Subaru TR690 (Lineartronic)

Subaru's CVT — in the Legacy, Outback, Ascent, WRX and most of the range since 2009.

It is a chain CVT, not a belt one, and that is the first thing worth knowing. Almost every other CVT on this site — Jatco's, Toyota's, Honda's — drives through a steel push-belt; Lineartronic uses a chain, which is why Subaru could put one behind a turbocharged engine and all-wheel drive when the belt units of the time could not take it.

Its longitudinal layout is the second difference. Every other CVT here is transverse; this one sits in line with the engine because Subaru's flat engine and symmetrical drivetrain require it. A procedure or a part from any other CVT does not describe it.

Its recurring complaint is a shudder or a hesitation from rest, and on a CVT the useful question is whether it changes with temperature. A shudder that is worst when cold and clears as the car warms is very often the torque converter's lock-up clutch; one that appears under load at speed, with the engine rising and the car not, is the chain and pulleys.

Fluid is the whole of the maintenance and the whole of the risk. A CVT's clamping force is hydraulic, and aged fluid loses clamping before it loses anything else — felt as a slip under acceleration long before any noise. Subaru's CVTF is specific, and a car that tows or climbs regularly has aged it faster than the odometer suggests.