6L90 Reaction Shell, new and ready to install. Fits the 6L90. Ships fast from the USA.
Despite the shop title, this listing is not a reaction shell. It is the new Sonnax 6L45-6L90-MINI Shift and TCC Kit, a compact valve body and pressure switch repair package for the GM six-speed family. It is aimed at the 6L90 in Silverado and Sierra 2500HD/3500HD pickups, Express and Savana vans and the supercharged Camaro ZL1 and Corvette Z06/ZR1, and the same kit covers the 6L45, 6L50 and 6L80. Owners land here when the truck flares between gears, slams into lockup, runs hot, or keeps setting solenoid performance and pressure control codes that come back after every clear.
The 6L90 shifts entirely with clutches. The TEHCM, the control module and solenoid body bolted to the valve body, commands line pressure and each clutch apply, and pressure switches built into that module report back that the clutch actually applied. When the aluminum valve body bores wear, oil leaks past the pressure regulator, the actuator feed limit valve and the TCC regulator valve. Sonnax describes the result as pressure loss in the main line, clutch apply control, solenoid feed and lockup control circuits. The MINI kit puts the most needed fixes in one box: a pressure regulator valve, a line pressure booster kit, an actuator feed limit valve kit and a TCC regulator valve kit, all drop-in parts that need no reaming. It adds eight .250 inch checkballs plus two spares and a .125 inch checkball, and five laminate discs, five seals and the installation tools to rebuild the TEHCM pressure switches instead of buying a new module.
Before you open the pan, check the fluid level hot and rule out the cheap causes: a twisted cooler line, a stuck cooler bypass valve or a weak pump all produce similar pressure complaints. Put a gauge on the line pressure tap and compare actual pressure with the commanded value on the scan tool; a big gap with a healthy pump points to valve body leakage. Our 6L90 valve body testing guide walks through that process, and the 6L90 shift solenoid guide helps separate a bad solenoid from a leaking bore. If the clutches are already burnt, the kit alone will not bring them back.
Sonnax lists this kit for the GM 6L45, 6L50, 6L80 and 6L90 and does not split it by model year, so it covers the 6L90 across its full run in heavy-duty trucks, vans and the high-output cars. Valve body castings changed over the years, so compare the valves you remove with the new parts before assembly, or send us your year and VIN and we will confirm. Browse the rest of the hardware on the 6L90 parts page.
| Fits | 6L90 |
| Part type | Reaction Shell |
| Condition | New |
| Brand | Sonnax |
| Ships | From the USA |
| Warranty | 1-year |
No. The item is the Sonnax 6L45-6L90-MINI Shift and TCC Kit, a set of drop-in valve body parts plus a TEHCM pressure switch rebuild kit. It contains no hard geartrain parts.
Sonnax lists the kit for the 6L45, 6L50, 6L80 and 6L90 without a year split. Check the removed valves against the new parts, or send us your year and VIN.
The MINI kit carries the most common pressure regulator, booster, actuator feed limit and TCC regulator repairs plus the pressure switch rebuild parts. The full Zip Kit adds more valves and plugs for a complete valve body overhaul.
Often, yes. It includes five laminate discs, five seals and the installation tools to rebuild the switches. If the module has an electrical fault, a rebuilt switch will not fix that.
Refill with Dexron VI, check the level hot, then reset the transmission adapts with a scan tool and drive the relearn so shift timing matches the repaired valve body.
