Description
Brass Brake Blanking Plug M12 x 1mm Male Undrilled
Solid brass male blanking plug with an M12 x 1mm external thread and no pipe hole (undrilled). Screws into an M12 x 1 female port to seal it – spare master cylinder outlets, valves, and gauge sender ports. Supplied by EMS Spares, Leicester – over 30 years in automotive components.
Specification
| Thread | M12 x 1mm male (1mm pitch) |
|---|---|
| Type | Male blanking plug, undrilled (solid) |
| Hex / spanner size | 12.7mm A/F approx |
| Overall length | 22.3mm approx |
| Material / finish | Solid brass, natural finish – rust resistant, will not seize |
| Interchange reference | HU9B* |
| EMS part number | EMS-A9B |
* 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 blanking plugs and caps explained
What does a blanking plug do?
A blanking plug or cap seals a brake or clutch port, pipe end or hose that is not in use – for example a spare outlet on a master cylinder or T-piece, a removed pipe while you work, or a system being stored. It seals by seating against the flare seat of the port, in the same way a union clamps a pipe flare, so the thread must match exactly.
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. Check the pitch with a thread gauge.
Step 2 – plug or cap?
- Male blanking plug (this part): screws into an M12 x 1 female port.
- Female blanking cap: screws onto an M12 x 1 male port or hose end – see our EMS-A15AB.
How to fit – good practice
- Clean the port and check the seat is free of dirt.
- Start the plug by hand for several turns – it should turn freely.
- Tighten with a 1/2″ (12.7mm) spanner until it seats firmly.
- Check 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 plugs. 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
Is M12 x 1 the same as 1/2″ UNF? No. They look similar but the threads are different and will bind.
Why brass? Brass does not rust or seize, so the blank can be removed again later.
Can I use it on a gauge sender port? Yes, where the port is M12 x 1mm.
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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