Description
Brass Brake Pipe Union M12 x 1mm Male for 3/16″ Pipe
Solid brass male brake pipe union (male tube nut) with an M12 x 1mm external thread, made for 3/16″ (4.75mm) brake and clutch pipe. Screws into M12 x 1 female ports – many master cylinders, pressure valves and larger calipers. Supplied by EMS Spares, Leicester – over 30 years in automotive components.
Specification
| Thread | M12 x 1mm male (1mm pitch) |
|---|---|
| Pipe size | 3/16″ (4.75mm) brake / clutch pipe |
| Type | Male union (male tube nut) |
| Hex / spanner size | 12.7mm A/F approx (1/2″ split / flare nut spanner) |
| Overall length | 22.3mm approx |
| Flare type | N/A |
| Material / finish | Solid brass, natural finish – rust resistant, will not seize |
| Interchange reference | HU9* |
| EMS part number | EMS-A9 |
* 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
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)
| Thread | Outside diameter (male part) | Threads | Typically found on |
|---|---|---|---|
| M10 x 1mm | 10mm approx | 1mm pitch (about 25 per inch) | Most European and Japanese cars, many later British cars and kit cars |
| M10 x 1.25mm | 10mm approx | 1.25mm pitch | Some older Italian and French cars (e.g. Fiat, Lancia) |
| 3/8″ x 24 UNF | 9.5mm approx | 24 per inch | Most British classics: MG, Triumph, Mini, Land Rover Series |
| M12 x 1mm (this part) | 12mm approx | 1mm pitch | Larger ports, some master cylinders and 1/4″ pipe |
Tip: M12 x 1 is the larger metric brake thread (12mm across the male thread) – do not confuse it with M12 x 1.25 or 1/2″ x 20 UNF, which look similar. Measure the male thread and check the pitch with a thread gauge. Never force a fitting.
Step 2 – male or female?
- Male union (this part): thread on the outside – screws into a threaded hole (master cylinder, wheel cylinder, caliper, T-piece, brake valve).
- Female union: thread on the inside – screws onto a male port, such as the end of many flexible brake hoses. For a 1/4″ pipe in the same thread see our EMS-A15.
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. Match the flare on your pipe to the port it screws into – most metric ports take a DIN (inverted) or ISO bubble flare; if in doubt, copy the flare on your old pipe.
How to fit – good practice
- Slide the union onto the pipe the right way round before you make the flare.
- Make the flare with a proper flaring tool, matching the flare of your old pipe and the port it screws into.
- Start the union by hand for several turns – it should turn freely. If it binds, stop and check the thread.
- Tighten with a 12.7mm (1/2″) split / flare nut spanner, not an open-ended spanner, so the brass hex is not rounded.
- 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, 2 or 3 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 3/16″ (4.75mm) brake pipe: copper-nickel, copper or steel.
3/16″ or 1/4″ pipe? This union is for 3/16″ pipe. For 1/4″ pipe in M12 x 1 see EMS-A15.
Which spanner do I need? The hex is 12.7mm A/F – a 1/2″ split (flare nut) spanner fits best.
Need help? Message us with your vehicle and the part you are connecting to and we will confirm the right fitting before you order.
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