Steptronic....... so what's that then?
Slinky Little Fox has a Steptronic gearbox which is not what you would call a common feature amongst MG's. It is a Continuously Variable Transmission (CVT) gearbox - which means essentially there are not any gears!! The car is often incorrectly referred to as an automatic - which it is not in the conventional planetary sense - although it can hardly be called a manual either!! It is missing a clutch pedal and is easy to drive around town, so I can see why it gets referred to as an automatic.
History
MG first introduced the Steptronic model as part of the model year MY2000 range. I have never been able to find an accurate history of its introduction but have found plenty of speculative reasoning. That, partly, is why this section is included. There has been smoke that BMW bought the MG company for use of its Steptronic technology. An argument that supports this is that when they sold the MG group they retained the copywright to the Steptronic name. Henceforth all MG's, especially the MGTF, were sold with the new name Stepspeed. All BMW's, especially including the Mini range, are still sold as Steptronics. BMW retained quite a lot of copywright names and I suspect that they are classed as intangible assets.
I personally do not agree with this for a few reasons. Firstly BMW had enough cash to complete some serious research and development if they were desperate enough - perhaps this was merely a marriage of convenience and timing rather than exclusively wanting one particular part of a car. Secondly, and more logically, the gearbox was not made by MG but by a CVT specialist: ZF Engineering. Although it has been noted that the CVT VT1 was developed in partnership between MG Rover and ZFST, from this I would infer that it is a bought in product.
Performance
It is quite a quick car, as a result of near perfect gear changes - in that there really aren't any gears! Original tests show the Steptronic as having the slowest accelleration, by a small margin, in comparison to other models. Two immediate reasons for this are that the standard 1.8 mpi engine was used, and that the gearbox is heavier than a manual. As such it does not accellerate from 0mph as quickly. That said better gear changes mean that the car probably accellerates faster when already moving - which is very useful around all the twisty bits. To explain, although I have always prided myself on my gear changes in a manual, I recognise that I would never achieve the accuracy delivered from the CVT. This has not bothered me as I don't take part in drag races from a standing start, and require the quicker accelleration in real life driving. This is of course all unproven as I do not race other cars on public roads officer.
So is it any good? Well it is a robust bit of kit, and the electronics prevent you from doing any damage to gearbox / engine by limiting your journey to the redline at the right place.
So is it safe? Well you have both hands on the steering wheel for a greater percentage of time than with a manual gearbox. That equals more control, more assertive driving, so in a word...yes.
So would you like it - automatics aren't for sports cars are they? Well long gone are the days when automatics were considerably slower and more sluggish. If you have the perception that automatics don't belong in sports cars then you probably won't like it. You will probably find the paddle shift gears fun at first, but tire of the novelty easily. If however you don't mind moving with the times I would say that it is an improvement - a lot of sports cars have this functionality these days. In fact didn't Porsche introduce the Tiptronic way back in 1987? Oh and as I mentioned before - it's not really an automatic, it's a CVT.
OK so this is the interesting bit and the driver for this webpage. On my mission to find out out the gearbox works I found that there was not much reasily available information due to its exclusiveness.
There is no point in me reinventing the wheel - or the gearbox for that matter. I will give you a quick explanation, but the real meat is found in the documents linked below. If you find out any more information on the CVT please let me know and I will add it to this library. Click on the link to email Jonny_WoW
The gearbox has 3 driving modes: Drive (for normal driving), Sport (higher revolutions for faster accelleration), Steptronic (six speed manual simulated progression). Manual progression is completed by shifting forwards on the gearlever to progress up gears, and backwards to progress down gears. This can also be achieved by use of paddle shift levers on the steering wheel.
The gearbox model number is VT1-T and (as far as I can tell without seeing them side by side) is essentially the same as the VT1-F found in other marques. Information on the VT1-F is more readily available and used for reference below. The obvious difference is that manual shifting is reversed to the VT1-T.
CVT is achieved by a steel drive belt moving between two diagonally positioned steel conical "V" shaped pulleys. This allows different geraing ratios without stressing the steel belt.
MGOC Steptronic review
ZF.com (manufacturers website).
ZF.com (manufacturers description of VT1 CVT).
AEI MGF Steptronic review
VT1-F description by ZF Getriebe (Manufacturer)
CVT explained
Engine Management System description - props to Dieter.
How CVT works
CVT FAQ - acknowledgement to Mini2 forum
How CVT works
ZF gearbox description - acknowledgement to Mini2 forum
ZF Gearbox description - acknowledgement to Mini2 forum
Interesting concept...reversing the manual direction.
Glossary of terms:
MEMS3: The Modular Engine Management System Version 3
CVT: Continuous Variable Transmission
ECM: Engine Control Module
GIU: Gearbox Interface Unit
SMG: Sequentially Manual Gearbox
Links to other pages on this site
