INTENSE™  Gear Ratio Conversion Kits

INTENSE™ Gear Ratio Conversion Kits


Part Number: GCK-3xx

Shipping Weight: 7.00 pounds

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Product is no longer available. Parts were based on sprockets from a 4T60E, which stopped production around 2005. Supplies for the sprockets are exhausted and thus we cannot make more. Page is kept on the site for reference purposes.


  • 2000-current Impala
  • 1998-current Grand Prix GT
  • 1998-current Monte Carlo
  • 1998-current other applications using the 4T65E (non -HD) transaxle
  • 1997-current Grand Prix GTP
  • 1997-current Regal GS
  • 1997-current Bonneville SSEi
  • 1997-current other applications using the 4T65E-HD transaxle

Many people have expressed interest in the heavy duty drive sprocket/chain setups we use in all INTENSE™ Transaxles so we’ve assembled some kits for hardcore do-it yourselfers.

INTENSE™ Gear Ratio Conversion Kits use 3/4" spur gear sprockets, instead of the stock 180 degree offset double chain and gears. Each Gear Ratio Conversion Kit includes the appropriate drive sprocket, drive sprocket thrust washer, driven sprocket, 7/8" drive chain, and all the machining required to make these gears fit your otherwise stock 4T65E or 4T65E-HD transaxle. Optionally, you can add the accessory kit which includes channel plate gaskets, valve body spacer/gasket and fluid scoop.

For the 1997 model year, GM switched to an offset double drive chain design in an effort to reduce noise. The offset double drive chain has two sets of links out of phase by a half link (or 180 degrees). As one link starts to engage a sprocket tooth, another link starts to disengage. The engage and disengage noises are acoustically opposite, so they virtually cancel each other out. INTENSE™ Transaxles use 3/4" spur gear sprockets with a 7/8" chain (same as in this gear ratio conversion kit), instead of the stock 180 degree offset double chain and gears. Because of this, our transaxles have a barely perceptible whine in First and Reverse, but a major weak link is eliminated. Our gear conversion kits come with a new ISS reluctor wheel already attached to the drive gear by loc-tite'd screws replacing the stock rivets that could break or enlongate the ISS reluctor wheel holes.

Stock 4T65E transmissions typically came with a 3.29:1 ratio in the W-body platform with naturally aspirated engines.  Supercharged W-body cars typically had a 2.93:1 ratio with the 4T65E-HD transmission.  You'll find that most supercharged cars benefit from the 3.29 ratio upgrade.  Naturally aspirated cars work best with a 3.69 ratio.  We don't recommend 3.69 for supercharged cars as keeping the tires engaged is exceptionally difficult in the lower gears and makes the car unpleasant to drive on the street or all but the most hardcore track setups.

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