I have noticed that the 1-2 and 2-3 shifts on my 95 S320 are somewhat harsh - not quite a "thunk", but harsher than I would expect from this car. 3-4 and 4-5 shifts are quite smooth. Datasheet says that the transmission is a 722508 04 000633.

I've noted that the "harshness" is much more noticable under light load, and in fact on a spirited accelleration, the shifts seem quite smooth and quick.

The dealer said that it shifts "about right for a car of this mileage". Car just ticked over 179,000 km (about 111 000 miles) and I have a hard time believing that this is normal. Dealer did a transmission service (fluid, etc) last fall, with no noticable changes.

I know nothing about automatic transmissions, and am also unlikely to ask the dealer to dig deeper - as they have not demonstrated much transmission knowledge. I've done a fair amount of searching the archives, but am frankly at somewhat of a loss.

Any thoughts?

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Dave

1995 S320

This is a vacuum controlled transmission. There is a device on the side of the transmission called the vacuum modulator that can be adjusted to control the firmness of shifting.

It shouldn't be done arbitrarily but by someone who knows what they are doing. If you go too far, the transmission will flare (slip) when shifting.

The problem could also be a vacuum leak.

Find a dealer who knows what they are doing and have it checked.

What does the vacuum modulator look like?

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Dave

1995 S320

These links take you to Info about transmissions on diesels but you'll see pictures of the vacuum modulator and related information.

http://www.continentalimports.com/ser_ic20242.html

http://www.mercedesdismantlers.com/722.3and722.416_transmission_adjustments#722.3%20Series%20and%20722.416%20Transmission%20Adjustments

You can also search the forum for *vacuum modulator* for more Info.