On the 722.3, the vacuum modulator does not control the shift point....only softness of the shift (not always the case with other transmissions such as the 722.1). The shift point is only adjusted by the bowden cable.

Check you kickdown switch under the accelerator pedal! If it is stuck in the on position, your car will shift very late. Sometimes the carpet or floor mat will cause it to get stuck.

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All the best,

J. P. Mose
1968 250SL
1970 280SE 3.5 Cabrio
1987 560SL
1990 560SEL