TRANSFER BOX TYPES

THERE HAVE been several incarnations of the LT230 transfer box since it was first introduced on the pre-defender One Ten model to provide permanent four-wheel drive via its centre differential. All versions share the same basic design and external dimensions, and they also share a similar low ratio (3.2:1 on Discovery for instance). The high ratio gears vary according to the vehicle model, with Defenders generally having a lower ratio than Discovery models. Typically, an early Defender would have a high ratio of 1.41:1 and a Discovery would have 1.21:1, though there are exceptions. Remember, the lower the ratio number, the higher the gearing.

LT230R was fitted to a few early utility models and has the lowest high ratio of all, at 1.667:1 (same ratio as the LT95 combined gearbox/transfer box fitted to early V8 utility and Range Rover models)

LT230T is the most common variant, fitted to 5-speed and some auto Range Rovers up to 1989, Ninety, One Ten, and Defender (except 4-speed V8s), and Discovery 1. Post 1989 Range Rovers had chain-driven Borg Warner transfer boxes.

LT230Q was fitted to Td5 Defenders onward, and is slightly quieter in operation (hence the Q) thanks to different gear geometry, more teeth on the gears, and

improved bearings.

LT230SE the SE version was fitted to Discovery 2. It is similar to the LT230Q and has the same gearing ratios, though the torque handling capacity is higher. There are subtle internal changes such as a selectable spacer (replacing the collapsible type) for setting the intermediate gear bearing preload. The front output flange and mud shield is improved, and Discovery 2 model-specific changes include absence of speedo drive gears (D2 uses an electronic sensor), and the diff lock lever was removed and/or the diff lock mechanism itself, depending on production date.

Earlier boxes As mentioned, the LT230 gear principle is derived from earlier transfer boxes fitted to Series models, which mostly had permanent rear-wheel drive only, with manually selectable front drive (all Series vehicles are in permanent four-wheel drive when low ratio is selected). But permanent four-wheel drive appeared first on the Series I between 1950 and 1954, though that was achieved using a freewheel device on the drive to the front axle. Permanent four-wheel drive reappeared in the Series III Stage One V8 model (1979-85) using the same LT95 combined four-speed gearbox and transfer box unit as the early Range Rover, with its vacuum operated centre diff-lock.

Identifying the transfer box When buying components or considering a ratio change we need to know which LT230 transfer box is fitted, but transfer boxes tend to get swapped around as used boxes replace worn units, or vehicles are re-geared. The ratio of the transfer box may be shown on a label attached to the rear of the casing, otherwise you will be able to find the serial number on the lower rear face or on the rear bottom of the left side (below the PTO cover). But even this may not necessarily confirm the ratio, because the gear set may have been changed in the past. The serial number is found on the lower rear corner below the PTO cover, or just round to the left side.