The Turbo Hydra-Matic 400 is the bulletproof 3-speed automatic of the muscle car era. 450+ ft-lbs stock capacity. Loved by drag racers and restoration shops. The rebuild is more straightforward than a 4L60E and the parts catalog is still mature.
Years
1964-1990
Maker
GM
Ship Time
Same-day before 2pm ET
Common TH400 Failures
| Symptom | Most Likely Fix |
|---|---|
| Slip in 1st or 2nd | forward or intermediate clutch pack |
| No 3rd gear | direct clutch pack |
| Pump leak | pump seal + bushing |
| Reverse engages with thump | reverse clutch pack |
| No band apply | 2nd gear band adjustment or replacement |
TH400 rebuilds run $1,200-$2,000 retail in restoration shops. Drag-racing builds (HD planet, manual valve body) go $3,000+. Classic-car owners pay for it done right.