honda Motorcycles have.

Can anyone here explain in simple, non-mechanic terms how the differences, if any, affect the driver? I.e., can the driver actually hear or feel the difference in a car or motorcycle?

Sorry if this sounds childish, but it's something that has bugged me because I don't understand it.
 
#2 ·
Different Items. DCT is a dual clutch transmission, CVT is continually variable transmission. Here's a good article on them both

Automatic Transmissions – AMT takes on AT, CVT, DCT

Auto Tech Review is India’s leading automotive-technology magazine, focussed on the growing automotive engineering industry and community. The monthly magazine takes a 360-degree approach to journalism, and disseminates information and knowledge through its print, online & digital platforms...
autotechreview.com autotechreview.com
 
Discussion starter · #3 ·
noviwinger said:
Different Items. DCT is a dual clutch transmission, CVT is continually variable transmission. Here's a good article on them both

Automatic Transmissions – AMT takes on AT, CVT, DCT

Auto Tech Review is India’s leading automotive-technology magazine, focussed on the growing automotive engineering industry and community. The monthly magazine takes a 360-degree approach to journalism, and disseminates information and knowledge through its print, online & digital platforms...
autotechreview.com autotechreview.com
Click to expand...
Thanks for the article. It explains the "technical" differences, which btw was over my head. LOL. But that was only half of what I asked. What I really wanted to know was what differences the rider/driver experienced between the two..if any difference at all.
 
#4 ·
The DCT is essentially a manual transmission with computer controlled shifting. A CVT is a very sophisticated torque converter without discrete gears. The DCT is more efficient but the CVT is better at keeping the engine in an optimum RPM range.

As you use the transmission, you will hear and feel the DCT change gears. With the CVT you will accelerate and decelerate without feeling specific gear changes.
 
#5 ·
GOV5 said:
Thanks for the article. It explains the "technical" differences, which btw was over my head. LOL. But that was only half of what I asked. What I really wanted to know was what differences the rider/driver experienced between the two..if any difference at all.
Click to expand...
GOV5, the DCT is really a manual transmission that shifts automatically - I think of it as having a tiny person that lives inside the transmission and does the shifting for us based on various factors (of course the tiny person is actually the computer and the clutches). So, riding the DCT is just like riding a manual transmission bike, except that you don't have to do the shifting. You can hear and feel it changing gears.

A CVT is also a direct connection and you can kinda-sorta think of it like a motorcycle with a chain drive that has a variable size countershaft sprocket and a variable size rear wheel sprocket (that change diameters as you ride). The CVT uses an internal chain typically between cones front and rear (no sprockets involved, through) that either squeeze together or retract as you drive in order to make the front or rear diameter sizes larger or smaller (based on what the computer decides). The effect is that the engine can stay at a fairly constant rpm as you accelerate.

I have driven an older Subaru (2014) with a CVT and did not like it at all - it just goes errrrrrrrrr when you give it the gas to accelerate. It works fine, but reminded me a little of a cow mooing. Certainly not the "shifting" behavior most goldwing owners would want. My understanding is the newer CVTs now somehow incorporate "fake" shifting to make them seem a little bit more like a regular automatic - not sure how those work, though.

Hope this helps a little.
 
#7 · (Edited)
The most basic answer is "there is no difference". Push the go pedal and they both go faster.

For a person that may be more in tune mechanically there is a lot of difference. A CVT continously changes the ratio between two pulleys inside the transmission. There is no feeling of engine rpms rising in a direct relationship to road speed like happens in a manual transmission or a conventional automatic transmission. Gun a basic CVT and the rpms rise quickly but speed picks up in a manner that eventually catches up to the rpms - kind of like rubber band. When the driver lets up on the gas there typically is little engine braking as the ratios between driving and driven pulleys don't immediately change. I'm not saying a CVT cannot accelerate quickly, it's just the rapid rise of engine rpms do not match the rise of mph. Some manufacturers have added electronic "shift points" to CVTs so the car or scooter (Burgman) has the feel and option of choosing and holding a gear similar to a conventional transmission.

A DCT is basically 95% the components of a manual transmission with 5% extra being the computer controlled gear shift mechanism that turns the shift selector drum that a toe lever or hand shift knob does with a conventional manual tranny. There exists the basic "direct connection" of gas pedal to rpms and upon giving it the gas a DCT transmission still delivers the stair-step feel of rpms rising and falling in direct relationship to road speed as the computer upshifts conventional gears under acceleration. Under deceleration the available engine braking from the selected gear is apparent. Conventional hydrostatic automatic transmissions of the last 70 years use a liquid like oil, ATF, or hydraulic fluid to make the connection between the engine and gears - a torque converter. This indirect fluid connection softens or eliminates the direct connection a driver feels between the engine and rear wheels and can deliver a seamless even sensation during acceleration - even with 7 or 8 speed automatics shifting under acceleration. It's not bad or good, it's just the way of a hydrostatic automatic. Honda/Acura developed a hybrid torque converter DCT transmission to deliver the seamless shifting of a hydrostatic transmission because a DCT can feel and sound "manual" as the computer stirs the gears and there are many people that have never driven a manual transmission and think the feel of shifting gears is not to the expectation of a modern automatic.
 
Discussion starter · #10 ·
pauln said:
GOV5, the DCT is really a manual transmission that shifts automatically - I think of it as having a tiny person that lives inside the transmission and does the shifting for us based on various factors (of course the tiny person is actually the computer and the clutches). So, riding the DCT is just like riding a manual transmission bike, except that you don't have to do the shifting. You can hear and feel it changing gears.

A CVT is also a direct connection and you can kinda-sorta think of it like a motorcycle with a chain drive that has a variable size countershaft sprocket and a variable size rear wheel sprocket (that change diameters as you ride). The CVT uses an internal chain typically between cones front and rear (no sprockets involved, through) that either squeeze together or retract as you drive in order to make the front or rear diameter sizes larger or smaller (based on what the computer decides). The effect is that the engine can stay at a fairly constant rpm as you accelerate.

I have driven an older Subaru (2014) with a CVT and did not like it at all - it just goes errrrrrrrrr when you give it the gas to accelerate. It works fine, but reminded me a little of a cow mooing. Certainly not the "shifting" behavior most goldwing owners would want. My understanding is the newer CVTs now somehow incorporate "fake" shifting to make them seem a little bit more like a regular automatic - not sure how those work, though.

Hope this helps a little.
Click to expand...
THX a million! That was PERFECT! You explained it in way that even I could understand.
 
Discussion starter · #11 ·
dduelin,

" Gun a basic CVT and the rpms rise quickly but speed picks up in a manner that eventually catches up to the rpms - kind of like rubber band. When the driver lets up on the gas there typically is little engine braking as the ratios between driving and driven pulleys don't immediately change. "

I have felt this effect on my wife's car when I accelerate quickly. It's kinda odd waiting for the "kick-in" as I like to call it. I have read that the same is true for a jet plane, i.e., you have to anticipate when you need the extra push, because it takes a second for the power to be delivered after the pilot adds more thrust.
 
#12 ·
There are different types of CVTs. Some are very basic, like those on off-road UTVs, which use small roller weights and centrifugal force to expand the size of the drive pulley. Some CVTs, like those used in cars and on the Suzuki Burgman 650, use a computer to control the expanding and contracting of the drive pulley. One advantage to computer controlled CVTs is they can simulate actual gear changes and lock the transmission in a desired gear position.
 
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#13 · (Edited)
GOV5 said:
THX a million! That was PERFECT! You explained it in way that even I could understand.
Click to expand...
GOV5, thank you for the compliment! All of the replies in this thread have been very helpful - adding to a better understanding of DCTs/CVTs for all of us. It has helped me better understand how they get CVTs to "shift". This was/is a very informative thread. Thanks for asking the original question :)
 
#14 ·
GOV5 said:
Thanks for the article. It explains the "technical" differences, which btw was over my head. LOL. But that was only half of what I asked. What I really wanted to know was what differences the rider/driver experienced between the two..if any difference at all.
Click to expand...
With the exception of the CVT, it all has to do with the attitude of the shift. Some will shift smoother, some faster, some softer, some more cushy. With the CVT, once it's applied there is no shift ... like a centrical clutch used on lawn owners, and mini bikes from the 60's ... remember those and how they worked ???
 
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#15 ·
I haven't ridden anything with a CVT, so can't really give an opinion on how smooth it operates compared to a DCT, but I did find the following article and two videos explaining how a DCT and CVT work. I needed to watch the DCT video several times to understand the mechanics, but it's rather ingenious in how it all comes together.

www.revzilla.com

Motorcycles and automatic transmissions - RevZilla

A look at motorcycles that do the shifting for you.
www.revzilla.com www.revzilla.com
 
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