Republicans used to receive the majority of the Black Vote until Nixon’s Southern Strategy.
That dates the change to 1968, but Kennedy and Johnson won the majority of the black vote, too. I think the change really goes back to FDR.
AFAIK, Ike won a majority of that vote, and Nixon got the last highest Republican vote total at 20 something percent.
That would make my point that since 68, Republicans have bled black voters, not sure about Ronald Reagan though.