Clutch Master Cylinders, Adapters & Slave Cylinders — Defender Guide

Pioneer 4x4Technical Reference
Clutch Masters, Adapters & Slaves

Which clutch line fits your Defender is decided by your master cylinder adapter and your gearbox – not by your engine. This guide sets out every thread size across the range so you can order once and fit once.

This is the single most common question we're asked, and the source of most wrongly-ordered clutch lines. Owners work from the engine – “I've got a 300Tdi, so I need the 300Tdi line” – and that assumption is only half right.

In reality the clutch hydraulic circuit has two independent ends, and each is decided by something different:

Master end

Decided by the adapter

Every Defender clutch master cylinder has the same 3/8″ UNF outlet port. The port itself never changes across the range.

What changes is the adapter screwed into it. That adapter sets the thread your line actually connects to.

Slave end

Decided by the gearbox

The slave cylinder thread follows the gearbox, not the engine.

An LT77 and an R380 take different threads – so two 200Tdi vehicles can need two different lines depending on what box is behind the engine.

Check the adapter and check the gearbox. Never order on engine model alone.
Master cylinder side

Port and adapter threads

Vehicle Master port Adapter – line side
Defender 200Tdi 3/8″ UNF 7/16″ UNF
Defender 300Tdi 3/8″ UNF 7/16″ UNF
Defender Td5 (with T switch) 3/8″ UNF M12 × 1.0
Defender Puma / Tdci (with T switch) 3/8″ UNF M12 × 1.0

The master cylinder casting itself is common across the range – part number STC500100 supersedes the earlier STC100, 591226, STC100410 and STC100411. If you have replaced your master and your old line no longer fits, the master is almost never the problem. Check the adapter.

Slave cylinder side

Slave threads by gearbox

Gearbox / setup Typical engine Slave connection
LT77 200Tdi 7/16″ UNF
R380 300Tdi → Td5 M12 × 1.0
R380 “stumpy” – original 200Tdi M12 × 1.0
R380 “stumpy” – Ashcroft kit 200Tdi 7/16″ UNF
Puma 2.4 / 2.2 TDCi Puma Push-fit – no thread
The one that catches people out

200Tdi on a stumpy R380. The original stumpy slave is M12 × 1.0. But the Ashcroft conversion kit for a stumpy uses the 200Tdi slave cylinder, which makes that slave 7/16″ UNF instead. Two identical-looking 200Tdi vehicles on stumpy boxes can therefore need two different lines. If you have a stumpy, look at the slave itself before you order – don't assume from the gearbox alone.

Before you order

Three things to check

  • Which adapter is fitted to your master cylinder – 7/16″ UNF or M12 × 1.0 on the line side
  • Which gearbox you have, and on a stumpy, which slave cylinder is actually on it
  • Whether your vehicle is RHD or LHD – the master-to-bulkhead lines differ in length and routing

If you're unsure whether your fitting is male or female, see our male & female fitting explanation.

Which line do I need

Defender clutch lines by model

Model Master → bulkhead Flexi One-piece master → slave
200Tdi 1990–1994 NRC8330 RHD
NRC8329 LHD 		RTC4425 RHD
LHD
300Tdi 1994–1998 ANR2162 RHD
ANR2945 LHD 		NTC9055 RHD
LHD
Td5 1998–2007 STG101100 RHD
STG500190 LHD 		NRC2211 RHD
LHD
V8 1998–2007 – NRC2211 –
Tdci 2007–2016 STG101100 RHD STH500060 –

On Tdci (Puma) models the master cylinder runs an M12 × 1.0 adapter, and the flexi terminates in a push-fit connection at the slave – there is no threaded slave union to match. The STG101100 line covers master to bulkhead, and the STH500060 flexi runs bulkhead to the push-fit slave.

Fitting

Once you have the right line, routing, slack, torque and bleeding all matter. Everything you need is in our brake & clutch line fitting guide.

Still not sure?

Send us a photo

If you're unsure which adapter or slave you have, take a photo of the fitting and send it to us on WhatsApp. We'd far rather spend two minutes identifying it than have you fit the wrong line.

Email pioneer4x4@outlook.com · Tel 01404 643149 · www.pioneer4x4.com