Craig,

Are you suggesting that you would expect the proper old fashioned slushbox to be more reliable than the DSG, or did I read that the wrong way? I'm hoping I didnt :)

Whatever I get I'll def do a ATF change and whatever else to give it the best chance of a long life. I hope 659 pops by here too - he successfully helped me banish some devils from the car I already have a few months back.

I've just added a 1.8T 20v petrol auto to my list..... Don't know if i could do petrol again, however.

Thanks for the very helpful reply

Jim

Edited by brianthnach on 20/06/2011 at 16:20

A good diesel automatic is a difficult engineering problem to crack - hence much development and ingenuity being applied to designs such as the DSG.

The characteristic of the diesel which gives the transmission designer such a hard time is its high torque at low crank speeds. With a conventional torque convertor autobox the high input torque of the diesel has the dual detrimental effect of producing excessive slip = loss = heat and also heavily loads the gears, clutches and bearings.

The torque convertor is the most difficult problem - the other parts can (at a price) simply be made bigger and stronger. Although most transmissions are now provided with a torque convertor lock, this can in practice only be used under steady state conditions with the transmission in a high ratio. Low speed or town running with frequent shifting is extremely lossy and negates most of the diesel's advantages under these conditions.

Enter the DSG and its lookalikes from others. This is an elegant low loss solution to the problem but is not without complexity. It is utterly reliant upon electronics which are usually unfavourably sited within the transmission. Any repair costs are high and the labour involved in the dual clutch replacement is very considerable. If you Google LuK there is actually a procedure for doing this in their published literature - not for the faint hearted.

To the original question: I'm not an autobox expert - very thankfully I'm still able to use a manual but I gather that the torque convertor is indeed the weak point on the B5.5's transmission. Failure tends to occur in the second century of mileage and may be highlighted by the extreme reliability of the old 5 speed manual box. I've hardly ever heard of any problems with these.

The other B5.5 speciality - water ingress - affects the auto models badly because in a further fit of Wolfsburg engineering genius, the transmission controller is on the floor.... This needs to be very carefully watched for if considering the purchase of an auto. I would not buy a car which has ever been wet under the carpets - there are too many connectors, splices and electronic assemblies which eventually end up green and corroded. There's no escaping the laws of physics.

You won't like the fuel consumption of a 1.8T after a PD.

659.