I bought a 1983 240D that has 127K on it and the automatic transmission shifts very hard at high engine speed into 3 and 4. It shifts easier when I let up on the accelerator. I live in a rural area in North Dakota and the local transmission shop scares me. (They don't have a clue)What can I do to fix this problem?
Sam

How firm the shifts are is controlled by the engine vacuum via some kind of vacuum modulator. There are a number of vacuum "switches" in the system as well.

I recently had a very similar problem on my '83 240D (which has a fairly new transmission), and it turned out to be a lack of vacuum to the transmission caused by a faulty vacuum switch .

By the way, I have first hand experience of 3 different Mercedes transmissions lasting between 180k and 205k miles before requiring replacement. The 205k one was my 240D above, so hopefully your's has a long way to go.

I would strongly advise you find yourself a knowledgeable independent [not the main dealer] Mercedes mechanic and get the car properly serviced on a regular basis. Over the long haul it could save you a lot of time and money.
regards
dominic godfrey
Morgan Hill, California

Are you interested in adjusting it yourself? Do you have a vacuum gauge?

If not, I agree with the above comments about finding a pro. One who has been working on MB since your car was made would be nice. The vacuum system used on your car was unique to 80-83 240Ds and 80-81 300Ds. It was mostly unique in that it doesn't have a control pressure link. Adjusting the system is almost an art. A tranny shop wouldn't be likely to know a thing about the vacuum system let alone how to finesse it.