2001 May: There are grumblings amongst some four wheel drivers that the Land Rover Discovery Series II, with all its gee whiz electronic traction control and HDC, may be less safe than possible in certain extreme four wheel drive situations.

At least one owner has had the traction control electronics go "out to lunch" while on a steep and rocky climb. This left the car with three open differentials, and traction equal to only 4× the minimum available to any one wheel. The reason is that the Discovery relies on the traction control system to brake any slipping wheel. No electronics  plus  one wheel in the air = no traction. All it takes is a u/s wheel sensor or a broken wire.

2001 Victorian 4WD Show

Even with the traction control system working, some owners believe that it does not offer the ultimate security of a centre differential lock in certain hard four wheel drive situations, such as reversing down a steep pitch when forward progress is impossible. The irony is that the car is in fact fitted with a centre diff' lock - but there is no way of engaging it from inside the cab the way that the Discovery is sold (it is possible from beneath the vehicle but that is not a nice prospect on a steep hillside or in mud). John Davies Motor Works has a kit, also available at Ritters (search [links]), for ~400 which enables the centre diff' to be locked, in low-range only, as it is thought necessary to have the diff' unlocked at all time in high range so as not to interfere with the ABS brakes.

(The Discovery is configured so that if the diff' lock is engaged, while the engine is not running, the traction control will disable. This means that the vehicle can be operated with traction control, or with centre diff' lock engaged and no traction control or, by engaging diff' lock with the engine running, with both centre diff' lock and traction control. This last option is presumably in contradiction to Land Rover's intent. The diff' lock kit simply eliminates the need to crawl under the car and engage the diff' lock by means of a spanner on the end of the engagement shaft. [-R. S.])

There are rumours that Land Rover experts have been to tests in Australia, and rather wish they had made the Discovery Series II's diff' lock lockable from the cab back in 1998; perhaps this will be a future revision? Contrast the situation with the Land Rover Defender which has essentially the same transmission as the Discovery but with the lockable centre diff' lock; the Defender Xtreme's traction control is differently programmed to be compatible with the diff' lock. And the Range Rover which has a viscous coupling which acts as an automatic centre diff' lock. However, before modifying your Discovery it is essential to contact Land Rover first as any modifications would likely void the warranty.

Land Rover Discovery

• station wagon, 5 seats (+2 option), 4 doors, ABS, twin SRS airbags
• loa: 4630mm, width: 1885mm, height: 1935mm (with roof rails) track: 1540mm/1560mm
• approach: 31°, departure: 21° (25° with rear air susp')
• turning radius: 5.95m
• weight: 2065kg - 2225kg (unladen), GVM: 2750kg - 2880kg, towing: 750kg (unbraked), 3500kg (braked)
• petrol:
  • 4L nominal, petrol, V8, mpfi, 2-valves/cyl, ohv
• diesel:
  • Td5, 2.5L, diesel, 5-cyls, direct injection, turbo-charged, intercooled, 2-valves/cyl, sohc
• transmission: R380 5-speed manual/ ZF ZF4HP22EH 4-speed auto'; LT230Q transfer case, full-time 4WD
• suspension: front live-axle & coils/ rear live-axle Watts-link & coils (base) or air (ES),
  brakes: disc/disc, ABS, ETC, transmission hand-brake
• tyres: std 235 on 16x7J alloy wheels, option 255 on 16x8J alloy wheels, option 255 on 18x8J alloy wheels,
  fuel-tank: 95L
• standard: air conditioning, 4-spkr radio/ cassette, electric windows and mirrors
• competition: GM Holden Jackaroo, Jeep Cherokee, Mitsubishi Pajero, Toyota Prado
• [prices]

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