A Detailed Assessment of the CVT Transmission

Sections: DIY | MF Feature May 21st, 2004 21 Comments

We recently received a very detailed technical brief from John Ewald that explain in detail the functions and capabilities of the MINI CVT gearbox. The PDF weighs in at 31 pages and 1.4Mb in file size. You can download it here. The following is an introduction:

An enthusiast community is growing up around the CVT-equipped cars. There is natural curiosity about how each of the onboard components integrate with others in the MINI Cooper CVT, and interest in how each the devices actually function in the cars.

With cooperation from ZF Getriebe N.V. Sint-Truiden (Belgium) we have this very good mechanical description of the Continuously Variable Transmission now available.

MINIUSA and BMW Group have answered some of the questions it raises. We should now be able to pull together a much better understanding of this very capable gearbox, the heart of our Cooper CVT.

The ZF ecoTronic VT1F Gearbox is used in the MINI Cooper CVT and MINI One CVT. It is simple, reliable engineering married to powerful computing and controller software to produce a very capable car with the flexibility to meet more driving situations than any single gearbox. There are three forward selections: Drive (D), SportDrive (SD), and the virtual-manual Steptronic (1,2,3,4,5,6), as well as Reverse (R), and Park (P). The CVT replaces all the complexity of gears and layshafts used in traditional transmissions with two hydraulically-controlled variable-diameter pulleys (variators) and a metal Van Doorne pushbelt to produce turbine-smooth acceleration, and better economy and performance than a standard automatic. The manual mode is strong and precise enough to permit throttle-steering in track day driving, and still flexible to drive in commute traffic without shifting.

Owners are enthusiastic about their CVT-equipped MINIs!

A dedicated Forum was established on MINI2.com to explore the character of these cars and to share experiences and ideas. This group found all manner of details on the gearbox and develops driving technique suggestions to wring the most from this CVT package.

A big thanks to John for all the hard work he's put into the document and all the people that have helped him along the way.

+ PDF Link / MotoringFile

Written By: MF Staff

Vanwall
As an enthusiastic CVT owner, I'm very happy with my MINI. I can have a manual shift mode for the twisties, where my MINI keeps up and more, thank you, (could it be me? – Naw!) or a smooth, relaxing drive in heavy traffic with no clutch pedal dancing for stop & go, or when in the “D” mode with the cruise control set, I get quite respectable mileage. It seems reasonbly bullet-proof as well, day in, day out, and the manual shifting is unchanged over the 45K miles I've put her through.

Early on, right after the break-in period was over, I went out on weekends to some of the empty, sprawling industrial parks near San Diego and experimented with the various modes of the CVT. I worked out a lot of personal preferences for driving the CVT, which is very sensitive to driver input, frankly, and came up with the 1-D-SD “Flick”, a take-off tecnique, and also found that the CVT has engine-braking effects on downshifts that are very useful on the twisties. Left foot braking seems to be the ticket for quick driving in the CVT, so I'm in training! I'm a hard-core CVT MINI driver, now, without a doubt, cause it's not like the others!
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        BCNU,
      Rob in Dago
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John

Here's a few technical details that may add to reading the Description, and support to Rob's comment.

In Steptronic Manual with enough throttle applied to accelerate through the “gears”, the computer will automatically upshift at 6000rpm (1>2, 2>3, 3>4, 4>5, and 5>6) very precisely. Engine is limited to 6000rpm, also called the redline which is now displayed correctly on the tach in v36.0 or later software.

This redline is not actually an engine-required rpm limit. The input shaft speed maximum of the ecoTronic VT1F CVT is 6000rpm. The engine redline is actually 7000rpm as used on the 5-speed Cooper or One. The EMS2000 computer limits the engine to 6000rpm using a combination of retarded spark (first to happen, and near instant response) and fuel (absolute effect), but it's applied to the system after maximum power from the motor.

Interestingly, the EMS2000 computer limits the bottom of the rpm range in each “gear” as well. An automatic downshift occurs at 2000rpm for 6>5, 1800rpm for 5>4, 1600rpm for 4>3, and 1400rpm for 3>2. Steptronic 1 must always be manually selected.

No upshift or downshift will occur, even if manually selected, if the resulting engine rpm is outside of these logical limits set by the computer.

All of these computer-monitored limits are what produce the near bulletproof fun and reliability we enjoy with these cars!

It is possible, from the driver's position, to pick the Selection (D, SD, or Steptronic) and the Mode (CVT, or stepped Automatic Transmission simulation) to fit the driving situation exactly just as Rob stated above.

The computer stays out of the way, in Steptronic, to allow a great deal of manual control if that's what the MINI CVT driver demands. The ZF gearbox holds a gear ratio tenaciously unless either of the rpm limits for that selection are exceeded. It is entirely possible to throttle steer the MINI through corners on the track. That's about as “manual” as it gets.

Fun factor rising. A wonderfully versatile and reliable machine!
Lee

I borrowed the dealershipÃ¢â‚¬â„¢s CVT demo while waiting for some work on my car to be completed. I got to spend a few hours with the car driving through hills in upstate South Carolina and around the city streets of Greenville.

In brief, I very much liked the car. I live (and play) in the mountains of western North Carolina and donÃ¢â‚¬â„¢t want to give up either the 6-speed transmission or the supercharged engine, but I spent enough time with the CVT Cooper to believe that it would be a superior car to mine if I did much commuting in slow or stop-and-go traffic. As Rob and John say, itÃ¢â‚¬â„¢s no slug; the transmission chooses an appropriate ratio and does so very quickly.

The engine speed quickly increases, then stays at a constant rpm as the carÃ¢â‚¬â„¢s speed increases. This effect is different from either manual or conventional automatic transmissions and I am told that it causes some drivers to believe there is a problem with the transmission when there isnÃ¢â‚¬â„¢t. But I quickly got used to it.

Congratulations to ZF for developing such a fine transmission and to MINI for choosing it. Based on my admittedly brief experience and what IÃ¢â‚¬â„¢ve read on the board, IÃ¢â‚¬â„¢d have no problem recommending the CVT.
Lucas

My first MINI was a CVT. Unfortunately, I cannot attest much to its advantages. Perhaps I am partial to stick shift. I can say, however, it was super cool and real nice for casual driving. However, my experience wasn't so smooth.

First the good points. I like how well the CVT complemented the engine during normal acceleration in that it achieved optimal performance/economy ratio. I can actually accelerate faster with the CVT than shifting through the 5-speed that I now have.

Unfortunately that is where the good points ends for me. The worst part of the CVT for me was the fact that the dealer had it replaced 3 times and still could not fix a recurring problem of the car shaking at stand still. Other than that, as a relatively aggress driver at times, I feel less control of the throttle and the gear ratio the car uses to drive on.

The CVT somehow always wanted to use a lower gear than I prefer — yet I had no control over it other than to force it using the autostick. Perhaps it is simply a matter of taste — I had similar problems with BMW's automatic transmission.

It is also hard to get used to the delay in engagement from stop. I drive more than one car during the week and frequently forget to wait till the transmission to engage before applying more gas — which then results in the jerking sensation of the CVT kicking in.

But these are my personal experiences. I have heard lots of people who had much better experience. Perhaps my driving style is simply to antiquated for a sophistocated CVT. :-)

At any rate, having the CVT is nonetheless a marvelous achievement for MINI and will give some driver some ultra refined driving experiences and simply annoying for others.
Linda Crow

One should carefully consider buying the Mini with the CVT if you ever expect to resell the car. Even if you readily adapt to the differences in feel of the transmission over a standard automatic transmission perspective buyers may not. We have taken our Mini to CarMax (you would think they would know better) and they insist that there is a problem with the transmission slipping even though we had it checked out by two different dealerships.
hadi ghasemi

please send me a catalog about cvt transmition and varumatic gearbox with its details. thanks.
http://mechanics81.persianblog.com Ahmad Rafsanjani

please send me a catalog about cvt transmition and varumatic gearbox with its details. thanks.
hosseinjannat

hello new cvt gearbox design by gears I have patent of this gearbox
Dan

i thought cvt was available only on nissan and mitsubishi
R.L.Werre

I have a CVT patent(US Patent Number 5800302)that dosent use the unreliable hi matenance pulley and belt. It dosent have other problems such as a delay on take off. It uses Two sets of planitary gears so its simple to build and verry reliable. It would also work well in conventional or hibread veacles including large trucks. let me know what you think. (roger.werre@sensor-tech.com)
Andrew

Could anybody tell me the gear ratios of the ecvt gerbox when it’s in steptronic mode?

Thanks

Dan Gaines

Hey!

  Can anybody help me! I have no problem with the CVT, but no one seems to have the answer to it's longevity. The dealer and MINIUSA have no idea how long it will last. I did find out that they do not repair them, just replace them at 3,000 dollars. Can you get 150,000 to 200,000 out of the CVT?

Dan

peyman

I am B.S student of semnan univercity of iran . My country the equipment of libraly and serch is very less. I am study about CVT gear box. I need information about this CVT gear box. If you can, please help me. Tank you a lot. the best Regard.
amin
informatoin of “CVT GEAR BOXS”is works
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           "thank you"
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kosala

i want to know more about cvt automatic geraboxes and what will be the future development of them.
ravikumar

i want to know more information about valve body of cvt gear box
http://www.carz4me.com Avinash

I am quiet curious regarding CVT. Can you provide a fuel effeciency comparison, comparing the normal transmition of a car and the CVT transmision installed on the very same car.
chris w

I’m curious if everyone that posted their happiness early on about the CVT Transmission is still in such high spirits! Please reference the complaints on

http://www.consumeraffairs.com/automotive/mini.html

My wife and I were considering a mini with CVT but ane no longer interested after reading the masses of repetitive complaints.

Anyone with comment can also forward to me @ VWS4Life@aol.com

-CW
Pingback: MotoringFile » Archive » Nissan Doubles Warranty on CVTs Due to Mechanical Failures
http://www.facebook.com/kholsapple Kathy Holsapple

Thanks for listening. my question is, does it hurt my CVT transmission by just driving in “D” all of the time? I don’t drive heavy freeway miles and use it mainly for errands, short drives, etc.

I’m new to MINI. It’s a 2005, I’ve owned since January of this year and don’t really understand the other driving modes. I just want to know if being in “D” continually, is harmful to the transmission.
Andy L

Guys – all i can say is read the web, the quality of the CVT is called into question and if it does fail (which it has !!)you are faced with a $10,000 fix that wont be covered – there are plenty of people out there that will testify to this fact, its a straight replacement!

The problem manifests itself with knocking on cold starts increasingly getting worse over time. Few parts are availale to fix the problem – thats if you can get someone to do it – BMW wont.

In many cases pople have been left wondering about scrapping a car that is less than 10yrs old. As a driver and enthusiast of german cars and engineering the <2004 minis are to be avoided!

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