General Motors 6L80 / 6L90 / 6L45
6-speed automatic · longitudinal · 2006–2020
Also known as: 6l80, 6l90, 6l45, 6l50, hydra-matic 6l, gm 6-speed longitudinal, 6l80-e, 6l80e
General Motors' longitudinal six-speed — in the Corvette, Camaro, Silverado, Sierra, Tahoe, Escalade, Commodore and, as the smaller 6L45, in BMW's E87 and E90.
Its characteristic failure has a name and a very specific symptom: the 3–5–reverse wave plate. The plate fractures, and the transmission loses third, fifth and reverse together while first, second, fourth and sixth still work. That combination is the diagnosis — no other common fault takes exactly those three, and a car that drives forward normally but will not reverse is not a linkage problem.
GM revised the plate, so which one a unit contains decides whether the repair is a rebuild or a replacement, and a transmission that has already been apart may or may not have received it.
Torque converter shudder is the other recurring complaint — a light vibration under gentle throttle at low speed, often described as driving over rumble strips. It tracks fluid condition closely, and on this unit a fluid change is a diagnostic step rather than only maintenance.
The 6L45 in a BMW is the same family and a different size. Parts and capacities differ, and a procedure written for a Silverado's 6L80 does not describe it.
Cars fitted with this gearbox
27 generations. Only where a source names the model and the generation together — a gearbox is documented as a product far more often than as a fitment, so this list is deliberately shorter than the truth.
Chevrolet
Hummer
Pontiac
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about 6L80 / 6L90 / 6L45.