Kia Stinger: 8-speed A8TR1 auto harsh downshift on deceleration

The A8TR1 8-speed automatic transmission calibrated for the Stinger CK exhibits harsh and clunky downshifts during trail-braking or engine-braking deceleration, particularly in Normal and Sport drive modes. The issue originates from TCU software that applies clutch packs too aggressively during downshift sequences at low throttle. Drivers report a noticeable jolt between 3rd-2nd and 4th-3rd gear transitions when slowing. Kia released multiple TCU calibration updates through the dealer network to address the complaint, but vehicles not presenting for scheduled dealer visits may remain on outdated software. Transmission fluid degradation beyond service interval accelerates the symptom onset.

• Clunk or jolt felt through the driveline during deceleration as the transmission downshifts
• Hesitation followed by an abrupt gear change when slowing without heavy braking
• Symptom worsens when transmission fluid is overdue for replacement
• More pronounced in cold ambient temperatures before the transmission reaches operating temperature
• Occasional shudder in Sport mode between 3rd and 2nd gear at around 40 km/h

1. 1

   Test drive on a road allowing deceleration from 80 km/h to 30 km/h without braking — assess for a jolt through the driveline.

2. 2

   Check transmission fluid colour via service records; it should be replaced by 60,000 km.

3. 3

   Ask the dealer to confirm TCU software version is current per Kia service campaign.

4. 4

   If a workshop inspection is possible: Inspect via OBD-II scan for any stored transmission fault codes related to clutch slip or pressure control.

Parts involved: Clutch.

$300 to $3,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Has the transmission software ever been updated at a Kia dealer?”
• “Has the transmission fluid been changed and if so when?”
• “Have you noticed any clunking or jolting when slowing down in traffic?”
• “Has the car been used regularly in Sport or Sport+ drive modes?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.