The most precise replacement for "some brake things" in a domain-specific language would be "things that stop the car." This phrase clearly indicates components involved in the braking system. However, if you're looking for a more technical term, "some parts that wore out" could also fit, as it suggests specific components that have failed over time.
If you want specific parts relevant to braking, "the wheel cylinders" would also be appropriate if those are indeed the components in question.
However, since you're looking for the most suitable replacement in a general manner, I would recommend "things that stop the car."