I think it has been said on this forum that these are not truly tried and tested yet. Lots of manufacturers have had problems with them.A honda is likely to be reliable, but the technology is not proven yet.
If you do a forum search you should find some past threads on them.
I first drove a CVT equipped car in 1989 - a Fiat - and was immensely impressed with it, despite the considerable buildup of revs initially from a standing start.
Unfortunately, however, the Great British Public never really took to the idea even when Ford offered it or when more powerful engines could be linked up to the technology.
By the way, the first patent for a toroidal Continuously Variable Transmission (CVT) was filed at the end of the 19th century and, in the 1930s, Austin produced a version of this CVT for 600 York cars.
The DAF version and later Volvo offerings are mentioned here (this is the type IIRC was in the Fiat I drove back in the late 1980s):
Nissan changed the Micra automatics from CVT to the ordinary torque converter variety. My hand control friend has had both sorts and says the new one is better to drive, but just wonders if durability was a factor.
the problem with cvt is the belt reliability, the punto probably isnt pushing the envelope here, and 50K isnt a big mileage. How long they last on big cars is a different matter.
shamless plug for a UK company - torotrak, with a reliable high torque/power capable ivt box using toroidal discs rather than belts. Deals signed with aisin, getrag, etc, testing done with Ford, Land Rover etc. Boosts fuel economy ~20% compared with 6 speed auto. Going to be used in Tractors as well.
Has some fancy tricks that allow high performance, hill descent/climb etc. www.torotrak.com
I've been wondering... why do they install a rev counter in a car with a CVT box ? Correct me if I'm wrong here, but the engine always keeps its revs at the same level, doesn't it ?
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I am the only Pole over here.
Can someone explain the difference between CVT and "conventional" autoboxes?
And before Dalglish comes and says I can find the information myself, I could, but I'd rather have someone I 'know' explain it to me in terms I can understand. I thought CVT was super duper but that comment about Micras has confused me.
(Bear in mind, I only found out a short while ago what a torque convertor was).
Here's my attempt to answer your question - it's a huge subject though...
A conventional automatic has a finite number of ratios. Instead of a clutch* there is a torque convertor. When in neutral, there is no connection between the input and output. The torque converter is a really clever bit of kit - it increases the flexibility of the gearbox to the extent that it is reckoned to give the equivalent of an extra ratio.
A CVT allows a stepless change between ratios, there are, in effect an infinity of gears. This raises the possibility of having a geared neutral. This can give immense problems for the design of the rest of the downstream drivetrain because at very low ratios, the torque can be massive!
There are many competing CVT ideas - not surprising really because the possibility of always being in the best gear, for either acceleration, or economy depending on driver demand is worth the cost and effort to develop.
I applied for a job at Torotrak in Leyland a number of years ago. For a number of reasons, none of which being suitable for publication, I decided against. It will be interesting to see if their technology ever becomes as popular as the idea itself deserves.
I have just read about a new (to me at least!) idea to have a CVT with two parallel load paths through the transmission, one via gears, the other via a generator/motor pair. I think this has real potential because it is not reliant on any rolling contact used for transmitting power.
If the rolling contact slips significantly, then the typical CVT rapidly becomes an efficient rotary friction welding machine!!
The transmission of power via a fictional contact between two metal parts is never simple - think leaves on the line!
On the original subject of durability..As others have said, the CVT has been around a long time. In 1908 Rudge motorcylce co entered a CVT-geared motorbike into the TT - it used a leather drive belt and a hand-operated linkage to vary the diameter of the rear pulley. In the 1920's several German companies exterimented with CVT's using metal belts and they were used in textile factories (to take drive off spiining shafts running through the mill). Then of course there was DAF...
The basic problem with the CVT is that it relies on friction to transmit the power. This is OK at low power & torque levels, but at higher powers then duracbility can be a problem. Once any slip sets in, a lot of heat is generated and the thing wrecks itself in short order.
GM have had a CVT plant in Hungary for some time, but production has been very slow in coming due to problems with the tranmissions. Similarly the Ford/FIAT plant produced transmissions that were bedevilled with durability problems. The ZF unit used in the Mini is also proving troublesome and many owners are on their second or third transmission (this is a problem in the US, where many Minis are ordered with auto option).
Personally I wouldn't buy one.
My posts must be invisible again. I will try again.
Does Honda manufacture its own CVT?
Is the Punto still available with CVT?
Yes, Honda manufactures several CVT's of its own design. The 'Multitronic', with multiplate clutch is the one used on UK market vehicles, IIRC. Certain aspects are (I believe) still under patent from Van Doorne so I think they buy in some components. Certainly the drive belt looks the same as the one used on the Nissan/Subaru Hyper-CVT.
The Nissan/Subaru is a kind of CVT+tiptronic function. The major components are made by Fuji (parent of Subaru). Nissan also make the excellent Extroid CVT which uses rollers rather than a belt - definitely the way to go for higher output engines.
The FIAT SpeedGear looks very similar in design to the Nissan/Subaru unit (it may even be that unit made under license). The SpeedGear is still being produced - don't know whether it is available in the UK.
Sorry, I was wrong. The Honda CVT is called Multimatic, Audi's is Multitronic. The Audi system is a little different in that it uses a segmented chain-belt with small 'pins' sticking out to give increased torque-transmission capability (that's the theory, anyway).
The Multimatic is the standard transmission on the Honda Jazz/Fit in Japan. There have ben a few reports re the oil-bath clutch, but these sem to have been few. The only "factual" info I hjave seen is this:
"Yes, this is why it's also called the 'start-up clutch'. Failure of the start-up clutch has become a sort of a 'legend' around the ASEAN region, because of rumours originiating from a few cases. In Malaysia for e.g., the rumours are flying around so heavily that the outsider might be forgiven for thinking that the CVT gearbox is a design failure but when I checked with Honda Malaysia for e.g., they reported less than 20 warantty claims for Jazz and City combined. This is from a total of around 20,000 units sold."
from this thread: www.vtec.net/forums/one-message?message_id=380654&1 on "The Temple of VTEC" site. Good information on the Jazz engine etc: on reflection, more than enough!
CVT's can be coupled to the engine using one of three techniques: electromagnetic powder clutch; conventional friction clutch (wet or dry) or hydrodynamic coupling (some kind of torque convertor). Nissan have used all three at some time or other. The problem with the TC is that it is diffiult to completely 'uncouple' it, so there is always some creep.
I have an A6 2.5TDi CVT (so not a SMALL engine) and it is superb.
I have done 63,000 miles in the car and no problems. Fuel economy is as good as the manual, as is 0-60. CVT suites a big diesel as it smooths out the narrow power band. If you want to get going you just hit the accelerator and the revs rise to peak power/torque (2,500 - 3,000) and the car just goes faster and faster until you back off. No jerks or jumps, no trace of down or up shift.
The only minor grumble I have is that when pulling of from standstill there is a little hesitancy that you don't get in a regular auto, but I just learnt to drive around it.
Re the comment about there being lots of revs when pulling off; not with this combo of big diesel/CVT. Unless you are racing away the revs don't get over 1500 in town traffic when pulling off, and even on the motorway rarely get over 3,000 (except for the odd Italian tune up)
HJ, Ithink you are mistaken about the X-Trail being CVT. I run both a Honda Jazz auto (CVT-7) and an X-Trail auto. The Jazz runs most of the time at pretty constant revs. The X-Trail on the other hand performs like a conventional auto (of which I have owned several, the revs rising and falling as it goes through the gears. Also it has a switchable overdrive very similar in use to a Volvo I ran a few years ago with an Aisan Warner 'box.
Both autos are excellent in their different ways. I am fairly confident about the azz CVT because it is a Honda.
What do people think of the engine note of cars with CVT transmission? I imagine it is strange never feeling the car 'drop' into top gear as in a conventional auto. Using an endless surge of forward motion then presumably trailing off, do the revs drop down when you reach higher speeds?
It doesn't sound very 'relaxing' but perhaps is more subdued in diesel applications. I have recollections of the Fiesta CVT efforts of Ford in the 90's with their constant revving engines akin to a slipping clutch.
When we tried the Jazz CVT, the engine ran at peak torque (about 2800rpm) and was very different to the old Daf thing! Seemed to pick up easily, with 3 aboard. If you want, you can select the 7-speed gadget and flick up and down to our hearts desire. Apparently it will also run in a similar way to a conventional auto box if you don't want to use the paddles: shifts among the 7 choices according to throttle setting. Didn't bother with that.
We're seriously thinking of a Jazz, but need to try the ride out for an extended period. Most of the roads here (Ribble Valley) are twisting, lumpy, and off-camber, all at the same time.
We, until recently, owned a Volvo 440 CVT. When they're working corectly they're good to drive (economical and relatively fast). However they're not reliable gearboxes as they tend to shudder (and sometimes stall) when moving from P into D with your foot on the brake and when coming to a sudden halt eg lights or junction. I gather Ford used a similar gearbox in the Fiesta and Escort in the 90s and gave up because of the repair costs.
They're not thought well of in the trade ("not a proper automatic is it" etc).
We were considering replacing the Volvo with a Honda HRV CVT. When I rang to make enquiries I was told that all the HRVs with this box had had recall work done and were OK. Even though it's a Honda I would question the longevity of the box.
Unless you really prefer the driving characteristics of the CVT over a conventional 4 speed auto I wouldn't bother until long term reliability of these new CVTs is known.
Regarding how can you tell CVT, it usually doesn't have 1 and 2 on the box, only D and L. When driving, the revs bear no relation to road speed and the box does not change up when you put your foot down.
It's because you're removing the default ">>'s" that automatically get generated when pressing the "quote original message" button and substituting in your own. For reference, by putting the 'less than' symbol at the start, and 'greater than' symbol at the end makes the words you've quoted invisible in this forum.
I'm coming to this late after a week away (church choir exchange trip to the Seychelles - lovely!).
Mine (A4 2.5 TDI) has been fine from new to 27,000 miles apart from an occasional slight juddering when starting from rest. I mentioned it when it went in for service last week - it had stopped doing it (naturally - from the day when I booked the service!) but they (Aston Green Audi, near Slough - very good and thorough) said there was a minor fault detected and they would have another look at it. They also said that there had been some problems with multitronics - I will find out more.
I think someone has said already in answer to a previous point - that you can tell a CVT transmission by there being no rising and falling of revs as there is no gearchanging. That doesn't men that the rpm stay constant, though: the revs rise gently with acceleration.
Is the 'electromagnetic powder clutch' (see above) the same principle as the magnetised iron filings method used by the Smith's Easidrive (I think) transmission occasionally seen in Rootes Group products more than 40 years ago?
Until the tinworm claimed it, we had a Metro 1.4 CVT as a run-around inherited from my Grandfather. It did 114,000 and the gearbox never had a problem, I'm not sure exactly what kind of gearbox was in this car?
As for the Micras with the powder clutch, my father has one and it seems that at some point they all have a problem with the magnets in the gearbox that may cost around £800 to fix.