This is a sentence from John le Carre's novel 'The Honourable Schoolboy'.

>"Luke drove as if they were in a jeep, in high gear with ***hammer changes*** on the corners."

Does anyone know what 'hammer changes' mean?

We looked up "hammer changes gear shift Jeep" and got [this;][1]


  [1]: https://www.google.com/search?client=firefox-b-d&q=hammer%20changes%20gear%20shift%20Jeep