crack onto vs go for

crack onto

verb
  • To flirt with; to approach and speak to (someone), seeking romance, love, sex, etc. 

go for

verb
  • To develop a strong interest in, especially in a sudden manner; to be infatuated with. 

  • To try for, to attempt to reach. 

  • To favor, accept; to have a preference for. 

  • To attack. 

  • To apply equally to. 

  • To undertake (an action); to choose an option. 

  • To suffice to be used for; to serve as. 

  • Used other than figuratively or idiomatically: see go, for. 

How often have the words crack onto and go for occurred in a corpus of books? (source: Google Ngram Viewer )