Suppressing em-dashs for recurrent authors and letter suffixes for years when using biblatex-chicago

biblatex-chicago unfortunately doesn't have a dashed option like the standard styles. To avoid printing the dash, you can clear \bbx@lasthash before printing each entry using the \AtEveryBibitem hook. \bbx@lasthash normally expands to the name hash of the last entry. It is used by the drivers for dash checks.

The alphabetic year suffix used for disambiguation corresponds to the extrayear field. It can be cleared with \AtEveryBibitem as well.

Just add the following to your preamble:

\makeatletter
\AtEveryBibitem{%
  \global\undef\bbx@lasthash%
  \clearfield{extrayear}}
\makeatother

To remove the letter suffix after the year, add the following to your preamble:

\DeclareFieldFormat{extradate}{}