Continuous Variable Transmissions

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Browser
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Re: Continuous Variable Transmissions

Post by Browser »

henry wrote:I have owned a 2003 Murano since new. After almost 10 years and 86,000 miles, no transmission issues.
How do you like the Murano? I've been shopping them and they seem nice. I'm somewhat concerned about the mileage they get, however.
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Re: Continuous Variable Transmissions

Post by henry »

Overall, I like my Murano. I have a 2003 all wheel drive model. No major mechanical problems. I get about 16-18 mpg when driving in town and about 23-24 mpg on highway trips.

I think most people wouldn’t even notice much of a difference between the CVT and a traditional automatic. Compared to other cars with automatics that I have driven, I do note there is more “engine braking” when you let off the accelerator, meaning the car slows more quickly when you take your foot off the gas. It also seems to hold a constant speed better when going down hills. One slight annoyance is that when going down very long steep grades, the car can get loud as the CVT rapidly adjusts to a lower gear and the engine revs increase.

About a year after I bought it, I had two episodes where after a long highway trip, I had trouble accelerating smoothly from a stop. I would step on the accelerator, the engine would rev and for at least a full second nothing happened and then the car would lurch forward and accelerate. Each time I had to pull over because the behavior was so disconcerting. I turned the car off and restarted it and everything was back to normal. I hasn’t happened again in many years but I still don’t know what caused it.

The alternator was replaced under a recall a few years ago but I’ve never had any problems. Thus far, it’s never failed to start and never left me stranded.
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Re: Continuous Variable Transmissions

Post by Clark & Addison »

NHRATA01 wrote:CVT's are great for efficiency. The challenge is making a pully and belt mechanism that can handle the torque of larger engines - I suspect this is why Nissan is having issues with the CVT behind their V6's like the Murano and Maxima. Off the top of my head I don't believe any other manufacturers put a CVT behind their V6. I believe the new Accord only offers the CVT with the 4 cylinder. I personally would probably avoid them on more powerful cars.
I don't know if Ford still uses a CVT on any of their V6 models, but our 05 Mercury Montego with all wheel drive has a V6 and a CVT. The transmission is very smooth, but the acceleration is not that great for a V6. It does what we need it to do, but we wouldn't beat too many others off the line if we wanted to.
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Re: Continuous Variable Transmissions

Post by ryuns »

Epsilon Delta wrote:
ryuns wrote:The Highlander hybrid paired a V6 with a CVT and hybrid drive. My mom drives a 2008-ish model and I noticed that consumer reports had the Highlander hybrid pegged at one of the most reliable used vehicles available. I imagine some Lexus hybrid have a similar setup? I imagine that the torque from the electric motor probably takes a lot of the pressure off of the tranny?
You may not understand how Toyota's synergy drive works. There is no separate CVT. The electric motors and controllers are the CVT. In particular there are no belts or cones and all of the gears are permanently meshed. Changing the ratio between the crank shaft and the drive wheels is done by manipulating electric currents in the motors rather than moving mechanical components.
Yes, thanks for the corrections. You're right. I should probably look up these things before posting, but in any case, it's here: http://en.wikipedia.org/wiki/Hybrid_Syn ... ansmission In practice, it seems to fulfill very much the same function as a CVT, but it's comparison in terms of reliability is probably not particular salient in this thread.
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Re: Continuous Variable Transmissions

Post by Browser »

Just test-drove a 2014 Suburu Forester 2.5 Touring with CVT. Overall, a pretty decent vehicle with good mileage ratings. Only knock was that the backup camera is a dinky 3-inch thing pretty far away under a cowling on upper dashboard. Virtually unusable for me. For some reason they don't share the larger GPS screen with the backup camera as other vehicles I've driven do, which would be 1000% better. Minor knock is that the back seats don't fold down completely flat, but not too bad. The only small SUVs I've found that do fold flat are the 2013 Rav4 and the Honda CRV. The 4-banger was a bit noisy under hard acceleration, but no more so than others I've tried lately. Actually the Murano V-6 with CVT howled even louder but the sound was powerful. The Sub is on my short list for now, but a decent backup camera screen would sure be nice.
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Re: Continuous Variable Transmissions

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henry wrote:Overall, I like my Murano. I have a 2003 all wheel drive model. No major mechanical problems. I get about 16-18 mpg when driving in town and about 23-24 mpg on highway trips.

I think most people wouldn’t even notice much of a difference between the CVT and a traditional automatic. Compared to other cars with automatics that I have driven, I do note there is more “engine braking” when you let off the accelerator, meaning the car slows more quickly when you take your foot off the gas. It also seems to hold a constant speed better when going down hills. One slight annoyance is that when going down very long steep grades, the car can get loud as the CVT rapidly adjusts to a lower gear and the engine revs increase.

About a year after I bought it, I had two episodes where after a long highway trip, I had trouble accelerating smoothly from a stop. I would step on the accelerator, the engine would rev and for at least a full second nothing happened and then the car would lurch forward and accelerate. Each time I had to pull over because the behavior was so disconcerting. I turned the car off and restarted it and everything was back to normal. I hasn’t happened again in many years but I still don’t know what caused it.

The alternator was replaced under a recall a few years ago but I’ve never had any problems. Thus far, it’s never failed to start and never left me stranded.
We also had a 2003 Murano SL AWD, but a rough trip on a rough "paved" road killed it in 2011. So, we replaced it with a used 2007 Murano SL AWD. I vaguely recall the acceleration problem for the 2003 model, but I believe it was a manifestation of an early production design. We didn't have the problem, but it was all over the internet at the time.

Fast-forward to 2007. It's much more refined and there are absolutely no issues with the CVT. In fact, you'll notice a distinct drop in performance when you drive a car that doesn't have a CVT (why is it shifting...). I only bought my Honda CR-V because I wanted a smaller SUV and tighter feel on the road. We purchased the extended warranty on the Murano because we got it used (with negotiation). I suspect we won't need to use it.
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Re: Continuous Variable Transmissions

Post by deanbrew »

Browser wrote:Just test-drove a 2014 Suburu Forester 2.5 Touring with CVT. Overall, a pretty decent vehicle with good mileage ratings. Only knock was that the backup camera is a dinky 3-inch thing pretty far away under a cowling on upper dashboard. Virtually unusable for me. For some reason they don't share the larger GPS screen with the backup camera as other vehicles I've driven do, which would be 1000% better. .... The Sub is on my short list for now, but a decent backup camera screen would sure be nice.
Interesting comments about the backup camera. I have very little experience with them, limited to the one in my wife's Honda van. It's in the rearview mirror, so it's quite a bit smaller than 3" - probably less than 2". I find it to be some help to make sure nothing is right behind the van, but it really doesn't help much with gauging how far I have between the van and whatever is behind it. It's marginally useful, but I wouldn't pay much extra for it. I guess I'll sound like an old fuddy-duddy, but I've driven for decades without a backup camera, so I'm not sure what all the fuss is about. I suppose it's one of those features that becomes important and desirable once you have it, like bluetooth or power mirrors or a rear window defogger.
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Re: Continuous Variable Transmissions

Post by Browser »

Many new vehicles are coming standard with the backup camera these days. I think all the 2014 Suburu Forester models have it so you don't have a choice. When the screen is pretty large it seems to be quite useful. The best I've seen is in the Acura RDX with 8-inch screen and a nearly 180-degree view. If they are too dinky, as in the Suburu, they are practically useless. And if the screen contrast is subpar, as in the 2013 Rav4, they are also useless. One thing I found quite nice in the 2013 Ford Escape is a backup warning alert if you are about to back into something. Might not save a kid back of you, but helps avoid backing into a parked vehicle or wall or something. Haven't found this on any other compact SUVs that I've looked at so far.
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Re: Continuous Variable Transmissions

Post by deanbrew »

Not only are they becoming more common, they are becoming ubiquitous. I'm fairly certain the feds have mandated that all cars have them soon.
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Re: Continuous Variable Transmissions

Post by communipaw »

. I'm fairly certain the feds have mandated that all cars have them [parking cameras] soon.
1. I believe you are right
2. I test drove a Camry V6 which had a parking camera. I was impressed that in parallel parking I could get to less than an inch of the car behind me without touching it and then could pull forward comfortably.
Very handy in the city.
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Re: Continuous Variable Transmissions

Post by fsrph »

Peter Foley wrote:We have a 2000 Subaru Forester with a 4 cy and a manual tranmission. It has plenty of power, enough even to pull a 1000 lb boat and trailer.
I have a 2010 Forester with the 4 cylinder engine. I have the manual trans too. Plenty of power with a very comfortable ride.

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Re: Continuous Variable Transmissions

Post by Browser »

Did a second test-drive of the 2014 Suburu Forester with CVT today. Seemed about the same as the first drive, except I noticed a little herky-jerky when taking off from a stop -- same thing as the Murano with CVT. Not too bad. You have a little bit of feeling that the accelerator is disconnected from the engine/transmission when you start up. Murano was the same but more noticeable. It has to be the CVT I'm thinking. Rapped with the Subaru sales manager and he seemed to be knowledgeable, though you never know how much hype they are feeding you. He claims that Subaru tested the CVT a long time before introducing it. In simulations, he said they put a million miles on the CVT tranny, inspected it, and then dropped that unit into a test vehicle that they drove across the country 11 times. I asked about the mechanics and he told me the "belts" in the CVT are wide kevlar-fabricated things. I couldn't help visualizing that metal gears instead of belts seems like a more reliable methodology. He confirmed that when a CVT tranny has a problem, the solution is to rip it out and completely replace it with a new unit. If you're under warranty no problemo -- but sounds like a more expensive fix than patching a geared tranny would be after your 36/60 is up.
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Re: Continuous Variable Transmissions

Post by LadyGeek »

I believe that can be classified as recency bias. You're asking about CVT, reading about CVT, so you're ignoring explanations that suggest other causes. Ignore the sales pitch and mechanic's opinions. You'll get the same treatment at any dealer, just swap the car names around.

What's your gut feel? Then go with it.
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Re: Continuous Variable Transmissions

Post by Browser »

Unfortunately my gut thinks that steel gears are more dependable than kevlar belts.
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Re: Continuous Variable Transmissions

Post by Epsilon Delta »

communipaw wrote: 2. I test drove a Camry V6 which had a parking camera. I was impressed that in parallel parking I could get to less than an inch of the car behind me without touching it and then could pull forward comfortably.
Very handy in the city.
When I were a lad they made you do that, blindfolded, as part of the driving test.

Kids these days, soft, soft I tell you. But I do wish the feds would mandate windows, they seem to be optional in some of the newer models.
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Re: Continuous Variable Transmissions

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Browser wrote:Unfortunately my gut thinks that steel gears are more dependable than kevlar belts.
This sounds like buyer's remorse. Treat the transmission and gear train as a black box which is perfectly reliable (nothing breaks) during the time you own the vehicle. Which one do you prefer to drive?
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Re: Continuous Variable Transmissions

Post by Jack »

The belt is constructed entirely of steel. You can see a video here:

http://www.youtube.com/watch?v=VmSmv6aiWqg

The steel belt works in compression, not tension. It works by steel pushing on steel, not pulling -- much like gears.
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Re: Continuous Variable Transmissions

Post by Browser »

LadyGeek wrote:
Browser wrote:Unfortunately my gut thinks that steel gears are more dependable than kevlar belts.
This sounds like buyer's remorse. Treat the transmission and gear train as a black box which is perfectly reliable (nothing breaks) during the time you own the vehicle. Which one do you prefer to drive?
I prefer the one that doesn't break. When they start putting CVT into Lexus, Infiniti, Acura, BMW, and Audi brand cars and the like then I'll start believing this is as reliable and performs as well as gears. Wonder why they don't?
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Re: Continuous Variable Transmissions

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Browser wrote:I prefer the one that doesn't break. When they start putting CVT into Lexus, Infiniti, Acura, BMW, and Audi brand cars and the like then I'll start believing this is as reliable and performs as well as gears. Wonder why they don't?
Well, 2 out of 5 is a start: Infiniti started using them recently, and Audi has been using them in the A4 for a while now, albeit with a few well documented complaints.

I agree with NHRA, although conventional CVTs have gotten better, most designs have steel-on-steel power transfer friction surfaces utilizing steel belts and cones/pulleys that are not necessarily robust for heavy torque applications, and not inexpensive to replace (not sacrificial like a clutch). For moderate power applications, with judicious use of limit clutches and electronic torque control, they are a reasonable alternative to conventional automatics, and help manufacturers cost effectively meet their CAFE targets. However, I seriously doubt they are as robust as a well designed, conventional, automatic transmission.
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Re: Continuous Variable Transmissions

Post by LadyGeek »

Next opinion-
Browser wrote:I prefer the one that doesn't break. When they start putting CVT into Lexus, Infiniti, Acura, BMW, and Audi brand cars and the like then I'll start believing this is as reliable and performs as well as gears. Wonder why they don't?
That's a valid argument, but I suspect it's more to do with keeping a heritage design rather than forging new ground. You don't change a major design feature because the underlying technology has changed.

Suggestion: Go research the car enthusiast (fan site) forums. For example, murano enthusiast - Google Search and read what they're saying. You'll get more open and honest opinions, including the bad stuff, than anything you read in a magazine or salesman you talk to.

It's like coming here for investing advice...
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Re: Continuous Variable Transmissions

Post by Browser »

Frugal Al wrote:
Browser wrote:I prefer the one that doesn't break. When they start putting CVT into Lexus, Infiniti, Acura, BMW, and Audi brand cars and the like then I'll start believing this is as reliable and performs as well as gears. Wonder why they don't?
Well, 2 out of 5 is a start: Infiniti started using them recently, and Audi has been using them in the A4 for a while now, albeit with a few well documented complaints.

I agree with NHRA, although conventional CVTs have gotten better, most designs have steel-on-steel power transfer friction surfaces utilizing steel belts and cones/pulleys that are not necessarily robust for heavy torque applications, and not inexpensive to replace (not sacrificial like a clutch). For moderate power applications, with judicious use of limit clutches and electronic torque control, they are a reasonable alternative to conventional automatics, and help manufacturers cost effectively meet their CAFE targets. However, I seriously doubt they are as robust as a well designed, conventional, automatic transmission.
Interesting. I knew that Infiniti put a CVT in it's smaller SUV for 2013, but not that Audi has been using them. What are the "complaint" about the Audi? Makes me wonder if the CVT is being used mostly to improve mileage and possibly because it is cheaper to manufacture. What about Subaru? They use it in the Outback and now the Forester SUV models (don't know about their other vehicles). They do give up some mileage in because of the 4-wheel drive and wonder if they switched to CVT to bring up the mileage on those? It sure improved the Forester mileage a lot in the 2014 model that just came out.
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Re: Continuous Variable Transmissions

Post by Browser »

Here are three issues raised about CVT I lifted from here:http://www.buzzle.com/articles/cvt-tran ... blems.html

- While improved acceleration and enhanced fuel economy are believed to be its strong points, some people have voiced their concern regarding CVT reliability.

- Cars with CVT do produce some noise when you try to accelerate. The car noise is produced as a result of CVT trying to adjust the engine speed. Though CVT mechanism allows the engine to rev at any speed, those who have driven such cars would have to get used to hearing sounds that seem like noise made by a slipping clutch.

- There have been complaints about jerky movement during initial acceleration or rattling during slow speeds.

I can testify to the last problem, as I noticed it especially with the 2013 Muranos that I drove and also to a lesser degree with the 2014 Subaru Forester. It may or may not be an issue for different individuals and it is probably something you adapt to after driving one for awhile. I personally didn't like it in the Murano but could probably live with it in the Subaru since it was less noticeable -- it gave me the vague feeling that the accelerator was loosely connected to the tranny in that vehicle when I first started up from a start but it didn't surge or hesitate like the Murano. I would check that out if you are test-driving a CVT-equipped vehicle.
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Re: Continuous Variable Transmissions

Post by Browser »

It's not too hard to find a lot of negative info on CVTs with a google search. Apparently, BMW has used it too -- in the Mini Cooper. A class action lawsuit was filed in NJ regarding problems with this transmission:
Law360, New York (November 30, 2011, 2:19 PM ET) -- A Mini Cooper owner launched a putative
class action in New Jersey federal court last week, alleging BMW of North America LLC concealed a
defect in the transmission of certain Mini vehicles that caused them to prematurely and
unexpectedly break down.
http://www.newjerseyclassactionlawyer.n ... efect-.pdf
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Re: Continuous Variable Transmissions

Post by Browser »

One other negative I read about:
To protect their relatively delicate belts, many CVTs require a special transmission fluid which is extremely expensive to replace. It also can require more frequent replacement than the fluid in traditional automatic transmissions.
Has anybody driving a CVT-equipped vehicle noticed this?
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Re: Continuous Variable Transmissions

Post by BigFoot48 »

The scheduled replacement of the CVT fluid the Ford C-Max Energi is every 150,000 miles. I don't think I will worry about the cost of this just yet.
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Re: Continuous Variable Transmissions

Post by ElJay »

I have to say it makes me laugh every time I hear a driver in a Subaru or Nissan with a CVT floor it and their engine just goes up to 5500 RPM and stays there. It's the weirdest thing. I would never buy one, and with conventional 8 speed automatics becoming the norm, I don't see any reason for CVTs anymore.
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Re: Continuous Variable Transmissions

Post by Jack »

ElJay wrote:I have to say it makes me laugh every time I hear a driver in a Subaru or Nissan with a CVT floor it and their engine just goes up to 5500 RPM and stays there. It's the weirdest thing. I would never buy one, and with conventional 8 speed automatics becoming the norm, I don't see any reason for CVTs anymore.
In drag racing, that is exactly what you want to do for fastest acceleration. You want to peg the engine at peak power RPM and never vary from that peak power RPM number. A CVT allows this peak power RPM to occur continuously, from start to finish, the goal of a drag racer. A geared transmission, even an 8-speed, is going to spend most of its time above and below peak power RPM as it runs through its fixed gears, which is sub-optimal. The CVT computer provides the skill of a top drag racer -- not that I recommend that. So that fixed RPM you hear is actually optimal for fastest acceleration. You have simply become accustomed to sub-optimal shifting.

Most of the time, if you aren't mashing the pedal to the floor, the CVT computer is optimizing for efficiency, not acceleration, but it can do both.
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Re: Continuous Variable Transmissions

Post by deanbrew »

ElJay wrote:I have to say it makes me laugh every time I hear a driver in a Subaru or Nissan with a CVT floor it and their engine just goes up to 5500 RPM and stays there. It's the weirdest thing. I would never buy one, and with conventional 8 speed automatics becoming the norm, I don't see any reason for CVTs anymore.
That's called efficient operation. Different doesn't necessarily mean inferior, you know? Are you seriously suggesting an 8-speed tranny is less complex and preferable to a CVT? The post above this one is on the money.
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Re: Continuous Variable Transmissions

Post by Jeff7 »

I've got a 2012 Subaru Impreza. I got that after having owned a Hyundai Elantra for more than 10 years; it was also an automatic transmission car, 4 speed I believe. I never did too well on manual transmission cars - couldn't get the hang of the clutch, and most of the time I'd stall a car if I tried to get moving from a dead stop. If the car can figure out how to shift more effectively than I can, I had no problem allowing it to do so. :)

I'm pretty ok with the CVT. The coasting aspect is something I don't like - I can slow down pretty effectively just by letting off the gas pedal. It doesn't do much to let anyone behind me know that I'm slowing down though, since hitting the brakes would slow me down too much then. It didn't take long to acclimate to though.

In terms of getting going, it feels snappier than the Elantra, with some decent get-up-and-go, and smooth acceleration.

The cruise control also does a good job, even on hills. It gradually adjusts itself when going up, and it also engine brakes on downhills, though it's still not perfectly good at maintaining a speed, so you'll want to use your brakes. The Elantra would drop up to 10mph when hitting a hill, before it would finally downshift to maintain the set speed.

It's got paddle shifters too, so if you feel like offering shifting suggestions to the car's computer, you can use those. I say "suggestions," because if the computer doesn't think your assessment is accurate or safe, it won't allow it. You can still shift over to the full Manual mode then, and at that point, the paddle shifters are fully in control. (Though it still might not let you do something like shift from 6th to 1st while doing 60mph.)
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