Dog and Lemon was getting all over excited, not me. I merely warned readers to keep their ATF up to the mark and change it every two years.
Audi's CVT problems have mainly been with the clutch system. The old 6 plate clutches can be replaced by 7 plates relatively cheaply on the same shaft.
HJ
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As a matter of interest, which are the CVT boxes to avoid, and which are OK?
As far as I know, the Honda CVTs are OK. I believe the Nissan ones are, as well. Not sure about the FIAT box.
Any others?
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I wouldn't buy one again.
We had a 96N Volvo 440 with a CVT. The jerky gearbox which stalled ruined a perfectly good low mileage car.
With regard to current ones I would be more interested in hearing long term owner's views
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The Nissan CVT boxes have low towing limits compared to conventional autoboxes and manuals - that gives a clue how good Nissan engineers think it is.
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The Nissan CVT boxes have low towing limits compared to conventional autoboxes and manuals - that gives a clue how good Nissan engineers think it is.
But the Nissan CVT boxes are only fitted to small cars, are they not?
A CVT with an electronic clutch (such as the Honda one) is much better for fuel consumption with a small car than a torque convertor automatic. No losses, and the car is always in the right gear ratio.
So far, it seems the Volvo CVT is no good. The Honda one I know from experience is fine.
Any others?
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>> A CVT with an electronic clutch (such as the Honda one) is much better for fuel consumption with a small car than a torque convertor automatic. >>
But isn't the torque convertor gearbox the best one to go for for longevity? Particularly if the regular driver is not especially mechanically sympathetic (no names, no packdrill).
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But isn't the torque convertor gearbox the best one to go for for longevity?
SNIPQUOTE!
Well, I don't know - that's why I was asking. Are there CVTs which are as long lived as TC automatics? If so, who makes them? And who makes the ones to avoid?
Edited by Dynamic Dave on 27/11/2007 at 19:07
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Although we have only owned our Audi A6 1.9TDI SE Avant for 6 months, the 6 speed Multitronic transmission is very good. It has two modes (drive & sport) in automatic and two ways of manually shifting (with the 'gearlever') or buttons on the steering wheel. Its great in town in auto mode and also on country lanes where you can shift manually.
Long term we'll have to wait and see. The car has done 69k without any problems that I know of. I think the transmission is of the CVT variety as the is no torque converter to check/fill. Maybe I should check the Audi forum re the longevity it!
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The Nissan CVT is fitted to the new X-Trail, whether you consider that small depends on your point of view.
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I believe the Nissan Murano is CVT only as well (unfortunately)
Honda used to fit a CVT to the HRV.
The unit in our old Volvo was the old DAF variatronic IIRC - no longer made. I think Volvo currently use normal torque converter autos (but am happy to be corrected on this)
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The Nissan CVT is fitted to the new X-Trail whether you consider that small depends on your point of view.
No, I wouldn't consider that small - but surely it's too early to say what the longevity is on such a new model?
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For a list of cars that use CVT see:
www.lasercannon.com/cvt.htm
and for all the information you ever need for the latest gearbox technology see:
www.toomonline.com/gearboxlinks.htm
I own a C-Max CVT auto, which is a diesel. This is a world away from the Daf variomatic - which I drove in the eighties and was good fun, but not unrefined.
A CVT offers better economy than a torque converter automatic and the C-Max is extremely smooth and relaxed. The gearbox is constantly trying to select the highest gear possible and since the diesel produces its torque at low revs, you're doing low revs nearly all the time.
The C-Max CVT also uses a torque converter so you still get "creep" when letting the brakes off, but this is locked up once moving and it also releases when stationary in traffic to reduce fuel consumption.
The only problem I have with the C-Max CVT is that there is a slight delay in take up of drive when pulling away from a standing start, which needs a change of driving style - you have to plan a pull-away rather than taking a dive.
CVT's are probably less durable than old technology autos - but in development of the C-Max several cars were given 150,000 mile real world tests without a failure. Used and maintained properly there's nothing wrong with them in my view.
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No I wouldn't consider that small - but surely it's too early to say what the longevity is on such a new model?
Maybe, but Nissan themselves have set a very low towing limit for the CVT, compared to the manual - as the X-Trail is often bought by caravanners, Nissan's engineers obviously aren't sure.
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There are two seperate issues.
1. How the drive ratio is determined (nowadays usually a segmented metal push-belt or disc)
2. How engine power is coupled to the drive system (powder-clutch, hydraulic clutch, torque convertor etc).
(2) is not really that important - its more a matter of preference.
(1) is the problem. CVT's generally rely on power transfer via friction through a very small contact area (e.g. between a curved disk and a flat plate; or the edges of a metal belt against a pulley).
In order to avoid any slip the clamping force per unit area must be VERY high - and hence the control system to achieve this must be very precise. If anything goes wrong, or the fluid becomes contaminated, then slip occurs and heat build-up is extremely rapid, resulting in melting, shedding of swarf which wrecks the rest of the hydraulic system etc etc.
There have been many 'false dawns' with CVT's (remember, they were first used in 1908!) and lots of people have had problems. The CVT fitted to the Mini is now on its 52nd revision, I believe, with many changed under warranty. I've also heard that Audi dealers tend to turn away multitronic problems if the car is older than 3 years (my mate who's a transmission repairer has had a few Multitronic owners 'sent to him' by the local Audi agent - he sends them to another repairer!).
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Did DaF variomatics wear out fast Aprilia? I drove a late one with a Renault 4cyl engine, not the original flat twin... It made a charming whistling noise on the overrun sometimes, and seemed to work fine. Of course it wasn't a sporting device, or a particularly refined one, but it had a certain charm and wasn't all that thirsty or all that slow.
Come to think of it though it had become a Volvo by then. But it was a DaF all right.
2nd edit: I guess the conclusion to be drawn is that CVT is best with cheap easy to change rubber belts and low-powered engines.
Edited by Lud on 27/11/2007 at 18:40
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I didn't have much to do with DAFs at the time they were popular, but I do recall that the rubber belts were not that easy to change (long labour time IIRC). I guess they were OK for use with 40bhp engines in countries without any hills.. ;-)
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I had a DAF 55, which had the 4 cyl Renault 1100cc engine of 55 BHP, and found it very comfortable and surprisingly quick, particularly up local hills where my previous manual car had really needed an extra gear between ratios.
I found that drive belts needed adjusting fairly often, and eventually the centrifugal clutch needed re-lining.
A few years later I had the modified version (badged Volvo 66) which seemed a few hundredweight heavier and thus more sluggish in spite of the extra 11 BHP they had from a 1300cc Renault engine.
I think that had a different clutch arrangement, but didn't keep it long enough to find out in detail. Drive belt adjustment was again a regular need, which finally put me off the design.
Current designs using steel segments rather than overgrown fanbelts to transmit drive probably don't need adjustment so often but replacement must be a pain in the wallet.
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Current designs using steel segments rather than overgrown fanbelts to transmit drive probably don't need adjustment so often but replacement must be a pain in the wallet.
Its a segmented metal belt driven in compression (forms a 'strut'). There is no adjustment, contact pressure is maintained by a complex control system. Any slippage will soon result in damage to the surfaces of the belt and pulleys and the box will need stripping and rebuilding. There are not many people with the training, experience and range of special tools needed to undertake this....
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having had a few CVT boxes in the family and made sure they had the oil changed very frequently and always at correct level i can tell HJ that this doesnt stop the belts snapping and wrecking the gearbox case
ill never have another one
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Re the auto box fitted to the new model X-Trail: the petrol uses the CVT box, but the diesel uses a 6-speed TC box which is only available with the 150hp engine, not the 173hp version.
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Then they've changed in the last few weeks - in October 2007, I specifically enquired about a diesel automatic X-Trail but discovered the CVT towing limit was way too low.
Perhaps Nissan have discovered that the CVT won't handle the diesel's torque.
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I run a Punto with CVT - known as the Speedgear in the Punto (formerly Selecta on Unos, I believe.)
Has been reliable on my low mileage (35,000) model, but that's with changing the ATF and filter EVERY year. Please be sure to use the appropriate ATF - some will try to say that Dexron III is o.k. - might be o.j for some, but for the Punto it HAS to be Tutela CVT Fluid. The Fiat technician wouldn't do it otherwise.
Reading various responses and Aprilla's consistently knowledgeable discussion of CVT, I am looking to get rid of the car. A total rebuild if things went pear-shaped would be in the region of £1600.
Which is worse for the metal, toothed belt, Aprilla - hard acceleration or 'high' speed (i.e. 70 mph)? I'd imagine that if the belt was weakened, high speeds could be worse?
AA
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I wouldn't dismiss Dog and Lemon out of hand. They are deeply cynical, and what they have to say about my 1984 XJ12 is very distressing. However, here in New Zealand is probably the ultimate long-term test of used Japanese cars. We've had used imports for over twenty years, so are well aware of long-term failure modes. If there are any high-mileage issues with CVT transmissions, you can bet we will see them first.
I've just bought a 1988 200,000 Km Mazda 323 for my daughter as a first car for the equivalent of UKP400. Very little corrosion, runs fine, everything works. Some routine servicing is now done, and it will probably be fine till 300,000 Km. The UK habit of trashing anything over 5 years old just doesn't fit here.
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It would appear that , as usual, the Japanese know how to build mechanisms which last.
Would the poster above who said he had several CVT failures care to name the make(s) of car which were involved?
Edited by pyruse on 28/11/2007 at 10:06
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Excuse my ignorance but do all the different CVT drive systems do that "engine revs do not rise with acceleration" thing? I've never driven one and always thought that must be so weird?
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It is at first.
SWMBO stated that it sounded like I was slipping the clutch. In the Punto the revs. do rise up to about 2500rpm as you accelerate (perhaps to 3500rpm if you hold it to the Axminster)and then go back to about 1800-2000rpm once you ease back.
AA
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Excuse my ignorance but do all the different CVT drive systems do that "engine revs do not rise with acceleration" thing? I've never driven one and always thought that must be so weird?
Basically they all do, the idea is to run the engine at optimum revs, either for torque/economy or power - but they can be engineered to use "fixed" ratios, like the MG TF steptronic.
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Excuse my ignorance but do all the different CVT drive systems do that "engine revs do not rise with acceleration" thing? I've never driven one and always thought that must be so weird?
Basically they all do, the idea is to run the engine at optimum revs, either for torque/economy or power - but they can be engineered to use "fixed" ratios, like the MG TF steptronic.
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And some of them have a 'sport' setting which keps the revs higher.
They do feel oddd at first, but you soon get used to them.
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