- Broken clutch piston
- Broken servo
- Damaged case
- High line pressure
Unregulated EPC pressure forces pressure regulator into high line position.
This self-regulating reverse boost valve regulates EPC pressure to 95-105 psi with an encapsulated relief valve.
Boost Valve Kit
- O-Rings (2)
With built-in relief
Common problems in vehicles with a 4L80-E transmission include uncontrollable line rise (upward of 500 psi), high line pressure in reverse, broken direct clutch drums and/or broken cases. These problems can be caused by excessive EPC torque signal pressure. The Sonnax self-regulating reverse boost valve 34200-10K eliminates these problems by limiting EPC pressure.
- Hardened steel boost valve has an encapsulated relief valve that will allow EPC pressure to exhaust if it exceeds 95-105 psi.
- Boost valve with over 20% wider spools to provide better durability and increased sealing contact area.
- Boost valve spools have annular grooves to reduce side loading that causes wear.
- Closely toleranced sleeve restores the hydraulic integrity between the valve and sleeve.
- O-rings have been added to the sleeve to provide a positive seal that compensates for pump bore wear.
Kit includes instructions to retrofit parts dating back to 89.
- Patent No. 6,776,736