Tuesday 6th November 2012


S TRONIC SECRETS

More on the R8's new DSG and why even Audi insiders reckoned the old robo-manual R tronic was a weak spot


It's funny how the official line alters on these things once a new variant emerges, but an Audi drivetrain engineer we met on the launch for the facelifted R8 was refreshingly candid about the outgoing R tronic. "You had to learn how to get the best from it, feather the throttle a little on the shifts, otherwise..." he lurches his head forward and back and anybody who has experienced that gearbox will know exactly what he means. "But the S tronic is perfect - you can't get it wrong."

Shorter, heavier but more efficient than R tronic
Shorter, heavier but more efficient than R tronic
The seven-speed S tronic gearbox is described as 'totally new', developed in-house by Audi and only for use in the R8. At less than 60cm in length, it is some 16cm shorter than the R tronic robo-manual it replaces. That allows more mass to be kept between the axles - but there is a weight penalty of 25kg if you opt for this transmission over the manual.

The new box is described as a 'three-shaft layout'. The two clutches are positioned one behind the other and serve two independent sub-transmissions with gears shifted directly as the clutches open and close.

This layout means that you can 'overleap' the intervening gears and go direct from, say, seventh to second without having to shift in sequence.

New drivetrain puts the R8 back in the fight
New drivetrain puts the R8 back in the fight
It's fast, too. Audi says that the time for a complete shift is 0.23 seconds - that breaks down as 0.11s 'reaction' time and 0.12 shift time. It makes it feel as if acceleration is unbroken and if shifting while still under lateral load, the balance of the car is all but unaffected.

The numerical advantages are plain to see elsewhere on the spec sheet, too. With seventh effectively an overdrive gear, there are gains in both economy and emissions: according to Audi, the S tronic is 21g/km cleaner, 1.3mpg more efficient, 0.3 seconds faster from 0-100km/h and 2,410 cheaper as an option - 2,900 versus 5,310 - when compared to the R tronic it replaces. In an arena governed by increasingly diminishing returns, those figures aren't to be sniffed at.

So from a performance perspective, it is the model to go for. It will also be the one to go for from a residuals point of view. Audi predicts that 75 per cent of R8 customers globally will go S tronic with the revised range. Interestingly, in the UK, a market traditionally associated with a strong demand for manuals, that figure is expected to be 82 per cent. A marked change to the existing split: a quick scan on Autotrader reveals 93 manual cars for sale and 53 R tronics ... a ratio broadly repeated in the PistonHeads classifieds.

Mid-corner shifts don't upset balance
Mid-corner shifts don't upset balance
Chatting with an anonymous Audi sales manager it appears the gearbox may even have been a deal breaker in some cases. "There were several prospective purchasers who wouldn't buy a manual but when they tried the R tronic hated it so much it cost the sale," he reveals. "So it was a bit of a compromise: the demand was for auto, but the R tronic wasn't much cop. Now the 'box lives up to customer expectations both initial demand and future residuals will harden for S tronic and push ahead of manual versions."

For some people a double-clutch transmission will never replace the pleasure of pushing pedals and pulling levers as an integral part of the physical process of driving. For those that demand a two-pedal set up, it's good to know that the choice doesn't have to mean a compromise.

Author: Dom Holtham
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