volkswagen

full-time all wheel drive with manually lockable differentials, same as quattro evolution I. See quattro evolutions.

Figure: volkswagen passat b2 transmission layout (142KB)

Figure: volkswagen passat b2 interior diff lock (350KB)

Figure: volkswagen passat b2 front differential (84KB)

Figure: volkswagen passat b2 front drive shaft (89KB)

Figure: volkswagen passat b2 central differential (93KB)

Figure: volkswagen passat b2 propeller shaft (67KB)

Figure: volkswagen passat b2 rear differential (83KB)

Figure: volkswagen passat b2 rear differential lock (108KB)

Figure: volkswagen passat b2 rear differential vacuum lock system (126KB)

Figure: volkswagen passat b2 rear drive shaft (77KB)

Figure: volkswagen passat b2 gearbox (57KB)

viscous coupling automatic all wheel drive system.

A viscous coupling installed instead of a center differential, with freewheel mechanism to disconnect the driven axle when braking. Open rear differential. Open front differential.

In normal conditions, this is a front wheel drive vehicle. In normal driving conditions 95% of torque transferred to front axle. Because viscous coupling is considered to be "slow" (some time is needed for silicone fluid to warm-up and solidify), 5% of torque is transferred to rear axle at all times to "pre-tension" the viscous coupling and reduce activation time. The coupling locks when slipping occurs and up to near 100% of torque is automatically transferred to rear axle. In on-road conditions the car will not move if one front wheel and one rear wheel lose traction.

The freewheel segment, installed inside the rear differential, lets rear wheels rotate faster than front wheels without locking the viscous coupling and preventing ABS from applying brakes to each wheel independently. Because of the freewheel, torque can be transferred to rear axle only when vehicle is moving forward. For all wheel drive to work when reversing, a vacuum-actuated "throttle control element" is installed on the differential case. This device locks the freewheel mechanism when in reverse gear. The freewheel mechanism unlocks when the gear shift lever is pushed to the right pass the 3rd gear. The freewheel is not unlocked immideately after leaving reverse gear on purpose - this is to prevent the freewheel from cycling from locked to unlocked if the car is stuck and driver is trying to rock the car by changing from 1st to reverse and back.

Disadvantages of this all wheel drive system are related to actuation time of the viscous coupling. 1: When cornering under acceleration on a slippery surface, rear axle is engaged with delay causing sudden change in the car's behaviour (from understeer to oversteer). 2: When starting on a sandy surface, front wheels can dig into the sand before all wheel drive is engaged.

Figure: Volkswagen Golf MkII Syncro (87KB)

Figure: Volkswagen Golf MkII Syncro power transfer to the rear axle (99KB)

Figure: Volkswagen Golf MkII Syncro rear axle gear unit with visco-clutch, free-wheel unit, and bevel gear differential. (119KB)

Figure: volkswagen golf 2 syncro (94KB)

Figure: Volkswagen Golf Mk2 Syncro freewheeling mechanism(12) (21KB)

Figure: Volkswagen Golf Mk2 Syncro throttle control element(15) (14KB)

Figure: volkswagen golf 2 syncro (450KB)

Torsen-based full-time all wheel drive. See quattro evolutions.

Figure: vw passat b5 (613KB)

Haldex Generation II automatic all wheel drive. Haldex Generation IV automatic all wheel drive since 2007.

Figure: volkswagen passat 4motion (49KB)

Figure: volkswagen passat 4motion haldex generation 4 (176KB)

Haldex Generation I automatic all wheel drive. Haldex Generation II automatic all wheel drive since 2002. Haldex Generation IV automatic all wheel drive since 2007.

Figure: Volkswagen Golf IV 4motion (109KB)

Figure: Volkswagen Golf IV 4motion (197KB)

Figure: Volkswagen Golf IV 4motion (180KB)

Figure: Volkswagen Golf IV 4motion (182KB)

Figure: Volkswagen Golf IV 4motion (179KB)

Figure: Volkswagen Golf IV 4motion (200KB)

Figure: Volkswagen Golf V 4motion (193KB)

Figure: Volkswagen Golf V 4motion (115KB)

Figure: Volkswagen Golf VI 4motion (69KB)

Haldex Generation V automatic all wheel drive.

Figure: Volkswagen Golf VII 4motion (41KB)

Figure: Volkswagen Golf VII R 4motion (112KB)

Haldex Generation IV automatic all wheel drive.

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Rear wheel drive-based automatic all wheel drive system with torque transfer to the front axle via viscous coupling. Freewheel mechanism(?). Manually locking rear and front differential.

Figure: volkswagen t3 syncro (164KB)

Figure: volkswagen t3 syncro front differential (103KB)

Figure: volkswagen t3 syncro front drive shaft (73KB)

Figure: volkswagen t3 syncro propeller shaft (32KB)

Figure: volkswagen t3 syncro viscous coupling (47KB)

Figure: volkswagen t3 syncro transmission (151KB)

Figure: volkswagen t3 syncro rear differential (95KB)

Figure: volkswagen t3 syncro rear drive shaft (79KB)

Figure: volkswagen t3 syncro transmission (151KB)

Automatic all wheel drive system with torque transfer to the rear axle via viscous coupling. Freewheel mechanism. Optional manually locking rear differential.

Figure: volkswagen t4 syncro (78KB)

Figure: Volkswagen T4 Syncro propeller shaft (69KB)

Figure: Volkswagen T4 Syncro throttle control element in the rear differential (30KB)

Figure: Volkswagen T4 Syncro viscous coupling (25KB)

Haldex automatic all wheel drive. Optional manually locking rear differential.

Full-time all wheel drive. 50/50 torque split under normal conditions. Multiplate clutch lockable center differential. Optional rear lockable differential. Front open differential. Low gear. Differential locks are engaged by ECU, but also can be engaged manually by the driver. The car is also equipped with Hill Descent Control, Hill Start Assist.

Figure: volkswagen touareg 4motion (35KB)

Part-time all wheel drive. Manually lockable rear differential. Manually lockable front differential.

There is a small lever on the floor between the driver's and passenger's seat located next to the passenger's seat that shifts between 4wd and 2wd. This switching is purely mechanical. When you put the Iltis into 2wd it goes into rear-wheel-drive. Engaging the 4wd lever will engage the front wheels.

Between the driver's and passenger's seat located next to the driver's seat is another small lever which switches the differential lock in and out. The diff lock is on the rear wheels. This switching is purely mechanical. Diff lock is normally left in the out position.

The super low first, which is labelled "G" on the shifter, is only available 4wd.

Source: http://magma.ca/~smaclennan/m38a1/iltis.html

Figure: volkswagen iltis (123KB)

Figure: volkswagen iltis (51KB)

Figure: volkswagen iltis 4x4 interior diagram (99KB)

Figure: volkswagen iltis 4x4 transmission (197KB)

Figure: volkswagen iltis 4x4 (466KB)