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SON-28821-10K – Sonnax “Smart Tech” Ratio Style Powerglide Servo Kit

The SON-28821-10K is the Sonnax “Smart Tech” ratio style Powerglide servo upgrade system. Sonnax designed this system to address and solve the “pin bias” issue with the original GM design Powerglide servo system. The unique design has the same apply area as the OE Powerglide servo, but increased release area so the servo is hydraulically released like other modern servos. The hydraulic release means a lighter return spring can be used with the system, yielding more band apply force over a standard design servo at the same line pressure.

Some of the key features / benefits associated with the SON-28821-10K are as follows:

  • All-in-one kit makes it easy to install a state-of-the-art servo system.
  • Supported servo design eliminates piston binding.
  • Significantly lighter spring prevents staging issues and backing up when trans brake is applied.
  • Prevents input shaft failure due to tie-up on shift.
  • Allows greater tuning of high clutch apply to prevent tire spin and pedaling after the shift.
  • Delivers more total net apply force than any stock-sized servo.
  • Eliminates need to calibrate servo return spring to line pressure or varying case depth.
  • Improved sealing throughout reduces fluid loss and is optimized for low friction movement.
  • Low-profile design ensures adequate clearance.
  • 6061 Anodized billet aluminum cover.

We use the SON-28821-10K standard in our 1300 horsepower and above builds and offer it as an upgrade in any build we do.  We are also offering the SON-28821-10K with free ground shipping to a continental US address.