Sonnax Servo Cover Kits 28821-03K and 28821-06K are designed to replace other covers and require no modifications to the case. They can be installed with servo piston kits 28821-01K or 28821-02K.

Sonnax Master Servo Kits 28821-04K and 28821-07K are designed to replace the piston and cover and require no modifications to the case. The kits feature the no leak dual O-ring servo using two O-ring seals for superior, positive sealing. In applications with a distorted bore or case flex, O-rings will conform to the bore surfaces, a feature not possible with metal sealing rings. Precise slip fit with apply pin further improves performance.

In addition, Sonnax Master Servo Kits 28821-05K and 28821-08K are designed to replace the piston and cover and accept either two PTFE seal rings or two OE metal sealing rings. Made with the same high-quality billet aluminum as our dual O-ring servos, these servos will give you the positive apply needed in high pressure racing conditions.