Performance TransmissionCircle D Transmission is excited to announce that we are now offering High Horsepower 6L80 (6L80e) and 6L90 (6L90e) Performance Transmission Rebuild Kits and Parts. We offer FREE UPS Domestic Ground Shipping. Most orders ship the same day if ordered by 12pm, Central Standard Time, Monday through Friday.

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CDT’s Kits are available in multiple horsepower levels:

  • 6L80 (6L80e) Level 2 Rebuild Kit rated up to 550 RWHP

  • 6L80 (6L80e) Level 3 Rebuild Kit rated up to 750 RWHP

  • 6L80 (6L80e) Level 4 Rebuild Kit rated up to 1000 RWHP

  • 6L90 (6L90e) Level 2 Rebuild Kit rated up to 600 RWHP

  • 6L90 (6L90e) Level 3 Rebuild Kit rated up to 750 RWHP

  • 6L90 (6L90e) Level 4 Rebuild Kit rated up to 1100 RWHP

CDT began the journey of taking the factory GM transmission and transforming it so that it could handle the horsepower revolution present today when we purchased a Gen 5 Camaro for R&D. Along the way, there were many requests from fellow horsepower junkies to purchase CDT’s revolutionary Performance Rebuild Kits for the 6L80 (6L80e) & 6L90 (6L90e.)

These Rebuild Kits have the necessary components to dial in your transmission rebuild correctly - from hydraulics to clutch clearances to transmission end-play. Included in each Kit is valuable information pertaining to transmission assembly tips and detailed CDT rebuild instructions. These kits pick up where GM left off in terms of strengthening the OE transmission to handle the ever-increasing horsepower levels of today’s vehicles.

Besides offering the complete rebuild kits for the 6L80 (6L80e) and 6L90 (6L90e) we also offer individual components. One of our more popular parts is the 4140 H.T.S.R. (Heat Treated and Stress Relieved) Billet Reinforced Output Carrier – also known as the Billet Planetary. It includes a 4140 billet steel drive to strengthen the spline area. The drive plate is milled and contoured to the planetary housing to eliminate any possible separation under a load. This is a drop-in part for vehicles producing over 750 RWHP and also for Nitrous and/or Heavy Vehicles including trucks, SUV’s and CTS-V’s.

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Another popular option is the Billet Shaft, Hub and 4-5-6 Clutch Kit for both the 6L80 (6L80e) and the 6L90 (6L90e.) The billet intermediate shaft is made to our specifications to address the weak stock shaft issue, is precision machined from 300M alloy steel and is heat-treated to add strength and durability. The 4-5-6 Clutch Hub is also manufactured to address the weakness in the stock hub while at the same time it improves lubrication to the 4-5-6 clutch module. It is made from 4140 H.T.S.R. billet steel. Our 4-5-6 clutch modules increase apply area and the G3® friction material is formulated to maximize heat resistance and minimize wear to the clutch module.