GM 6T30 6-Speed FWD Automatic · GM/Chevrolet/GMC/Cadillac/Buick · Expert rebuild service since 1987. Lifetime warranty. Free diagnostic.
2010–2019 Chevrolet Sonic, Spark; 2010–2016 Chevrolet Cruze (1.4T/1.8L); lightest-duty GM FWD 6-speed transaxle
| Configuration | 6-speed FWD transaxle — smallest of the 6T family |
|---|---|
| Gear Ratios | 1st 4.48:1 · 2nd 2.87:1 · 3rd 1.84:1 · 4th 1.41:1 · 5th 1.00:1 · 6th 0.74:1 · Rev 3.82:1 |
| Fluid Type | Dexron VI ATF |
| Fluid Capacity | 7.0 qts total, 3.5 qts service refill |
The 6T-family SRV bore is a family-wide known weakness. Wear allows fluid to bypass the servo, causing 2nd-gear slip that no adjustment can fix.
Symptoms: Slipping in 2nd gear; harsh 1-2 upshift; shift quality degrades over time
Small-displacement applications still wear the solenoid body at 80k–100k miles.
Symptoms: Erratic shifts; limp mode; P0750-series codes
TCC shudder is common in high-mileage 6T30 units in city driving applications.
Symptoms: Shudder at 30–45 mph under light throttle
Full disassembly. SRV bore measured — Sonnax oversized servo installed if worn. Solenoid body replaced. TCC inspected. All clutch packs replaced. Full soft parts kit.
Dexron VI every 40,000 miles. The 6T30 is a small unit in a small car — maintain fluid quality and it's reliable.
The Servo Release Valve (SRV) bore controls 2nd-gear band release timing. When it wears oval, fluid bypasses and causes a harsh 1-2 shift and 2nd-gear slip. Sonnax makes an oversized bore kit that restores it without case replacement.
Very likely. SRV bore wear is the most common 6T-family failure. We measure the bore before recommending a repair — if worn, the Sonnax kit fixes it.
2 days.
Dexron VI ATF.
$1,400–2,000.
Free diagnostic, written estimate, lifetime warranty. Chicago's 6T30 rebuild specialists since 1987.
