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6L90 Performance Clutch Module - Level 2

Detailed Instructions Included | FREE UPS Ground to the contiguous United States (lower 48)

Kit is designed with stock dimension 36-tooth 4-5-6 clutch plates and will work with the OE intermediate 4-5-6 clutch hub. The 4-5-6 clutch pack provides 14% more surface area than a stock clutch set up. The 3-5-R clutch pack offers 20% more clutch area than stock.
Availability: In stock
In stock items ship within 1-2 business days.
Picture for representation purposes only. Actual contents may vary as we continue to develop our products.

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CDT456L2/90-CM (4-5-6 CLUTCH MODULE)
8 Borg Warner® Clutches
7 Lindered Steel Plates 
1 Apply Plate
1 Backing Plate
1 Snap Ring
2 Bonded Pistons

CDT456L2/90-CM offers 14% more clutch apply area than stock. Lindered is a chemical and heat treatment process that hardens the steel, which results in less wear.

6 Borg Warner® High Energy Clutches
7 Kolene® Steels (varying thickness) 
1 Backing Plate
1 Snap Ring

CDT35RL2/90-CM offers 20% more clutch apply area than stock. High Energy material maintains consistent frictional behavior and tolerates extreme thermal stress applications. Kolene steels provide a surface treatment that enhances wear & fatigue resistance.

6 Borg Warer® Clutches
6 Steels
1 Snap Ring

CDT1234L2/90-CM (1-2-3-4 CLUTCH MODULE)
6 High Energy® Clutches
6 Steels
1 Snap Ring
1 Spiral Snap Ring
1 Snap Ring Kit

High Energy material maintains consistent frictional behavior and tolerates extreme thermal stress applications. 

6 High Energy® Clutches
6 Steels

High Energy material maintains consistent frictional behavior and tolerates extreme thermal stress applications. 


PLEASE NOTE: GM has a transmission that has the same outside dimensions as a 6L90 but uses one less clutch in all the clutch housings compared to a true 6L90. We call this transmission a 6L90LCC (less clutch capacity.) We also sell a performance kit that accommodates this transmission. Please refer to "Stock Clutch Capacity Chart" and "Length of Main Case Chart" on the "Transmission Specs" tab below to determine if you have a 6L90 or 6L90LCC.


transmission specs worksheet

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 are mandatory. All 6L80/90’s are torque base shifted units. The torque signal is calculated thru 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 & fin style cooler) rated for 25,000 GVW. The ideal operating temperature for this transmission is 180°or less. These transmissions have a tendency to run very hot – the cooler will lower operating temperature and recovery time which in turn will extend the life of your transmission.

  • 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

Limited Warranty Statement

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

Improperly Stored
Improperly Installed
Improperly Tuned (EMC or TCM)
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

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 many 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.