6L90E 2WD

About 8L90 Transmission

The GM 6L90 is a heavy-duty 6-speed automatic transmission developed as a stronger version of the 6L80. It is designed to handle higher torque, heavier vehicles, and demanding driving conditions in trucks, SUVs, and performance builds.

It features reinforced internals, a wide gear ratio spread, and advanced electronic control for smooth shifting and long-term reliability. The 6L90 is commonly used in GM trucks and SUVs where durability and towing strength are essential.

At Gearstar, we custom-build and upgrade GM 6L90 transmissions to match your exact power level and application. Every custom-built 6L90E includes a compatible controller for precise shift performance and seamless engine integration. From towing rigs to high-horsepower street cars, Gearstar's 6L90 units are engineered for serious performance and long-term reliability.

Specifications of GM 6L90 Transmission

6-speed automatic with wider gear ratio spread (6.04 overall)

Gear ratios: 1st: 4.02, 2nd: 2.36, 3rd: 1.53, 4th: 1.15, 5th: 0.85, 6th: 0.67, Reverse: 3.06

Torque capacity: 440 ft-lb engine input, 885 ft-lb output (220 ft-lb jump over 6L80)

Length: 1-3/8"" longer than 6L80, ~25% internal parts differ

Output shaft: 29 spline (most trucks), 36 spline (HD/vans)

Weight: ~195 lbs dry, up to ~230 lbs full

Fluid: Dexron VI, 10–12.6 quart capacity

TCM: 32-bit adaptive learning computer integrated into the valve body

Key Features of the GM 6L90 Transmission

• These upgrades make the 6L90 ideal for high-performance vehicles and workhorses under even the toughest conditions.
• Heavy-Duty Construction: Reinforced internals and a strong case improve durability under heavy load and high-stress use.
• Wide Gear Ratio Spread: 4.02 first gear and 6.04 overall spread for strong launch performance, better towing, and efficient highway cruising.
• Upgraded Clutch Packs: Raybestos GPZ friction materials improve shift quality and extend service life under demanding conditions.
• Improved Hydraulic Control: Better line pressure regulation and sealing help reduce leaks and prevent clutch wear.
• Stronger Reverse Engagement: Improved reverse gear operation for smoother and more reliable shifting.
• Torque Converter Compatibility: Supports 258mm and 300mm high-stall converters for improved towing and performance response.
• Integrated Control System: Advanced TCM integration with adaptive learning for more precise and consistent shifting.
• Built for Demanding Use: Designed for long-term durability in daily driving, towing, and performance applications.
• Compatible Vehicles for the 6L90 Transmission
• Chevrolet Silverado (select models)
• GMC Sierra (select models)
• Chevrolet Corvette (select models)
• Chevrolet Camaro (select models)
• Cadillac Escalade
• Cadillac CTS / CTS-V (select models)
• GMC Yukon / Yukon Denali
• Chevrolet Tahoe
• Chevrolet Suburban

Advantages of the GM 6L90 Transmission

• The 6L90 combines strength, smooth shifting, and modern electronic control. It adapts shift timing based on driving style, delivering smooth cruising and strong acceleration when needed.
• A properly built 6L90 can handle significantly more power than stock, making it a top choice for trucks, SUVs, and performance builds.
• Key benefits include
• Strong towing capability for heavy loads
• Wide torque converter options for custom tuning
• Electronic tuning support with aftermarket controllers
• Proven long-term durability in high-mileage use
• Strong 4.02 first gear for quick launch
• Efficient 0.67 overdrive for highway fuel savings
• Reinforced clutch and pump systems for reliability
• Custom-built single-technician assembly
• Dyno-tested before shipping
• 6L90 Weak Points and Their Fixes
• The 6L90's 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 when shuddering, slipping, or delayed engagement under towing or spirited driving. Billet-cover torque converter with upgraded clutch material fixes this failure.
• Valve body wear due to erratic shifting, harsh gear changes, and pressure leaks. It is fixed by the Sonnax Zip Kit to seal critical circuit pressure losses
• Pump alignment issues when improper rebuild alignment causes pressure loss or premature wear. A selective pump thrust washer, proper alignment during assembly solves the alignment issues
• Clutch pack degradation due to 3-5 Reverse and 4-5-6 Z Pak failures under extreme loads. GPZ friction modules and a heavier-duty 4-5-6 backing plate fix this issue.
• Gearstar's custom-built units address each weak point at the component level before assembly to ensure truck, SUV, and performance builds receive application-specific upgrades rather than generic fixes.
• Why Builders Buy a Custom-Built GM 6L90 From Gearstar?
• When it comes to custom-built high-performance transmissions, Gearstar stands out as an industry leader.
• 1. Precision Engineering and Customization
• A single master technician makes each 6L90 transmission. Gear ratios, clutch plate configurations, and torque converters are all tailored to your application, such as towing, hauling, racing, or cruising.
• 2. Premium Components and Proven Reliability
• We use only top-tier parts built with heavy-duty components:
• Heavy-Duty Pumps with a selective thrust washer
• Reinforced Clutch Assemblies (3-5 Reverse Z Pak + 4-5-6 Z Pak)
• High-Performance Friction Materials (Raybestos GPZ, outperforms OE by 20%)
• Calibrated Valve Bodies with Sonnax Zip Kit sealing critical pressure circuits
• These 6L90E transmission upgrades deliver better performance, reduced wear, and longer transmission lifespan.
• 3. Built for Real-World Demands
• Gearstar transmissions aren't just dyno-tested, they're tested for real-world conditions. Our customers consistently report:
• Smooth towing of loads over 10,000 lbs
• 200,000+ miles of trouble-free performance
• Improved fuel efficiency and throttle response
• 4. Customer Satisfaction and Support
• From start to finish, we deliver a personalized experience. Whether upgrading a high-performance vehicle or replacing a failing transmission, we work closely with you to ensure a perfect fit and optimal performance. We back our work with industry-leading warranties and customer support.
• Buy a Custom-Built GM 6L90 Transmission for Sale
• Whether upgrading your current GM vehicle or planning a custom swap, a Gearstar 6L90 delivers power, reliability, and performance you can trust.
• Contact us today to discuss your build or browse our selection of custom-built 6L90E transmissions for sale.