Changing space before chapter without titlesec package

Question

I am sorry if this is a repeated question, I could not find anything similar on the forum search.

How to adjust the space before the chapter heading without using titlesec package.

I tried this code but no luck:

\renewcommand*{\chapterheadstartvskip}{\vspace*{-\topskip}}

It says that \chapterheadstartvskip is not defined.

Answer 1

You didn't give the documentclass you are using. So I will let loose my guess that it is book. Here the default space above is defined by \vspace*{50\p@}. This can be patched as in this code:

\documentclass{book}
\usepackage{blindtext,showframe}   %% just for demo
\usepackage{xpatch}
\makeatletter
\xpatchcmd{\@makechapterhead}{\vspace*{50\p@}}{\vspace*{20\p@}}{}{}
\xpatchcmd{\@makeschapterhead}{\vspace*{50\p@}}{\vspace*{20\p@}}{}{}
\makeatother
\begin{document}
  \tableofcontents
  \Blinddocument
\end{document}

Adjust 20 in \vspace*{20\p@} as you wish.

Answer 2

I managed to find the answer. The class i am using is \documentclass{abntex2} which is based on the \documentclass{memoir} class

the fix for the chapter space was to combine the metric \beforechapskip with the redefinition of the command \chapterheadstart that somehow got lost inside the abntex2 package.

\renewcommand{\chapterheadstart}{\vspace*{\beforechapskip}}
\setlength\beforechapskip{20mm}
\setlength\afterchapskip{20mm}