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Info - MN4 (4T40-E) MN5 (4T45-E) Engineering Changes

Subject:MN4 (4T40-E) MN5 (4T45-E) Engineering Changes

Models:1995-2003 Chevrolet Cavalier
1997-2003 Chevrolet Malibu
1997 Oldsmobile Achieva
1997-1999 Oldsmobile Cutlass
1998-2002 Oldsmobile Intrigue
1999-2003 Oldsmobile Alero
1995-2003 Pontiac Sunfire
1997-2003 Pontiac Grand Am
with 4T40-E (MN4) or 4T45-E (MN5) Automatic Transmission



Engineering changes have been incorporated into the MN4 and MN5 Reverse Clutch Housing and related parts beginning with transmission assemblies produced on December 4, 2002, Julian Date 02 338. Refer to the following list for the affected parts and a description of how each changed:

    • The new Reverse Clutch Center Seal has a larger feed orifice.
    • The new Reverse Clutch Snap Ring is thicker and stiffer.
    • The new Reverse Housing Snap Ring Grove is wider to accommodate the thicker snap ring.
    • Elimination of the Backing Plate Selectives. The new clutch assembly is built with only the thickest of the three previous selective backing plates.
    • The new Reverse Wave Plate is stiffer.

Notice: To maintain proper operating calibration of the transmission, determine which Reverse Clutch Housing, Center Seal, Snap Ring, Backing Plate and Wave Plate to use according to the Julian date on which the transmission was assembled. Failure to use these parts as instructed will cause improper function, shift feel, and possible transmission distress. The affected service kits include an instruction sheet that details the difference between the 1st and 2nd design center seals, and how to determine which to use.