Description
Steel Brake Pipe Repair Kit 3/8″ UNF Joiner + 2 Male Unions for 3/16″ Pipe
Steel brake pipe repair set for 3/16″ (4.75mm) brake and clutch pipe. Each set has 1 x 3/8″ x 24 UNF double-female inline joiner and 2 x 3/8″ x 24 UNF male unions – everything you need to cut out a damaged or corroded section of pipe and join it in line. Supplied by EMS Spares, Leicester – over 30 years in automotive components.
What’s in the set
- 1 x 3/8″ UNF female-female inline joiner (HU20* type)
- 2 x 3/8″ UNF male unions, long, for 3/16″ pipe (HU1* type)
Need the parts singly? See our 3/8″ UNF male union (EMS-A1) and 3/8″ UNF inline joiner (EMS-A20).
Specification
| In each set | 1 x inline joiner (female-female) + 2 x male unions |
|---|---|
| Thread | 3/8″ x 24 UNF (24 threads per inch) |
| Pipe size | 3/16″ (4.75mm) brake / clutch pipe |
| Male union | Long, with pilot lead – 21mm overall, 17mm thread approx |
| Weight | 8g approx per male union |
| Material / finish | Steel, zinc plated finish |
| Interchange reference | HU1* + HU20* (brass equivalents) |
| EMS part number | EMS-K21S |
* 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: steel brake and fuel pipe unions explained
Why steel?
Steel fittings are strong, hard-wearing and low cost, and match the original-equipment style on many fuel and brake lines. A plated finish helps resist corrosion. For a part that will never seize, see our brass or stainless steel versions.
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 |
|---|---|---|---|
| 3/8″ x 24 UNF | 9.5mm approx | 24 per inch | Most British classics: MG, Triumph, Mini, Land Rover Series, Jaguar, kit cars |
| 3/8″ x 20 BSF | 9.5mm approx | 20 per inch | Older British cars, often pre-1960s (Morris Minor, early MG, Austin) |
| 7/16″ x 20 UNF | 11.1mm approx | 20 per inch | Larger British ports, some master cylinders and 1/4″ pipe |
| 1/2″ x 20 UNF (this part) | 12.7mm approx | 20 per inch | Fuel lines, carburettors and larger brake ports (5/16″ or 1/4″ pipe) |
| M10 x 1mm | 10mm approx | 1mm pitch | Most European and Japanese cars, kit cars |
Tip: 3/8″ UNF and M10 x 1 look almost the same and will start to screw together, then bind. Never force a fitting. Measure the male thread and check the pitch with a thread gauge.
Step 2 – male or female?
- Male union: screws into a female port (this part)
- 5/16″ pipe version – see our EMS-A24S.
Step 3 – pipe size and material
For 1/4″ (6.35mm) outside-diameter pipe – larger brake and clutch lines. Suits copper-nickel (Kunifer), copper and steel 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 connects to.
- Start the union by hand for several turns – it should turn freely. If it binds, stop and check the thread.
- Tighten with a suitable split / flare nut spanner, not an open-ended spanner.
- 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 set (1 joiner + 2 male unions), 3 sets (3 joiners + 6 male unions) or 6 sets (6 joiners + 12 male unions).
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