Description

Brass Brake Pipe Union 3/8″ BSF x 20 Male for 3/16″ Pipe

Solid brass male brake pipe union with a 3/8″ x 20 BSF thread, for 3/16″ (4.75mm) brake and clutch pipe. The older British thread found on Morris Minor, early MG, Austin and other classics, mostly pre-1960s. Supplied by EMS Spares, Leicester – over 30 years in automotive components.

Specification

* Reference numbers are for identification and cross-reference only. EMS Spares is an independent UK supplier and has no connection with the owners of these part numbers. All dimensions are approximate.

Buyer’s guide: brake pipe unions explained

Why brass?

Brass does not rust or seize, so the fitting can be undone again years later without twisting the pipe. It is the traditional choice for classic car brake and clutch lines.

What does a brake pipe union do?

A brake pipe union is the threaded nut that holds a flared brake pipe tight against a component or hose. The union itself does not seal; it clamps the flare on the end of the pipe against the seat of the mating part, and that metal-to-metal contact makes the seal. That is why the thread and the flare type must both match.

Step 1 – identify your thread (the most common mistake)

Tip: 3/8″ BSF and 3/8″ UNF have the same diameter but different threads (20 against 24 per inch) and will not fit each other. Count the threads over one inch or use a thread gauge. Never force a fitting.

Step 2 – male or female?

• Male union: screws into a female port (this part)
• Female union: screws onto a male port or hose – see our EMS-A3A brass BSF female union.

Step 3 – pipe size and material

For 3/16″ (4.75mm) outside-diameter pipe, the standard UK car brake pipe size. Suits copper-nickel (Kunifer), copper and steel brake pipe.

How to fit – good practice

1. Slide the union onto the pipe the right way round before you make the flare.
2. Make the flare with a proper flaring tool, matching the flare of your old pipe and the port it connects to.
3. Start the union by hand for several turns – it should turn freely. If it binds, stop and check the thread.
4. Tighten with a suitable split / flare nut spanner, not an open-ended spanner. Do not over-tighten into soft brass seats.
5. Bleed the brakes, then check every joint for leaks with the pedal pressed hard.

Safety: brakes are a safety-critical system. If you are not confident, have the work done or checked by a qualified mechanic.

Pack sizes

Available as 1, 3, 5, 10 or 20 unions. Larger packs cost less per piece.

Delivery

Free UK delivery on every order (including Northern Ireland, Highlands & Islands). Same-day dispatch on orders placed before 10am.

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FAQ

Will this fit copper (Kunifer) pipe? Yes – any pipe of the stated size: copper-nickel, copper or steel.

Is 3/8″ BSF the same as 3/8″ UNF? No – same diameter, but BSF has 20 threads per inch and UNF 24. For UNF see EMS-A1.

Which cars use BSF? Mostly older British cars, often pre-1960s, such as the Morris Minor and early MG and Austin models. Always check your old fitting.

Need help? Message us with your vehicle and the part you are connecting to and we will confirm the right fitting before you order.