Understanding Thread Types and Sizes in Brake Line Fittings

 Understanding Thread Types and Sizes in Brake Line Fittings

Brake line fittings play a fundamental role in a vehicle’s overall braking system. Understanding their structure, particularly the types and sizes of threads they employ is vital for professionals working in the automotive aftermarket. When dealing with a brake line fitting assortment, knowing these details can help ensure efficient and high-quality repairs. In this article, we will delve into the different types and sizes of threads used in brake line fittings.

Understanding Brake Line Fittings

Brake line fittings are the small but crucial elements that connect the brake line to the rest of the vehicle’s braking system. They come in various thread types and sizes, each serving a unique function and fitting different vehicle models.

Importance of Thread Types in Brake Line Fittings

Thread types in brake line fittings can differ significantly in terms of their shape, size, and the number of threads per inch. Understanding these specifications can help technicians make informed decisions when selecting the appropriate fittings for brake line repairs. You may also check out this blog post to learn more about brake line repairs. This knowledge can help save time, increase efficiency, and improve the overall quality of work.

Thread Types in Brake Line Fittings: An Overview

There are numerous types of brake line fitting threads. They include:

  1. Unified National Fine (UNF) Threads: Known for their fine pitch, these are commonly used in the automotive industry due to their strength and resistance to loosening.
  2. Unified National Coarse (UNC) Threads: These threads are easier to manufacture and assemble due to their coarser pitch, making them a staple in general industry applications.
  3. Metric Threads: Recognized by the letter “M” followed by a number indicating the thread’s outer diameter, metric threads are widely used in European and Asian automobiles.

Getting to grips with these thread types is essential for brake line fitting assortments in the automotive aftermarket sector.

Understanding Sizes in Brake Line Fittings

When dealing with brake line fitting sizes, it’s crucial to understand that sizes are categorized primarily by the outer diameter of the tube and the thread pitch. The options can range from 3/16 size fittings for smaller vehicles to larger ½ inch fittings for heavy-duty vehicles. Additionally, the thread pitch can range from 24 threads per inch (TPI) to 37 TPI. Having a variety of sizes and pitches in your brake line fitting assortment is crucial for accommodating different vehicle models.


The significance of understanding the different thread types and sizes in brake line fittings can’t be understated. With this knowledge, automotive professionals can confidently select the appropriate brake line fitting assortments for specific repair tasks, thus ensuring the safety, high performance, and longevity of the vehicle’s braking system.

By incorporating these insights into daily practices, car care professionals can achieve the finer details of excellence that contribute to a reputation for quality and efficiency in the automotive aftermarket.

Ian A. Blocker

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