Making the control pressure rod longer will make it shift earlier assuming its misadjusted. Did this car shift fine for years then, last week act up? By 'bigger" do you mean longer? Also I've seen bushings missing on linkages either up top or at the trans affecting shift points. Also put year and type of Mercedes in your signature profile.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.