When the GM 4L60-E family of transmissions evolved from the 700-R4, the overrun clutch is no longer applied in 1st and 2nd when accelerating from a stop in D3 shifter position. This change was made to improve coastdown drivability in D3 but had the side effect of reducing the torque capacity of the input section.
For greatly improved input sprag and Forward clutch durability, Sonnax drop-in, heavy duty 2-3 shift valve 77754-41 for 4L60-E, 4L65-E and 4L70-E units will apply the overrun clutch in D3 1st, 2nd and 3rd Gears.
Improves input sprag and Forward clutch durability
Critical upgrade for all heavy-duty and performance vehicles
Drop-in Zip Valve parts install quickly and easily
Range
Gear
Overrun with OE 2-3 Valve
Overrun with Sonnax 77754-41 Valve
OD
1st
OFF
OFF
2nd
OFF
OFF
3rd
OFF
OFF
4th
OFF
OFF
D3
1st
OFF
APPLIED
2nd
OFF
APPLIED
3rd
APPLIED
APPLIED
D2
1st
APPLIED
APPLIED
2nd
APPLIED
APPLIED
D1
1st
APPLIED
APPLIED
2nd
APPLIED
APPLIED
Learn More About Zip Valve Drop-In Repairs
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