General Motors 10L80 / 10L90

General Motors' longitudinal ten-speed — in the Camaro, Silverado, Tahoe, Yukon, Escalade and Corvette.

It is the same design as Ford's 10R80, developed jointly by the two companies and built separately by each. That is worth knowing because it roughly doubles the literature: a great deal written about the Ford unit describes this one, and a reader who searches only "GM 10-speed" finds half of what exists.

Most of what is reported about it is the ratio count. Ten gears means near-constant changing and hunting between the tall ones on a light throttle; that is behaviour, and driving another example of the same model settles it faster than a scan tool.

Its own recurring complaints are a harsh 1–2 change, a clunk downshifting to a stop, and a hesitation when rolling back onto the throttle. These respond to adaptation and to software much more often than to parts, and GM has issued updates for exactly them.

The genuine fault is the torque converter's lock-up clutch, felt as a shudder at light throttle — and as on every recent GM automatic here, the fluid is the first thing to establish and, historically, GM's own remedy.