4L80E Sonnax 34200-52, number 7 Low / Reverse Checkball Seat.
Made from high-strength, wear-resistant aluminum for added durability, this new checkball seat allows you to restore hydraulic control for normal pressure and performance.
Vehicles with GM 4L80E and 4L85E transmissions commonly exhibit wear in the number 7 low/Reverse checkball seat location. This issue is caused by normal movement of the checkball and slight movement of the seat within the bore over time.
As wear progresses, sealing function of the checkball seat becomes compromised and results in loss of rear band apply (RBA) pressure. This can result in a burnt rear band, delayed or no Reverse and loss of engine braking in manual low.
Installing Sonnax number 7 low/Reverse checkball seat 34200-52, restores the hydraulic integrity of this circuit to re-establish normal pressure and performance. The checkball seat is made from high-strength, wear-resistant aluminum for added durability.
- Burnt Reverse band
- Delayed Reverse
- No Reverse
- No engine braking in manual low