8L90

About 8L90 Transmission

The GM 8L90 (commonly called 8L90E) is an 8-speed automatic developed by GM for rear-wheel-drive and performance vehicles. It features a 4.56 first gear, close gear steps, an integrated TCM, and adaptive shift control. Factory units handle ~650–700 hp; with Gearstar upgrades (reinforced clutches, hardened shafts, performance torque converter), it reliably supports higher power for street/track builds.

Introduced by GM in 2014, the 8L90 transmission replaced the 6L90 in many performance applications with two additional gears for improved acceleration, drivability, and fuel efficiency.

At Gearstar, we custom-build and upgrade GM 8L90 transmissions to exact power levels and include a compatible transmission controller for optimal shift performance and seamless engine integration. From high-horsepower street cars to track-ready builds, Gearstar’s 8L90E units deliver durable, precise performance.

Specifications of GM 8L90

Gears: 8 forward + 1 reverse

First gear: 4.56

Overall ratio spread: ~7.0

Case: die-cast aluminum, integrated bell

Weight: ~195 lb (some sources list ~218 lb)

Max gearbox torque (GM estimate): 665 lb-ft

Converter size: 258 mm, turbine damper

Fluid: DEXRON High Performance ATF, ~10.3 L capacity

Max engine power (GM estimate): 420 hp; max engine torque: 460 lb-ft

Applications: LT1 (slip-yoke) and LT4 (fixed-yoke) variants

Key Features of the GM 8L90 Transmission

• 8-Speed Design with 4.56 First Gear: Provides strong acceleration from a stop and lower RPMs for comfortable highway cruising.
• Lightweight and Strong Construction: Reduces rotating mass for improved efficiency and maintains durability.
• High Torque Capacity: Supports up to 700 HP with upgraded internal components designed for demanding performance use.
• Integrated TCM and Enhanced Cooling: Delivers precise transmission control and helps keep operating temperatures in check.
• Adaptive Shift Technology: Learns driving habits and automatically adjusts line pressure and shift timing for smoother, more responsive performance.

Advantages of the GM 8L90 Transmission

• The GM 8L90 offers a great balance of strength, smooth performance, and modern electronic control. Its adaptive shift system adjusts shift timing based on driving conditions, which delivers smooth cruising and quick response when extra power is needed. When properly built, the 8L90 can handle much more power than a stock unit. The 8L90 is also a popular choice for LS and LT engine swaps due to its strength, compact design, and electronic tuning flexibility.
• Key benefits include
• Wide Torque Converter Options: Available with different stall speeds to match your vehicle and driving style.
• Electronic Tuning Capability: Can be tuned with aftermarket controllers for improved performance and customization.
• Proven Durability: Built to perform reliably in high-mileage and high-horsepower applications.
• 8-Speed Design: Close gear ratios provide smooth shifts and consistent power delivery.
• Strong 4.56 First Gear: Delivers quick launches and strong acceleration from a stop.
• Lightweight Construction: Helps improve efficiency and supports faster gear changes.
• Integrated TCM and Enhanced Cooling: Provides accurate control and better temperature management.
• Multiple Output Options: Available in slip-yoke and fixed-yoke configurations for a wide range of vehicle setups.
• Improved Fuel Economy: Tall overdrive gears help reduce engine RPM during highway driving compared to older 6-speed transmissions.
• Vehicles Have the GM 8L90 Transmission
• Chevrolet Corvette (C7), Camaro SS/ZL1
• Cadillac CTS-V, Escalade
• Chevy Silverado 1500 (select trims), GMC Sierra 1500, Sierra Denali
• Performance-oriented SUVs and luxury sedans across GM’s lineup
• Common GM 8L90/8L90E Problems & Fixes
• The GM 8L90's broad strengths don't mean it's bulletproof in stock form. Common failure areas can be addressed with upgraded internals and application-specific components.

Common weak points include:

• Torque converter failure under towing or spirited driving, as the factory converter uses thin lockup material and can shudder, slip, and contaminate fluid
• Valve body & pressure loss when internal pressure leaks cause delayed shifts, harsh engagement, and long-term clutch damage
• Overheating under load when 8L90 runs hot by design; without proper cooling, fluid breakdown happens fast, especially in trucks and SUVs
• For 8L90E transmission 4x4 applications in trucks and SUVs, thermal stress and torque demand accelerate these issues significantly. A properly upgraded unit with hardened internals, improved clutch packs, and a quality valve body transforms the 8L90 into a transmission that handles real-world punishment.
• Gearstar's custom-built units address each weak point at the component level before assembly, ensuring F-Body, truck, and SUV builds receive application-specific upgrades rather than generic fixes.
• Gearstar Upgrades for 8L90 Transmission Performance
• When you buy an 8L90E transmission for sale from Gearstar, your unit includes application-specific upgrades that address known weak points and boost durability:
• Upgraded clutch packs for higher torque and performance applications
• Hardened shafts and reinforced internals to reduce flex/failure under load
• Performance torque converter (billet cover, upgraded clutch material) to eliminate shudder and improve lockup
• Precision-calibrated valve body with corrected hydraulic circuits for consistent pressure and shift quality
• Improved cooling strategy and tighter clutch clearances to reduce overheating under towing or track use
• Included a compatible controller for precise shift timing, TCC lockup, and line pressure management
• Why Builders Choose Gearstar for 8L90 Transmission
• An 8L90 remanufactured transmission replaces worn clutches and ships out. Gearstar’s custom-built GM 8L90 transmission for sale is:
• Stripped to bare case; all wear items replaced
• Built by a single master technician
• Known GM weak points upgraded at the component level
• Matched billet torque converter included
• DYNO-tested before shipping
• Covered by a multi-year warranty
• Buy a Custom-Built 8L90E Transmission from Gearstar
• Whether you’re upgrading your current GM vehicle or planning a custom swap, a Gearstar 8L90 transmission delivers the power, reliability, and performance you need.
• Contact us today to discuss your build or browse our selection of custom-built 8L90E transmissions for sale.