The dual-clutch transmission has undoubtedly changed the way we shift gears, with the Volkswagen Golf Mk4 R32 being one of the very first mass-produced cars to feature two clutches. In fact, dual-clutch transmissions have been around since the mid-1980’s when Porsche used them in a variety of Le Mans racing cars.
Since then, the demand for these futuristic gearboxes have rapidly increased, and numerous supercars released over the past few years use dual-clutch gearboxes, with the Ferrari 458 Italia being a prime example.
However, there are three big down sides to double-clutch transmissions:
1. They are generally significantly heavier than regular transmissions.
2. They do not come cheap if a replacement is needed.
3. They are also very costly to develop and produce.
As a result, some manufactures are refusing to use them, such as Lamborghini with their new ISR gearbox which operates on a similar principle but weighs a lot less. However, even Lamborghini’s latest gearbox may be short lived as there is a new wave of transmissions heading our way, which are promising zero shift times, as well as being cheaper and most importantly lighter.
One British company, Xtrac is currently developing what they hope will be that new wave of high performance transmissions. Xtrac may ring a bell with the motorsport fans out there as they build transmissions for Formula One, WRC, Dakar Rallying, and even Le Mans racers so there is no arguing their expertise in creating lightweight and quick-shifting ‘boxes.
Their latest creation is the Instantaneous Gearshift System, (IGS), which as its name suggests, promises to provide instantaneous gear changes. After reading how this system works over and over, we must admit, we still do not have a grip on exactly how it works, but here is our best attempt to describe it in layman’s terms.
Each gear has been individually mounted onto its very own ratcheting clutch system and this differs from ordinary transmissions where the gearshaft and the actual gears are connected via a synchromesh system. When operating, each gear is engaged in the selector system and also ratchets on the shaft until a number of sprung pawls click the gear into place. As a result of this advanced system, when changing up gears, the gearbox actually keeps the revs at the same level, so if you shift from 4th at 6,000 rpm up to 5th the revs will stay at 6,000 rpm.
However, this has no way of working as you could not accelerate, so a bit of driveline wind-up does the trick and forces the revs back down in less than a few milliseconds. This system is currently being used in motorsport so a bit of refinement is still needed to make it suitable for everyday use.
Tune in for Part II in the coming days to see how another British company, Zeroshift is aiming to knock the dual-clutch transmission out of the park with its brand new vision.