6L90 (One-Piece) 4-5-6 Billet Shaft & Hub for use with stock dimension clutches (36 tooth clutches) & 4-5-6 Clutch Kit - Level 2.5

Recommended Transmission Tools

• Transmission holding fixture
• Calipers
• Dial Indicator Set
• Bushing Drivers & Arbor Press for Bushing Installation (Bushings should only be replaced as needed)
• Sealing Ring Protector and Sizer
• Various Clutch Spring Compressors
• Output Carrier/Shaft Lifting Tool
• 1-2-3-4 & 3-5-R Clutch Housing Installer
• Large Snap-Ring Pliers
• Pump Alignment Tool

Misc. Transmission Information

Upgraded Parts If you have an early pump cover (stator) that does not utilize anti-rotational tabs on the sealing rings or an early 1-2-3-4/3-5-R clutch housing that does not have the matrix stamp, you will need to install a factory-upgraded pump cover and clutch housing.

Transmission Tuning Please understand that proper tuning of the TCM and ECM is mandatory. All 6L80/90’s are torque-based shifted units. The torque signal is calculated through the ECM. Therefore, transmission performance & longevity are directly dependent on the delivered torque signal that’s calculated in the ECM. If this is not done properly, you will experience premature transmission failure. We also do not recommend maxing out pressures or deleting torque management completely because it will cause seal failure and/or hard part breakage.

Flushing Cooler & Lines We cannot stress enough the importance of flushing the transmission cooler(s) and lines, even if they are new. We recommend using a Hot Flush Machine Flush Machine or something comparable.                                      

Auxiliary Cooler You need to install a stacked plate auxiliary transmission cooler (not a tube and fin style cooler) rated for 25,000 GVW. The ideal operating temperature for this transmission is 180°or less. These transmissions tend to run very hot, so the cooler will lower the operating temperature and recovery time, which in turn will extend the life of your transmission.

Transmission Rebuild Kit Warranty

Limited Warranty Statement

Circle D's Transmission Rebuild Kits carry a 1 year, parts-only warranty, exclusively against manufacturer’s defects. The warranty period begins at the date of purchase. There is no warranty under the conditions listed below. This includes, but is not limited to:

• Improperly Stored
• Improperly Installed
• Improperly Tuned (EMC or TCM)
• Misapplication
• Altered, either by Owner or Their Technician
• Torque Converter Failure
• Inadequate Flushing of Transmission Cooler
• Improper Fluid Level
• Water/Engine Coolant in Transmission
• Excessive Power
• Accident
• Neglect

Circle D Transmission will not pay for any fluids replaced in the event of a Kit failure.

Under no circumstances shall there be any labor warranty or other warranty coverage on Circle D Transmission Kits beyond the replacement of individual Kit components. We will not provide you with any cash refund except as may be required by law. Consequential and incidental damages are not recoverable under this warranty and are expressly excluded.

There is no warranty on broken parts such as, but not limited to, twisted splines, broken shafts, or broken planetaries.

Warranty issues will be considered on an individual basis.