2015–2019 GMC Sierra: 8-speed transmission shudder (torque converter)
Likely causes, ranked
- Torque converter clutch shudder from original fluid (fluid exchange per GM bulletin)Shop
- Damaged torque converter (replaced)Shop
Real-owner fix counts will appear here as reports come in.
DIY or shop: See DIY or shop section
Parts to check
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Symptom: A shake or shudder at about 25–80 mph under light throttle, like driving over rumble strips.
Likely causes
- The torque converter clutch and the original fluid. GM's bulletin calls for a full fluid exchange with Mobil 1 LV ATF HP. Owners on SilveradoSierra.com report the exchange often cures it.
- A damaged converter. If it keeps shuddering after the exchange, the converter is replaced.
DIY or shop?
Shop. The exchange needs a machine flush to replace enough of the fluid.
Useful steps
- Ask for 18-NA-355 by number.
- Confirm the dealer is using the specified fluid.
- Get it documented while you're still under the powertrain warranty.
Vehicle focus: 2015–2019 GMC Sierra.
Safety / mechanic note
This is more a drivability problem than a safety one, but don't let it turn into converter damage.
Recalls & service bulletins
Technical service bulletins
- 18-NA-355 GM bulletin for 8-speed shudder/shake felt like rumble strips: transmission fluid exchange with Mobil 1 LV ATF HP; converter replacement if damage remains. Details
NHTSA complaints: 227 keyword-matched complaints for GMC Sierra 1500 2015–2019 (of 2,247 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-15).
Always check your VIN for open recalls at nhtsa.gov/recalls.
Sources
What actually fixed it?
Had this problem? Tell other owners what the real fix was. Reports are counted above; we never show made-up numbers.