8L90 Shift Kit 2015, new and ready to install. Fits the 8L90. Ships fast from the USA.
If your 2015-or-newer Silverado or Sierra 1500 with the 5.3L or 6.2L, a Tahoe, Yukon or Escalade, a C7 Corvette or a V8 Camaro is banging into gear, running hot under tow, or setting a converter clutch code, the problem very often lives in the valve body rather than the hard parts. This is the TransGo SK 8L90 SHIFT KIT valve body repair kit, built for the GM 8L90 from the 2015 model year on. It is a repair kit, not a bolt-on: it goes into your existing valve body during a valve body service or a full rebuild and replaces the valves that wear and cause the classic 8L90 complaints.
The 8L90 is an electronically controlled eight-speed. The TCM commands seven variable force solenoids, but the solenoids only send a signal. The regulator valves in the lower and control valve bodies turn that signal into actual clutch, line and converter pressure. In a high-torque V8 truck those valves work hard, and as their aluminum bores wear the pressure they produce drifts away from what the computer asked for. Sonnax has documented field units running line pressure well above the roughly 315 psi design peak because of a worn pressure regulator lineup. High line feels like harsh, banging shifts; low line from worn regulators shows up as soft, slipping shifts that cook clutches.
The TransGo kit addresses those circuits directly. Per TransGo, it includes a drop-in pressure regulator and shuttle valve line-up, a drop-in TCC regulator valve, drop-in S2, S3 and S4 regulator valves, an oversize converter feed limit valve and an oversize AFL valve. Restoring those valves restores the pressures the TCM is calibrated for, so the shift adapts can do their job again.
Check the fluid first. A large share of 8L90 shudder complaints trace to moisture-contaminated original fluid, and GM's fix is a fluid exchange to the current DEXRON HP fluid, laid out in our 8L90 / 8L45 shudder and harsh shift guide. If the fluid is correct and the complaint stays, put a gauge on the line pressure tap and compare actual to commanded pressure on a scan tool. Line that tracks far above command points at the pressure regulator bore this kit corrects. Our 8L90 valve body symptoms and testing guide walks through the bore-by-bore tests. Note that this kit does not replace the signal accumulator pistons in the control solenoid valve body, which are a separate wear point at S3 and S4.
TransGo lists the SK 8L90 for all 2015-on 8L90 and 8L45 units, so this listing covers the 2015 model year and every 8L90 year after it. That includes Silverado and Sierra 1500, Tahoe, Yukon, Suburban, Escalade, Corvette, Camaro and the Express and Savana vans that use the 8L90. GM made running changes over the years, including a redesigned S4 control valve for 2019, so tell us your year and VIN before ordering if your unit has been updated or rebuilt. All of our other 8L90 parts are on the 8L90 transmission parts page.
| Fits | 8L90 2015 |
| Part type | Shift Kit |
| Condition | New |
| Brand | TransGo |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes. TransGo lists the SK 8L90 for all 2015-on 8L90 and 8L45 transmissions, and the 2015 model year is the first year of the 8L90. If the transmission has been replaced or rebuilt, send us the year and VIN so we can confirm what is in the truck.
It can if the shudder comes from worn TCC regulator or converter feed circuits, which the kit corrects. If the cause is contaminated fluid, the GM fluid exchange to DEXRON HP comes first, and if the converter clutch itself is worn out the converter has to be replaced.
TransGo states the kit requires its AFL-G2-TK tool kit. You also need a scan tool that can run the GM Transmission Service Fast Learn after the valve body goes back in.
DEXRON HP only, which is Mobil 1 Synthetic LV ATF HP. Do not use DEXRON VI or DEXRON ULV. Set the level with the engine running and the fluid in the hot-check window at the pan plug.
The goal of this kit is correct pressure, not a race-car shift. A worn 8L90 often shifts harshly because line is too high, so restoring the regulator lineup typically makes it firmer where it was slipping and smoother where it was banging, once the adapts are relearned.
