Slack in the 'box
BMW'S potent M3 SMG coupe has borrowed technology from the racetrack to let you sample the benefits of a sequential transmission. But, as Matthew Franey found out, it takes some getting used to
Permit me for a few movements if you will, to tell you something that you probably already know. It's a theory about driving and the reason that I - and probably you - derive as much enjoyment out of it as I do.
Driving is essentially a series of rather simple, unelaborate acts: you depress an accelerator, brake pedal or clutch, move a gearlever to or fro, turn a steering wheel left or right. Nothing too hard about that But choreograph these solitary little skits into one thumping rollercoaster of a stage show and you have, in my opinion, what the automotive experience is all about. It's living theatre - as enjoyable and involving a pastime as you could wish for.
It's also totally dependent, when done right, on every player remembering his lines and not missing an entrance. The times when an otherwise impressive car is let down by vague steering, soggy brakes or under-powered engine are too numerous to mention. Conversely, the times when a car surprises you with a superb transmission or acute handling are moments to savour. I hope, like me, you still get enjoyment from that perfect downchange or clipped apex.
It's for all the above reasons that I have a deeprooted suspicion of so-called driver aids. Anti-lock brakes, traction control, torque control devices are, in my opinion, all just the other side of nannying. And before you swell the postbags with cries of irresponsibility and "shame", I would be the first to thank my ABS in an emergency on a wet road. Yes, they are worthy safety devices that hold a vital place in everyday driving. And yes, I would turn them all off for those brief periods when I wanted to truly drive for the fun of it.
It's not that I'm some dyed-in-the-wool Luddite either. There are a great many technological advances in motoring for which I am grateful... honest. Power steering, cruise control, six-speed gearboxes. The point is, very few of them enrich the driving experience at its purest.
That's why the arrival on these shores of BMW's powerhouse M3 with SMG, Sequential M Gearbox, potentially heralded a genuine advancement in the kind of technology I like. The 'M' in SMG is the critical letter: it's `M' for the house of M, BMW's renowned motorsport tuning department, and most importantly 'M' for manual. For this is no Switchtronic, 'faux' automatic gearbox, this is a genuine six-speed transmission with its bloodline traceable back to the racing BMWs that graced the Super Touring divisions round the world. For the first time, at a reasonably sensible price SMG costs £1,735 on top of the £38,420 list, compared to Ferrari's £100,000 F355 with a £6,345 price tag for the paddle-operated F1-style system you too can play at being racing driver with a gearbox designed for the purpose of improving the show.
SMG works, like the Ferrari system, via an electro-hydraulic system, but unlike the Maranello contender, you change gears with a conventional centre-mounted shift lever rather than steeringwheel mounted paddles. A quick nudge forward or back on the lever operates the M3's electronic brain, which uses the hydraulics to operate the clutch and two further cylinders to engage the gears. BMW claims the whole process takes 0.25s from start to finish, with the system automatically blipping the throttle as you pass down through the ratios.
Purpose-built electronics keep a beady eye on your driving habits, delaying any gearchange that would cause the engine to over-rev and missing extraneous gears on a down-change if you are quick enough on the shifter to go from, say, sixth to second. Further sensors also detect the first signs of engine braking locking the driving wheels, automatically dipping the clutch to ensure that the BMW retains its balance mid-corner.
With the car taking care of the clutch for you, the M3 looks at first glance like an automatic - housing just two pedals in the footwell. It can drive like an 'auto' too, for SMG comes equipped with a self-selecting mode, allowing you to flick the lever across to the right at the first sign of heavy traffic. From that moment on, the M3 monitors throttle position, engine speeds, arid a host of other determining factors before changing gear for you.
On paper it sounds like a driving enthusiast's dream: a performance car with touring car innards, and the added refinement of an automatic when the realities of modern town driving come to bear, I don't know about you, but I have spent most of my driving life waiting for the day I can have the benefits of both systems in the one vehicle. BMW, it seemed, were offering it on a plate.
The decision to marry the SMG 'box to the M3 was an obvious one. BMW's modem sports coupe may not have the sort of cult following attributed to the old racing thoroughbred - the original M3 boasted the sort of super-sharp handling and steering that its sibling rival couldn't quite match - but it remains an accomplished ground-coverer. And while the later car tries too hard to be all things to all men, under the bonnet lies one of BMW M's great engines - the normally-aspirated 3.2-litre straight-six, putting out 320bhp and an effortless 2581b/ft of torque at a leisurely 3,250rpm.
Sequential gearbox or not, the engine is a delight, hurling you to bOmph in a shade over five seconds and pulling strongly - no, mightily - from idle to just shy of its 7,600rpm redline. Allied to this is the crisp, booming bark of the exhaust, a sound so seductive that the temptation to press on lies behind every red light or Give Way sign.
But pulling away from the lights in an M3 SMG requires a little getting used to. In manual mode, a tug back on the lever selects first gear no sign of clunking or perceptible drivetrain movement at this stage. Despite the lack of a clutch pedal, it is important to remember this is no automatic and the BMW will not engage the clutch plates until it detects some movement in the throttle pedal. Pull away on an incline and the handbrake remains a vital part of the process.
The take-up of the clutch is smooth and without drama, and with the six ratios closely spaced, the time to change into second is soon upon you. I wish I could tell you at this point that all my expectations were met and the reality matched the pre-launch hype. I wish I could tell that with a small, swift pull on the lever second gear was engaged and the car continued on its relentless way. I wish I could, because I can't.
Although the gearstick is effectively a 'fly-bywire' switch, the method for moving up through the box is surprisingly unwieldy. Pull back and release the shift, feather the throttle slightly and then - and only then it seems - do the selectors start searching for gear number two. I have no reason to doubt BMW's claim that the actual change-up takes just milli-seconds, but in all the racing sequential 'boxes that I have driven - admittedly nearly all with a mechanical linkage to the gearbox - and Ferrari's much-admired F355, the moment of gearchange comes the instant you pull or push the required lever or paddle. Not one, two or three tenths of a second later, but instantly.
It may not sound like a long time, but as my physics master used to delight in reminding me ad nauseam, at 60mph you are travelling at 88ft per second. In other words a quarter of a second after you expect the gear change on your M3 to have happened, you would be 22ft down the road, round a corner, away from the apex et cetera. It was a totally unnerving feeling to start, not dissimilar to that horrible moment when you go to overtake in an automatic and the kickdown seems to take forever to kick in.
Once the next ratio slots in, progress can continue, but in the whole time spent behind the wheel, the occasions when I managed a genuinely smooth change - the kind that in a manual gives you that satisfying feeling inside - were few and far between. The M3's 'box is at its best when taken to the redline, when a yank back on the stick without lifting the throttle will produce a lively - and smile inducing - shift that is as quick, if not quicker than anything than you could manage with a clutch at your feet, but at 'around town' speeds, the constant little jolts in the back become wearing.
Overcoming the delay in the SMG manual mode is, as BMW's technical people were at pains to stress, really all a matter of readjusting your driving style. A week behind the wheel of the car, they claim, and your whole mindset changes; doing things just that little bit earlier. But try as I might, I felt let down every time I changed down. The purpose of a sequential shift is surely to speed up the whole process of changing gear, not retard it.
Try hard to adapt to this new form of automotive 'lag', and the M3 will make headway with assured poise. The overall balance of the chassis is superb, although there is a slight vagueness around the point of turn in that would have made the original blush. Steering feedback is also positive, the broad Michelin tyres providing levels of traction under full power and grip under cornering that would rarely leave you wanting on the roads and scarcely in trouble on the race track, where most of this test took place.
Yet for all its fonnidable power delivery and sharp responses, the M3 was hard to drive in truly jaw-dropping fashion. Even through the undulating, adverse camber bends of Brands Hatch, the coupe adopted a constant tendency to understeer, however much throttle was applied in an attempt to unsettle the rear end. It's been a regular charge of the M3 since it adopted the current 3-series body and has never been fully rectified.
To see exactly how a sequential shift works at its best, you need to really hustle the M3 into a corner like Brands' Druids Hairpin at the sort of speed that moistens your palms, brake later than you dare, allowing the Herculean discs and ABS to do their job, and then just stab forward from fifth to second in three quick blips. The gear indicator set inside the tachometer registers your request and at last the change is as smooth as you could achieve with your best heel-and-toeing, the revs blipping the selected gear into place.
The beauty of a system like this is that it allows you to stop worrying about the things that can often go awry when you are driving fast. The opportunity for wrong-slotting a gear is non-existent, the chance of sliding off the asphalt under braking seriously reduced. Now you can concentrate on the job at hand, that of getting the BMW round the rapidly approaching corner.
That's why a sequential transmission in performance cars is the way forward and why I applaud BMW for answering the requests from its customers to provide a system that at first glance brings the best of both worlds to everyday driving. But would I buy an M3 SMG if I was shopping for the ultimate sports coupe? Probably not. Only when the market can provide a system that is as rewarding as a genuine racing sequential shift-system would I become interested. Until then I think I might just pop the car into 'automatic' mode and get on with it. And that, as I'm sure you would agree, rather defeats the object.
BMW's SMG may be a first for the '90s, but the self-selecting 'boxes are as old as the car
Today's automatic gearboxes have computer brains which could fly a space shuttle; yet the advent of paddle-shifting and sequential changes has made manual 'boxes hot again. It's the latest move in a long history of easy shifting.
Early pinion 'boxes were slow and teethgratingly noisy when changing. Professor Porsche's syncromesh mechanism made shifting much easier, but it only became universal during the 1960s. Epicyclic geartrains, as used by Lanchester in 1903, had the advantage of permanently engaged gearteeth, but were heavy and had restricted appeal until the Wilson pre-selector variation in the 1930s. Suddenly competition drivers could make rapid full-throttle changes just by stamping on the left-hand pedal — as long as they remembered whether they had pre-selected 'up' or 'down' on this pioneer sequential shift.
In inter-war France the Cotal 'box offered pushbutton electric selection of its epicyclic clutches, a costly but luxurious solution for propelling your Delage.
Daimler-Lanchester's fluid clutch used a pair of impellers in oil, allowing low-speed creeping, but it took the addition of a third set of vanes to transform this into the torque converter which, because it actually alters the torque ratio under load, provides a seamlessly variable drive. However, because its ratio range is limited, you still need gears, though fewer than for a direct drive 'box. Thus General Motor's pioneer post-war autoboxes had two or three gears where manuals had three or four. Today, of course, a Mercedes auto has five and some manuals six gears, something which would have been seen as an over-complex solution to an inadequate engine by those early engineers striving for long-stroke flexibility. At the end of this trail lies the goal of infinite gears, such as the DAF and later Fiat/Ford Selecta CVT systems, which have failed to take off.
Chrysler introduced its Torqueflite autobox in 1955 with push button dashboard controls but this was no more than the 'P-R-D' autobox choice more usually found on a shift lever, Renault used it in the 1960s too. Then Citroen offered its C-Matic system, a peculiar hybrid with all the disadvantages of both auto and manual 'boxes: it used a torque converter and three epicyclic gears, but you had to manually shift between them. All the slushiness of an auto without the convenience of self-changing action...
Those who wanted a manual 'box but found pressing a clutch pedal a mite onerous could buy a Porsche or a Simca with a vacuum servo clutch triggered by touching the gearstick; if nothing else it cured you of driving with one hand on the shifter. Today two-pedal manuals are making a comeback Saab leading the way with the sophisticated Valeo system.
Porsche has contributed two significant transmission ideas. In the mid-'30s it developed PDK, a double-clutch system for racing. During shifts the drive slammed between two separate clutches, reducing shift time and halving the wear on each. Weight and complexity finally finished it off, though the 956/962 did win races using it. Then came Tiptronic, offering full adaptive auto changes plus manual override. At first its 'plus or minus' control provoked resistance because you couldn't skip a gear, but as sequential shifts became the racing norm, Tiptronic became the hot product. Now your Audi or VW might well have it. Yet Porsche was beaten to the First sequential system on a road car by machines using motorcycle 'boxes, like the Triking and the Rocket, and by Vector, the 1980s American supercar.
In the early 1990s saloon car racers adopted a mechanical sequential change, aiming to cut the 'down-time' between gears. Thumping the lever repeatedly cycled through the ratios much like a motorcycle 'box, and by using dog clutches instead of syncromesh there was no need to use the clutch. It's a simple, tough system: moving the lever turns a cylinder containing two or three machined circumferential zig-zag grooves. A pin on a rocker-arm follows each groove and operates one set of selector forks at a time to select a gear. A ratchet device allows short lever movements to keep turning the cylinder the same way for a series of single down or upshifts. You can't skip gears, but you can't miss one accidentally either, and lightning-fast full-throttle shifts are easy.
In many race and rally classes this system has now superseded the manual H-gate, patented by Daimler before the First World War; ironically it is actually a reversion to on almost identical mechanism first patented in 1896...
Electronic control instead of hydraulic has sharpened the action of conventional auto-boxes, with input from an array of sensors and a choice of response levels. Adaptive systems even learn your driving style and shift accordingly, and several firms offer aftermarket manual conversions for such electronic 'boxes, giving steering-wheel button-shifting.
But where BMW's new M-Sequential unit differs is that increased electronic sophistication has allowed engineers to drop the epicyclic geartrains and torque converter and return to a straightforward pinion 'box, but with computer-controlled actuators moving the selector forks. With the right software and sensors the shifting can be fully auto; delete that and you have fingertip manual selection. Formula One technology hits the road.