Q. I’m thinking of buying a new Audi A3 but am being put off by reports in recent years of problems with the Volkswagen DSG/Audi automatic gearboxes. Have such faults been rectified?
CM, Woodbridge, Suffolk
A. VW pioneered the direct-shift gearbox (DSG), which is called S tronic when fitted to vehicles made by its Audi subsidiary. It consists of a manual gearbox with an extra shaft and two mechanical clutches, all operated by a computer and servo motors. The double clutch is the innovation: it speeds up the gearchanges, maximising smoothness and efficiency.
One gear can be engaged with the clutch driving it, with the next gear also engaged but its clutch disengaged, ready to go when the computer swaps from one clutch to the other. It reduces the time taken to change up a gear to about one-hundredth of a second.
There have been a few well-publicised problems relating to the double clutch on VW’s six and seven-speed DSG transmissions. The double clutch on the six-speed version has always been a “wet” one, where the clutch is cooled by having gear oil pumped through it, but the seven-speed version was launched with a more normal dry clutch. Unfortunately, this was prone to overheating and seizing up, so in 2008 Audi introduced a seven-speed wet clutch that seemed to end these problems.
But then both six and seven-speed models began to develop problems with the wet clutch. In some hot and humid climates the oil could start to vaporise, causing electrical problems under stop-start urban driving conditions. VW changed the type of oil used from a synthetic to a mineral one, which cured the problem.
Since then there appear to have been far fewer problems with this new transmission technology and other car makers are introducing their own versions.
Q. I want to buy a 2008 Volkswagen Cross Golf but have heard of problems with the DSG transmission. The seller’s warranty excludes “failure of the mechatronic valve body”. Should I proceed?
A. The Golf you’re looking at almost certainly has the seven-speed dry clutch; VW issued a recall of that box to fix a problem that could cause a malfunction in the mechatronic unit, which controls the gearshifts. You should ask the seller for evidence that the recall work has been done.
If the unit fails, firms such as BBA Reman (bba-reman.com/uk) can fix it for about £250, plus labour.
TIM’LL FIX IT
Tim Shallcross used to train AA patrols to fix cars. Now he advises the Institute of Advanced Motoring — read more from Tim here.
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