Drop-in 2-3 shift valve for GM 4L60E, 4L65E and 4L70E that keeps the overrun clutch applied in 1st, 2nd and 3rd for engine braking and sprag protection.
On a stock GM 4L60E, 4L65E or 4L70E the 2-3 shift valve only applies the overrun clutch in D3 third gear. That leaves the input sprag and forward clutch carrying the load in the lower gears with no overrun element backing them up, which is where these units tend to come apart in trucks that tow, plow rigs and built performance cars. This Sonnax drop-in valve changes that: it applies the overrun clutch in D3 first, second and third, so the sprag and forward clutch get help across the whole range instead of just top gear.
The practical payoff is engine braking and durability. With the overrun clutch on, you get real downshift engine braking in second while the shifter stays in the D3 position, which is exactly what you want on grades and behind a load. It also plays well with aftermarket electronic paddle-shifter setups that command manual downshifts, since the valve keeps the overrun element applied when the trans is electrically downshifted.
Installation is a true drop-in. It swaps directly into the factory 2-3 shift valve bore in the valve body with no reaming, no machining and no separator-plate changes. Pull the valve body, remove the OE valve from its bore, slide the Sonnax valve in with the return spring, and reinstall. If you are already in the valve body for a shift kit or a rebuild, this is a five-minute add that pays for itself in sprag life.
| Fits | GM 4L60E, 4L65E, 4L70E automatic transmissions |
| Function | 2-3 shift valve that applies the overrun clutch in D3 1st, 2nd and 3rd (stock applies it only in D3 3rd) |
| Benefit | Adds engine braking in 2nd and protects the input sprag and forward clutch |
| Best for | Tow rigs, plow trucks, high-performance builds and units with aftermarket electronic paddle shifters |
| Installation | Drop-in replacement into the factory shift valve bore; no reaming or machining |
| Ships from | USA |
