Race-Calibrated Servo Return Spring Kit
OE Part No: 3830235, 3815914, 3830235
- Shims (2)
The servo return spring is the source of many "mystery" band failures caused by inconsistent servo release and weak springs prone to collapse. Sonnax race-calibrated servo return spring kit 28133-HD for Powerglide units ensures optimum servo function in high gear for longer band life, cooler transmission and tunability of shift.
Designed to overcome the pin bias effect, the Sonnax race-calibrated spring has higher seat pressure to help ensure full servo release, but with a lower rate for greater net apply force. Watch this video to see exactly how the servo performs at high pressures when fitted with an OE, light aftermarket or Sonnax race-calibrated spring.
- Specifically designed to work with line pressures from 200 to 275 psi
- Includes two .050” shims to aid in tuning at higher line pressures