Central epicyclic unit with Ferguson viscous coupling, Torsen rear differential Source
Figure: Alfa-Romeo 155 Q4 (96KB)
Figure: Alfa-Romeo 155 Q4 front differential with epicyclic torque distributor and Ferguson VC (60KB)
Figure: Alfa-Romeo 155 Q4 rear differential (27KB)
Also see Lancia Dedra/Fiat Tempra.
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155 V6 TI (DTM racecar)Next
- Front and rear: ZF plate-type limited slip differential
- Center: epicyclic unit with Ferguson viscous coupling (distribution F/R 33/67)
Figure: 155 V6 TI 1993 (1161KB)
Figure: 155 V6 TI 1995 (962KB)
Figure: 155 V6 TI 1995 (1177KB)
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156 Q4 (2003-2007)Next
Full-time all wheel drive system with centre Torsen C (T3) differential.
AWD system available only with the 1.9 diesel engine JTDm 16v (110kW).
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159, Brera, Spider Q4 (2005-2011)Next
AWD system: "Q4"
Full-time all wheel drive system with centre Torsen C differential ("Torsen T3 Twin diff").
Distribution: 57% rear, 43% front.
Integrated with ASR and VDC (ESP by Alfa Romeo).
Probably the same Q4 version of Alfa Romeo 156 Crosswagon.
AWD system available only with these "Q4" models:
3.2 petrol engine JTS V6 24v 191kW years 2005->2009 Automatic / Manual Transmission
2.4 diesel engine JTDm 20v 154kW years 2007->2009 Automatic / Manual Transmission
ALFA-ROMEO Q4 system
-used on 159, Brera, Crosswagon
-transversely mounted engine
-Torsen C (twin diff?) center diff
-torque front/rear axle: 43/57%
BLUE - engine input
RED - front axle diff output
YELLOW - rear axle output
BLACK - front axle diff with drive shafts
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Asymmetric full-time all wheel drive with electronically-controlled center differential lock.
The "Viscomatic" unit - central viscous coupling locking epicyclic unit located near the rear axle and Torsen rear differential.
The Viscomatic was developed by Alfa-Romeo in collaboration with Steyr-Puch. This is a further evolution of the device that was previously used on the Proteo.
Figure: Alfa-Romeo 164 q4 rear differential housing with Viscomatic central differential unit. (62KB)
Figure: Gearbox with power takeoff to the rear wheels (102KB)
Figure: All wheel drive control diagram (74KB)
AWD system available only with the 3.0 V6 gasoline engine.
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33 4x4 (1983-1991)Next
Part-time all wheel drive.
The 33 4x4 made its debut in 1983. The layout adopted for this compact saloon meant that the rear wheel drive had to be engaged by means of a lever in the passenger compartment. It also offered higher ground clearance than front wheel drive cars.
In 1990 the 33 4x4 was fitted with an electromagnetic coupling who disengaged the rear axle during safety braking to avoid interferences with the ABS system. The lever was replaced by an electric switch.
Figure: Alfa Romeo 33 4x4 (168KB)
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33 Permanent 4 / Q4 (1991-1995)Next
Full-time all wheel drive.
In 1991, the Alfa 33 was fitted with a sportier interpretation of the four wheel drive concept. The transmission layout of the new Permanent 4 (this was the name of the version) was more complex than its predecessor: drive is transmitted to the viscous coupling from an electromagnetic coupling normally engaged and controlled by an electronic control unit which automatically disengages during high decelerations (safety braking).
In 1994 the car was renamed 33 Q4.
Figure: Alfa Romeo 33 Permanent 4 (811KB)
Figure: Alfa Romeo 33 Permanent 4 (125KB)
Figure: Alfa Romeo 33 Permanent 4 viscous coupling (133KB)
Figure: Alfa Romeo 33 Permanent 4 (106KB)
Figure: Alfa Romeo 33 Permanent 4 transmission (96KB)
Figure: Alfa Romeo 33 Permanent 4 - Safety braking system (150KB)
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Matta AR51 (1951)Next
First Alfa Romeo to feature 4WD.
Do you own Alfa-Romeo Matta Ar51 (1951)? Can you please make a photo of the car's 4x4 transmission, switches, dashboard lights, etc. and send it to ?