The MG ZR, ZS and ZT manual gearbox line-up changes by car, engine and (on the ZR and ZS) by production date. The early R65 cable-shift five-speed (a PSA-derived unit licensed to Rover) was fitted to the smaller K-series ZR 105 (1.4) and ZS 110 (1.6) from launch in summer 2001, and was replaced by the Ford-derived Getrag-built IB5 from mid-2003 (change-point VIN 3D 720773) on cost and availability grounds. The PG1 five-speed (Rover's own well-regarded unit) was fitted to all 1.8-litre K-series cars (ZR 120, ZR 160 VVC, ZS 120, ZT 120 and ZT 160 K-turbo), the KV6 ZS 180 and ZT 160/180/190, and the L-series TD models. The MG ZT used the Getrag 283 five-speed manual, with sporting lower ratios on the ZT 190.
The ZT 260 V8 used the Tremec TR-3650, the only non-Ford OEM application of that gearbox. A ZR 105 from 2002 carries a different gearbox to a ZR 105 from late 2003, and the difference matters for clutch kits, master and slave cylinders, driveshafts and gear linkages.
R65, IB5 and PG1 in ZR, ZS and Diesel TD
The R65 cable-shift five-speed is the original gearbox of the ZR 105 and ZS 110 from 2001 to mid-2003. Clutch kits for the R65 are sized to the smaller K-series engines, with the slave cylinder mounted externally on the bellhousing, a substantially easier clutch service than the later units. The IB5 that replaced the R65 from VIN 3D 720773 is the same gearbox family fitted to contemporary Ford Fiesta and Focus models, also cable-shift, with a sealed-for-life oil fill (Castrol BOT130M) intended to last 105,000 miles or seven years. The PG1 used on all 1.8-litre K-series, KV6 and L-series TD cars is the strongest of the FWD gearboxes, with a separate filler and drain plug arrangement and a specific MTF94 gearbox oil, using a generic multigrade can cause notchy synchromesh.
Clutch kits for the PG1 are matched to engine and torque output, and the clutch flywheels differ between non-VVC, VVC and diesel applications.
Getrag 283 in MG ZT and the Concentric Slave
The Getrag 283 fitted to all manual ZT and ZT-T petrol and diesel models is supplied from Getrag Ford Transmissions' Bari, Italy plant, a different gearbox from the FWD PG1. It has a longer torque rating (suitable for the 2.5 KV6 in 190 PS Plus form and the M47R diesel's 300 Nm), and uses MTF94 oil with around 2.2 litres for a fill from empty. The single most important service consideration is the concentric clutch slave cylinder, mounted inside the bellhousing on the input shaft. A failed concentric slave cannot be reliably accessed without removing the gearbox, so a clutch replacement should always include the concentric slave. ZT KV6 cars in 190 'Plus' specification used a closer-ratio version; lower-power ZTs used the standard ratio.
Dual-mass flywheels are fitted to the higher-torque KV6 and CDTi applications and should be inspected during clutch replacement rather than reused on principle.
Tremec TR-3650 and Hydratrak in the ZT 260 V8
The ZT 260 uses a fundamentally different drivetrain. The Tremec TR-3650 five-speed manual is the same gearbox fitted to the 2004 Mustang GT, mounted longitudinally behind the 4.6 V8 and feeding a Dana Hydratrak limited-slip differential via a two-piece propeller shaft. The TR-3650 is filled with automatic transmission fluid (the original Mustang application specifies ATF rather than gear oil), and the Hydratrak takes a specific friction-modified limited-slip oil that must not be substituted with a standard hypoid oil, the Autocar buyer's guide flags incorrect rear differential oil as a known cause of premature LSD wear. A clutch kit comprises disc, pressure plate, release bearing and pilot bearing matched to the Modular V8, with a dual-mass flywheel fitted as standard. Tremec gearboxes and Hydratrak differentials are unique to the ZT 260, with approximately 717 cars built (of an 883-car combined V8 total), so parts are intrinsically rarer than FWD ZT components.
Automatic Transmissions: JATCO JF506E and Ford 4R75W
The 5-speed automatic option on the FWD ZT range is the JATCO JF506E, one of the first transverse-engine deployments of that transmission, introduced in January 2002 with the ZT 180 Auto (KV6) and rolled out across the diesel CDTi and other FWD specifications during the production run. Calibration is mapped to each engine variant (KV6, 1.8 K-turbo and CDTi calibrations are not interchangeable). The JF506E has well-documented age-related issues including reverse-piston wear and solenoid pack failures that cause harsh shifts at lower mileages than buyers expect; both can be addressed in situ, which makes JATCO service kits and solenoid pack replacements important catalogue items.