tial is activated, the driver sees agreen light flash on the

instrument panel. Automatic lock-up can be initiated

with wheel slip differences as low as haif a mile per hour,

but the threshold values at which lock-up occurs are var-

iable. At higher speeds, the system permits larger dif-

ferences than at low ones. Since other influences such

as different tire diameters or variations in air pressure

can lead to differences in wheel revolution without slip

being present, “teachable” modules are used which rec-

ognize such factors and take them into account.

Finally, there is a switch on the console by which the

driver can activate the longitudinal and transverse dif-

ferential locks. This full traction program is really in-

tended for stump pulling and stuck-in-the-mud starts

and can be released manually. If the driver forgets, the

control unit automatically switches the traction pro-

gram off at speeds of over 25 mph or whenever ABS is

required.

A track correcting rear axle and no torsion bars

To accommodate the four-wheel-drive system and

ABS brakes, new front and rear axles were designed.

The rear axle deletes torsion bars in favor of coilover

spring and shock units with inner semi-trailing arms

whichhaveatrack correcting effect when strong lateral

forces are present. The basic function is similar to the

Weissach axle of the 928. The new MacPherson front

axle has altered geometry which provides the negative

scrub radius required by the ABS system. As with the

Extendible rear spoiler, which raises automatically at

50 mph, reduces lift and improves engine cooling via

altered pressure cOnditions around the taiL

JANUARY, 1989