The four-wheel-drive Jaguar XF and XJ unveiled at the Moscow show are not the company’s first foray into all-wheel drive – remember the ill-fated X-type of 1999 to 2007.
But whereas that car was created out of expediency under Ford ownership – to disguise that the X-type was a re-engineered Mondeo – the XF and XJ have been developed for solid marketing reasons.
Making all this happen in two cars which were never designed to accommodate all-wheel drive was not easy. The XF platform is a development of the one which dates back to the S-type (and contemporary American Fords) while the XJ has evolved from the previous model.
‘It’s a relatively straightforward four-wheel-drive system,‘ says chief programme engineer Andy Dobson. Packaging it in the two cars was the difficult part.
The front differential is mounted at the side of sump, which means that the lay shaft connecting the front driveshafts has to run through the sump. This meant raising the engine by 15mm to maintain oil capacity, which in turn enforced changes to the floorpan and subframe. The front suspension knuckles have also had to be split to make room for the driveshafts.
‘The really clever part was to make the cars drive like the rear-wheel-drive models,’ says Dobson. Changes to the suspension geometry and steering arms have helped in achieving this, and the springs and anti-roll bars have been changed to take into account that four-wheel-drive adds 110kg to all-up weight.
The four-wheel-drive system diverts all engine torque to the rear when the car is being driven normally on dry
roads, but can send as much as 98 per cent to the front in extreme slippery conditions. It takes into account the slip angles in the wheels, the throttle position and the steering angle.
Ten per cent of torque goes to the front when setting off to aid traction, but this increases to 30 per cent when the eight-speed automatic transmission is in its ‘Winter’ setting.
‘We had to be nimble because the American market is moving increasingly towards four-wheel drive, especially in the snowbound states,’ says Dobson.
‘It was completed in only 18 months. We used some things from the X-type as a starting point and we obviously have a lot of experience within Land Rover, but this is an all-new Jaguar four-wheel-drive project.’
Featuring a New All-Wheel Drive System and New Powertrains
US Models and MSRP(1):
XJ: $73,200 3-liter supercharged V6, 340hp
XJ AWD: $76,700 3-liter supercharged V6, 340hp
XJL Portfolio: $81,200 5-liter naturally-aspirated V8, 385hp
XJL Portfolio AWD: $83,700 3-liter supercharged V6, 340hp
XJ Supercharged: $89,600 5-liter supercharged V8, 470hp
XJL Supercharged: $92,600 5-liter supercharged V8, 470hp
XJ Supersport: $112,600 5-liter supercharged V8, 510hp
XJL Supersport: $119,100 5-liter supercharged V8, 510hp
XJL Ultimate: $155,000 5-liter supercharged V8, 510hp
Source: Headline Auto
by Mircea Serafim
) - Friday, August 31st, 2012 - filed under Editors
. Image credit: Jaguar.