Is this normal?? 1981 300D transmission question

[moorerp]

Hi there,

I just bought a 1981 300D for conversion to alternative fuel, and the car is really great except (possibly) for one thing; in all gears it has flaring and hard shifting issues that I can pretty much alleviate completely just by completely removing my foot from the accelerator at the proper moment for shifting. In other words, I can make the transmission shift whenever I want to simply by removing my foot from the gas pedal. Is this the way it's supposed to work, or am I experiencing some of the famous Mercedes shifting problems?

thanks in advance for any advice,
randy

[blueranger]

the shifting quality is controlled by vacuum... and it sound like
a bad vac modulator control which sits on the fuel pump...

[C32AMG]

You have a control problem; vacuum not being controlled, and or an out of adjustment Bowden cable / throttle control pressure.

[blueranger]

remove the vac hose to the trans.... it will probably start shifting through all
4 gears....

then you will need to replace the vac control on the fuel pump or the vac mod inside the tranny.

[moorerp]

thanks for the responses, guys. I forgot to mention that the cruise control slowly drops in speed when it's engaged and the door locks function properly but very slowly. Could a vacuum leak somewhere other than the modulator be causing the shifting problem?