Description
Powerglide Servo Piston Return Spring, Sonnax 28133.
The inconsistent or weak servo return springs cause many band failures. Sonnax servo piston return spring 28133 for GM Powerglide units is a lighter-than-stock spring ideal for low line pressure applications of 175 psi or less.
If the servo encounters an application with more than 175 psi pressure, it may fail to fully release, causing the spring to drag and burn the band due to the pin bias effect. In higher pressure applications, Sonnax 28133-HD is used.
