The General Motors 8L family of transmissions has been in service since 2014, gradually replacing older 6L six-speed units across much of the company's lineup. The bigger 8L90 was the first GM 8-speed transmission, and it debuted in the 2015 Chevrolet Corvette C7 Stingray, while the smaller 8L45 debuted in the 2016 Cadillac CT6. Not long after, the 8L family of transmissions expanded its reach to many other GM products.
The 8L90 was designed to handle more torque and is the heavy-duty, reinforced
version of the 8L, meaning it is used in models like the Chevy Silverado, GMC Sierra, or the Corvette. The 8L45 is comparably lighter and more efficient, making it a better fit for vehicles such as the Cadillac CT6, Chevy Colorado, or the GMC Canyon. Even though the 8L family of transmissions is widely adopted and very sophisticated, it has not been immune to problems.
The most prevalent problems include noticeable jerkiness, gear slippage, hesitation, and shuddering — problems also seen in the Chevrolet 10-speed transmission that came after it. As a result, the 8L transmission family has become a frequent topic of discussion in technical service bulletins (TSBs) and owner forums, and that is exactly what we are going to cover next.
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What Goes Wrong On The GM 8L Transmission?
According to AutoBlog, 39 owners from 26 different states filed a class-action lawsuit against GM: Claiming that as many as 800,000 vehicles equipped with the 8-speed automatic transmission experience hesitation, significant shakes, shuddering, jerking, clunking, or hard shifts. If these issues were ever to result in an official GM recall, it could be one of the biggest transmission recalls in recent history.
Next Gen Drivetrain describes the torque converter within the GM 8L as "uniquely untrustworthy" due to the poor functionality of the clutch design. The lock-up clutch assembly in front of the converter isn't designed for anything more spirited than normal driving. As a result, towing, hauling, or hard accelerations can lead to long-term issues and accelerated wear and tear.
Owners have also reported problems with transmission fluid breakdown, which can also cause the transmission to shudder, clunk, or shift harshly. These weren't the only widely reported problems, as Road and Track reports that the same lawsuit also recognized valve body design defects, which can cause the vehicle to shake or shudder at higher speeds.
Solutions For GM's 8L Problems
In August 2019, GM introduced the 18-NA-355 technical service bulletin in order to combat both of the torque converter problems mentioned above. The TSB states that a full flush of the torque converter fluid should be performed using Mobil 1 LV ATF HP fluid, which has been specifically designed to deal with this issue. Later on, GM also introduced the 20-NA-142 TSB in January of 2023, which aims to resolve the shuddering via a complete torque converter replacement.
GM also addressed the valve body problem with the PIP5437A TSB from November of 2016, which recommends a transmission teardown and repair if debris is found. If no debris is present and the issue persists, GM advises replacing the complete valve body. Lastly, Reuters reports that in June 2025, a federal appeals court decertified the nationwide class-action suit, citing too many differences in vehicle models, state laws, and customer experiences, and thus handing a symbolic victory to GM.
On the other hand, within one of the related legal developments; Wilkinson, the U.S. District Court for the Eastern District of Michigan, denied GM's motion to compel arbitration and thus allowed the plaintiff to proceed with litigation in court rather than private arbitration, as GM had sought. While it may be a narrow win for the plaintiff, it represents a meaningful opening for continued legal action against GM. Only time will tell how these issues and their solutions will evolve, both in the court of public opinion and the court of law.
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