My 81 had NO bowden cable. The black box controlled 2 things. EGR vacuum signal depending on throttle angle and metered vacuum to the transmission. So, by removing all of this, you now have no adjustable vacuum to the vacuum modulator, so it shifts too early. On my 81 I simply disconnected the source hose from the black box to the EGR temp sender on the thermostat housing. I left everything else intact. The bypassing of the black box only works on auto trans' with a bowden cable.

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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.