Volvo S70

The development of the C70 coupe and convertible in the late 1990s heralded not just a new design direction for Volvo, but also new model nomenclature across its lineup: C for Coupe/Convertible, S for Sedan, V for station wagon, and XC for "Cross Country" SUVs and lifted wagons.

Coinciding with this change was a "facelift" for the P80-based 850 sedan and wagon, with both stylistic and technical updates to keep them competitve. Thus, the revised 850 sedan debuted in 1998 as the S70, slotting in to Volvo's lineup under the flagship S90.

As with the preceeding 850, the S70 came with an all "white block" five cylinder engine lineup in the USA, featuring naturally aspirated 2.4L (2.5L in some early cars), light-pressure turbo 2.4L "GLT", or high-pressure turbo 2.3L "T5" gasoline engines. Power got to the ground either through either 5-speed manual M56, 4-speed automatic AW50-42/43, or (in 2000 and on naturally aspirated cars only) AW55-5X SN 5-speed automatic transmissions. 

The S70 and V70 saw lots of under-the-skin changes as Volvo rapidly modernized going in to the new millenium. Motronic ME7 engine management in 1999 brought "throttle by wire", with throttle actuators and position sensors replacing physical throttle cables. These late P80s are "partial network" cars which use multiple Electronic Control Units communicating on a common network to control many of the car's functions.

For the first time in Volvo's history, these later P80 cars came with the option of AWD, with a viscous coupling in the rear of the car engaging the rear wheels when the front wheels start to slip. Inside the coupling, alternating discs attached to the front axle and rear axle parts of the driveshaft spin through a silicone oil based dilatant fluid. These special fluids are "shear-thickening", so when there's a speed difference between the axles (such as the front wheels slipping on ice or gravel), the discs spinning past each other heat the fluid due to fluid friction, the fluid thickens as it warms and makes the plates stick together, and the now-locked coupling engages the rear wheels.

Only automatic LPT S70s from 1999 came with AWD, so it was much more common to find V70s and V70 XCs with AWD.

AWD faults are typically due to problems in one of three areas: the "angle gear" or "bevel gear" bolted to the side of the transmission, the "collar" or "sleeve" that connects the angle gear to the transmission, or a breakdown within the viscous coupler itself. The angle gear can have its oil and seals changed to prolong life, and the sleeve can be replaced with the angle gear and passenger (right) front axle out of the way, but the VC is a sealed unit and people tend simply to source used replacements when they fail.

Being, fundamentally, a facelift of the almost decade old P80 platform instead of an all-new model, the S70 and the V70 only had three years before their 21st century replacements, the P2-based, fully-networked S60 and V70, appeared in 2001. Though these late P80s have more in common with the later all-digital Volvos, they're still remembered fondly in some circles as the last of the classic "boxy" Volvos.

Model information is based on the USA vehicle market. Other model variations may exist outside the USA.