The most commonly reported 8L90 problems are a shudder or vibration at steady cruising speeds, usually traced to the torque converter clutch, harsh or clunky shifts, especially at low speed, and delayed or erratic engagement. GM has issued service bulletins for the shudder that call for exchanging the transmission fluid for an updated GM-specified fluid, and software updates for some shift-quality complaints. Fluid condition and level matter a great deal with this transmission.
What is the 8L90?
The 8L90 is GM’s heavy-duty eight-speed automatic, introduced for the 2015 model year. It has been used in the Corvette, the Camaro SS and ZL1, 6.2-liter Silverado and Sierra 1500 pickups, the Escalade and other GM trucks and SUVs. Confirm what your vehicle has from the RPO codes on the service parts label; what transmission do I have? explains how.
Common 8L90 problems
Shudder or vibration
Owners describe a vibration like driving over rumble strips, typically at light throttle and steady speed. It is most often caused by the torque converter clutch slipping and grabbing as it locks up, which is related to the fluid’s friction properties. GM service bulletins address it with a fluid exchange using an updated fluid. If the shudder persists after the correct fluid service, the torque converter may need replacing. See torque converter shudder for how to tell converter shudder from engine misfires and driveline vibration.
Harsh, clunky or delayed shifts
Hard 1-2 or 2-3 upshifts, clunky downshifts when coming to a stop and delayed engagement into drive or reverse are frequent complaints. Some are improved by software updates and by the transmission relearning its shift adapts; others come from low or degraded fluid, valve body wear or internal damage.
Slipping and overheating
Flaring between gears or engine speed rising without acceleration means the clutches are slipping, which is serious; see transmission slipping: signs and causes. Heavy towing raises fluid temperatures; transmission fluid temperature covers safe ranges.
How to prevent 8L90 problems
- Use only the fluid GM specifies for your transmission, and keep the level correct.
- Change the fluid more often if you tow or drive in heavy traffic; see how often to change transmission fluid.
- Check the transmission fluid color and smell when you service the vehicle.
- Ask a dealer whether any service bulletins or software updates apply to your vehicle.
Repair or replace?
Fluid service and software updates are the first steps for shudder and shift complaints. Slipping, metal in the fluid or a failed converter that has contaminated the transmission usually point to a rebuild or replacement. We carry two 8L90 transmissions, each supplied with a torque converter: the RoadReady 8L90 for $4,399.00, a direct replacement, and the StreetMonster 8L90E for $3,999.00, an upgraded unit for daily driving, towing and moderately modified engines. Compare them on our 8L90 transmissions page and confirm fitment with your VIN before ordering.
More guides: 10R80 problems · 6L80 vs 6L90 · 10L80 problems · checking fluid without a dipstick · 6L80 vs 8L90 · 8L90 vs 10L80 · how long an 8L90 lasts.
Shipping is a flat $80.00 per order to US addresses, with 15-day free returns. Questions? Ask a parts specialist.