Vehicles with GM 4L80-E and 4L85-E transmissions commonly exhibit wear in the #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 #7 Low/Reverse checkball seat 34200-52 restores the hydraulic integrity of this circuit to re-establish normal pressure and performance.

Replaces worn checkball seat to correct loss of RBA apply pressure
Checkball seal made from high-strength, wear-resistant aluminum for added durability
Drop-in Zip Valve™ parts install quickly and easily

Learn More About Zip Valve™ Drop-In Repairs

More From This Category

PHC Clutch Concentric Slave Cylinder, For Holden Vectra 2.0 Ltr, C20SE JR, 1/97-8/98 1997-1998, Each

PHC Clutch Concentric Slave Cylinder, For Holden Vectra 2.0 Ltr, C20SE JR, 1/97-8/98 1997-1998, Each

$197.24

PHC Clutch Bearing, Release, For Ford Escort 1.1 Ltr, KL11L Mk II, 12/74-8/80, New Zealand Model 1974-1980, Each

PHC Clutch Bearing, Release, For Ford Escort 1.1 Ltr, KL11L Mk II, 12/74-8/80, New Zealand Model 1974-1980, Each

$64.64

PHC Clutch Concentric Slave Cylinder, For Ford Mondeo 2.0 Ltr TDCi, 96kw 6 Speed, 6/03-8/07 2003-2007, Each

PHC Clutch Concentric Slave Cylinder, For Ford Mondeo 2.0 Ltr TDCi, 96kw 6 Speed, 6/03-8/07 2003-2007, Each

$202.39

Motive Gear Axle Shaft, 1541 Manganese, 5x5.5 in. Bolt Pattern, 29.625 in. Length, 28SPL, ForD BRONCO 1966–1975, Each

Motive Gear Axle Shaft, 1541 Manganese, 5x5.5 in. Bolt Pattern, 29.625 in. Length, 28SPL, ForD BRONCO 1966–1975, Each

$291.64

RTS OE Transmission Overhaul Kit C6, Ford Falcon, Mustang, Gaskets, Seal Kit

RTS OE Transmission Overhaul Kit C6, Ford Falcon, Mustang, Gaskets, Seal Kit

$103.95