Autoholics Blog

Autoholics

Your daily fix of automotive news and car-crazy culture. The blog written by gearheads, for gearheads.

Previous in Blog: What's the Fastest Police Car?   Next in Blog: Incentives for Observing the Speed Limit?
Close
Close
Close
19 comments
Rate Comments: Nested

Do You Trust Continuously Variable Transmissions (CVT)?

Posted December 10, 2010 8:30 AM by CarDomain

I've only driven a few vehicles with them and could never get used to the way they feel. I'd also be hesitant to own one from a reliability standpoint. But they seem to be increasingly popular - just check out this news from GM.

"General Motors is considering the introduction of continuously variable transmissions in its next round of small cars in an effort to improve fuel efficiency. This will not be GM's first application of CVTs. In the early 2000s, the automaker used CVTs in the Saturn Ion coupe and Vue crossover, as well as the Opel Astra hatchback overseas. This CVT was not well received, however, and was discontinued at the end of the 2005 model year."

What do you think?

Visit Autoholics

Reply

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#1

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/10/2010 9:12 AM

I've never driven a vehicle with a CVT.

I will say this though, everything felt very squirrelly when I switched to power steering and brakes from manual, I didn't like it at all. For that matter, the automatic transmission felt weird too, after switching from a manual.

Sometimes we just don't like change, whether it's better or not.

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Reply Score 1 for Good Answer
Guru
Engineering Fields - Electromechanical Engineering - Technical Services Manager Canada - Member - Army brat Popular Science - Cosmology - What is Time and what is Energy? Technical Fields - Architecture - Draftsperson Hobbies - RC Aircraft - New Member

Join Date: Sep 2006
Location: Clive, Alberta, Canada
Posts: 5916
Good Answers: 204
#15
In reply to #1

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/11/2010 6:23 PM

"switched to power steering and brakes from manual"

you have to learn to not use the brake pedal as a clutch for automatics to become smooth...

Reply
Guru
Popular Science - Cosmology - New Member Engineering Fields - Civil Engineering - New Member Engineering Fields - Nuclear Engineering - New Member United States - Member - New Member

Join Date: Aug 2010
Posts: 714
Good Answers: 38
#2

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/10/2010 12:17 PM

As Kramarat points out, it might just be resistance to change.

There are too many benefits to a CVT to not continue pursuing the idea. I'm all for CVT's, I have a design for one in fact! Even so, I hesitate to buy a vehicle with one because it hasn't been around long enough to find the "bugs." For most people a vehicle is a major purchase and I simply don't want to add in another factor in what is often a gamble to begin with.

__________________
Sometimes my thoughts are in a degree of order so high even I don't get it...
Reply
Anonymous Poster
#3

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/10/2010 1:25 PM

If you don't try it, how are going to know unless you have had bad experience with it and hesitate to go back. even if when you are driving the manual, aren't you always trying to smooth your gear shifting with the clutch?. Anyway, I have tested drive the recent Altima or Maxima. it is very smooth, no shock. Just a bit lazy at the beginning of the acceleration.

Reply
Guru
Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
Location: Harlow England
Posts: 16512
Good Answers: 670
#4

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/10/2010 5:34 PM

Presumably it won't change gear on you when you are accelerating round a bend like some automatics... grrr, just what you don't want on a greasy roundabout...

Oh that's why I'm greasy,
I'm greasy like Sunday morning.
Del

__________________
health warning: These posts may contain traces of nut.
Reply
Guru
Popular Science - Cosmology - New Member Engineering Fields - Civil Engineering - New Member Engineering Fields - Nuclear Engineering - New Member United States - Member - New Member

Join Date: Aug 2010
Posts: 714
Good Answers: 38
#5
In reply to #4

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/10/2010 5:48 PM

Yep, that's the idea. When accelerating the engine can stay at exactly the same speed, its just the transmission that changes "RPMs" and does so smoothly. In theory the difference one would notice is a smoother ride (no gear changes) and little to no change in the engine speed (noise).

__________________
Sometimes my thoughts are in a degree of order so high even I don't get it...
Reply
Guru
Engineering Fields - Optical Engineering - Member Engineering Fields - Engineering Physics - Member Engineering Fields - Systems Engineering - Member

Join Date: Apr 2010
Location: Trantor
Posts: 5363
Good Answers: 647
#10
In reply to #5

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/10/2010 10:57 PM

I test-drove a Nissan Rogue a couple years ago that had CVT. It also had paddle-shifters mounted by the steering wheel. During an acceleration the engine RPMs increased a lot. As It was explained to me, the CVT automatically adjusted the RPMs of the drive train for maximum efficiency (I think to ride the peak on the power-band curve). I tried the paddle shifters; ho-hum. They fed a signal to the computer that controlled the CVT, so 1st, 2nd, 3rd... gears were actually software preset values.

It was an interesting experience; but I bought a Rav4.

__________________
Whiskey, women -- and astrophysics. Because sometimes a problem can't be solved with just whiskey and women.
Reply
Guru
United Kingdom - Member - Not a New Member Hobbies - Musician - New Member Hobbies - Fishing - New Member

Join Date: May 2006
Location: Reading, Berkshire, UK. Going under cover.
Posts: 9684
Good Answers: 468
#12
In reply to #10

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/11/2010 5:42 AM

Drove a hired Honda Jazz (AKA Fit in the US) with CVT for a few hundred miles a couple of years ago. Sounds like a very similar arrangement. Interesting variation was a "sport" setting, which selected a different group of preset ratios. Was quite fun up & down the fell roads in Cumbria.

Still prefer manual fixed ratios -think there's maybe too much to go wrong in fly-by-wire[1], but perhaps I'm just getting old.

[1] It's not as if most private cars get the kind of service attention & treatment as an aircraft.

__________________
"Love justice, you who rule the world" - Dante Alighieri
Reply
Active Contributor

Join Date: Dec 2009
Location: Montreal - (St-Laurent)
Posts: 12
#6

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/10/2010 10:34 PM

CVTs are coming back after unsuccessful introduction by some automakers.

If properly managed (engine-CVT interaction), CVTs are able to better explore the engine performance map, and therefore can deliver better fuel efficiency and smooth operation. Not many automakers got it right...! But they start to getting better... The point is; during acceleration CVTs should not keep the engine RPM constant, they should change the opening of the throttle and the CVT ratio to stay on optimum efficiency curve of the engine, once the constant speed is achieved.

The conventional 6,7 or 8 gears ATs are not the answer...

Reply
Power-User

Join Date: Jan 2010
Location: Atchison Village
Posts: 383
Good Answers: 39
#7

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/10/2010 10:40 PM

I drive a 2000 CVT and love the hell out of it! Had one in 1954, too. Guess which vehicles they are! My favorite was the DAF, with two CVTs from one engine.

__________________
Align culture with nature...
Reply
Guru

Join Date: Feb 2008
Location: Large hole formally occupied by furry woodland creature.
Posts: 3385
Good Answers: 97
#13
In reply to #7

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/11/2010 10:19 AM

I had a Salisbury scooter with a CVT belt drive, similar to the DAF which had two (one for each drive wheel) They were different than the modern snowmobile drive in that instead of a spring loaded driven pulley, both drive and driven shivs where centrifugally actuated with flyweights.

The smoothness of the scooter drive system, through both acceleration and deceleration, was amazing.

__________________
CRTL-Z
Reply
Power-User

Join Date: Oct 2010
Location: Indian Mills,Southern N.J.
Posts: 140
Good Answers: 5
#8

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/10/2010 10:43 PM

snowmobiles and ATVs have been using the cvt for along time. I have it on my Suzuki 4x4 quad and have never had a problem, I have larger more aggressive tires on it and its been threw #$$%^&*. and has never failed. A guy at work bought a Nissan maranno when they came out with the cvt. 200-k and still going strong. it is a bit of a strange feeling accelorating , kind of feels like an elevator,but very easy to get use to. it feels like your always in the correct gear for the power band. i like it

__________________
anyone can F--*#@% up a design.It takes a good Man to fix it. Macgyverism at its best.
Reply Score 1 for Good Answer
Active Contributor

Join Date: Dec 2009
Location: Montreal - (St-Laurent)
Posts: 12
#9
In reply to #8

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/10/2010 10:54 PM

More and more people like them. Get ready for the spread of CVTs.

Murano was very successful introduction of CVTs. Subaru Justy ECVT was a catastrophe... Not that much the CVT, but terribly wrong interaction with the engine.

That was a huge "black eye to CVTs popularity..."

With power split CVTs (CVPST), and using electric motor supplying power to the countershaft of the transmission, we can achieve clean acceleration by using the electric motor power and ICE power to accelerate. We can stay on optimum efficiency curve, even during transient conditions (acceleration), when normally we get the spikes in emissions.

Reply
Guru

Join Date: Apr 2006
Location: Cincinnati, Ohio, USA
Posts: 662
Good Answers: 49
#11

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/11/2010 12:18 AM

I have been driving one in a Toyota Camry Hybrid and a Toyota Highlander Hybrid since early 2007 and I love it.

If you don't trust it- do you trust your belt-driven fans or pumps? Why the difference in trust levels- it's the same thing except that the pitch diameter changes.

What is great is that the "first" gear- startup- is SO LOW that you get phenomenal torque and dig off the line. The engine goes to maximum torque (4700 RPM) almost immediately and stays there, then the drive begins to "shift", increasing vehicle speed. My 4x4 Highlander will chirp tires on dry concrete from a dead stop if you punch the throttle. The traction control kicks in when the Camry is punched on dry pavement even with high-traction rated tires.

The only down side is that the towing capacity of the Highlander is only 3500 Lbs vs 5,000 with a standard automatic. BUT- between the electric drives and the full power engine/drive package the 4700 Lb 4x4 Highlander V-6 goes from 0-60 in 6 seconds and the 4100 Lb 2WD Camry Inline 4 takes 7.2 seconds from 0-60. Extra weight is the battery pack at the bottom of the vehicle- great ride and tight turns.

__________________
NO MATTER HOW WELL YOU HAVE DONE SO FAR, ALWAYS TRY TO BE BETTER TOMORROW.
Reply
Anonymous Poster
#14

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/11/2010 2:37 PM

I personally don't think I need one, I don't like that the trans adjusts all the time, adj means wear as the gearing in a regular transmission is almost wear free and the only time real wear takes place is during shift, now we have 6 and 7 speed automatics, must be expensive to rebuild them, but now cars aren't meant to be on road more than 7 years, electronics will obsolete cars in 10-12 years, give me a 4 speed auto with a lockup torque converter and I will work my own gears and rpms, took me a long time to decide I like auto trans, as I got older I got lazy and now I like the ease in traffic of the auto, however I can fix my own when it bellies up, so it won't cost me $2300.00 to have rebuilt replacement so my coment is biased. I would like the option of a paddle shift on my merc mystique 2 ltr 4 cyl, running the gears when I want is better then the computer doing it by code parameters.. every now and then it makes poor decision.

Mitch
retired peugeot mech

Reply
Active Contributor

Join Date: Dec 2009
Location: Montreal - (St-Laurent)
Posts: 12
#16
In reply to #14

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/11/2010 6:30 PM

Quote: "...every now and then it makes poor decision."

There is not much to wear in CVTs during a smooth adjustment of the ratios. If the algorithms are poorly constructed, CVTs will make poor decisions. But otherwise, with well written algorithms the CVT transmission will follow the best possible path, which even best driver is not able to emulate using MTs. So much has been proven with automated MTs. I understand there are CVTs with option to choose the predetermined ratios when driver wishes. That is an abomination [forced upon engineers by commercial departments], and is done to cater to many drivers (general public) who think they may have better acceleration in "sporty" driving if they are able chose the moment of the shift... Anything like that is far from the truth! Using properly designed CVTs, the acceleration of the car is better, as we can have optimum excess of torque [for acceleration, too much is no good...] than with manual discrete ratio transmission (MT). David Coulthard, when driving for Williams, tried CVT in one of the cars, and was one second per lap faster than any other Williams car... One second per lap in F1 is the eternity...! Who remembers the guy finishing ~60 sec. behind the winner...?

Just watch... with constantly improving [dry and wet] CVT belts, - the CVTs are next thing to be used in cars... before we have the [battery] technology to make the competitive BEVs

Reply
Guru

Join Date: May 2009
Location: Wolfe Island, ON
Posts: 1357
Good Answers: 109
#17

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/12/2010 4:38 PM

My wife has a new Suzuki Kazashi with CVT as standard option. It is a little sluggish at the low speed during take-off but is equipped with paddles and manual overdrive. These paddles make the engine much more responsive at low speed acceleration but after that the CVT runs by itself just fine. Very nice to drive. Not sure my wife needs the fast takeoffs and she doesn't use the paddles. In fact I do not use them either. Not sure we need the testosterone acceleration but it is there for show and tell when needed. I am not concerned about the CVT failing as I have 150,000km/8 year warranty on power train.

__________________
If they want holy water, tell them to boil the hell out of it.
Reply
Guru

Join Date: Feb 2008
Posts: 638
Good Answers: 45
#18

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/13/2010 3:29 PM

I do trust CVTs. I own a Honda Civic Hybrid with CVT.

It runs smooth (no jolt between gear changes).

I suspect it lacks some starting torque for initial accelerations. Other than that, I like it.

__________________
This moment is as it should be.
Reply
Anonymous Poster
#19

Re: Do You Trust Continuously Variable Transmissions (CVT)?

12/16/2010 9:08 AM

We own a 2006 Ford Five Hundred with the CVT transmission. I was extremely disappointed to find out that Ford was discontinuing the use of the CVT. We have over 70,000 miles and have not had a single problem. in fact, i actually dislike driving a vehicle without the CVT now. we love it.

Reply
Reply to Blog Entry 19 comments

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

Anonymous Poster (3); Automotive Engineer (3); ChaoticIntellect (2); chrisg288 (1); darren2264 (1); energygod (1); JohnDG (1); kevinm (1); kramarat (1); ormondotvos (1); szwasta (1); Unredundant (1); Usbport (1); user-deleted-1105 (1)

Previous in Blog: What's the Fastest Police Car?   Next in Blog: Incentives for Observing the Speed Limit?

Advertisement