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 Bearing, Release, Austin Healey Sprite 1.3 Ltr Sprite (Mk IV), 1/66-12/71 1966-1971, Each

PHC Clutch Bearing, Release, Austin Healey Sprite 1.3 Ltr Sprite (Mk IV), 1/66-12/71 1966-1971, Each

$131.33

Sonnax Smart-Tech® Big Input Shaft Kit, Chrysler, Chrysler 47RE, 47RH, 48Re, Each

Sonnax Smart-Tech® Big Input Shaft Kit, Chrysler, Chrysler 47RE, 47RH, 48Re, Each

$3,201.75

TCI Frictions High Perf. Direct TH350 .098 (5 ea.)

TCI Frictions High Perf. Direct TH350 .098 (5 ea.)

$74.87

Wilwood Bearing Cone, Hub, Outer

Wilwood Bearing Cone, Hub, Outer

$116.19

Sonnax Stator Support Shaft Assembly, GM, 4L60-E '04-Up 298mm Reluctor, Each

Sonnax Stator Support Shaft Assembly, GM, 4L60-E '04-Up 298mm Reluctor, Each

$114.37

Motive Gear Axle Shaft, 1541 Manganese, 8x6.5 in. Bolt Pattern, 32.5 in. Length, 33SPL, For CHEVROLET C20 1981–1987, Each

Motive Gear Axle Shaft, 1541 Manganese, 8x6.5 in. Bolt Pattern, 32.5 in. Length, 33SPL, For CHEVROLET C20 1981–1987, Each

$211.38