TH350 vs TH400 Transmissions: Key Differences Explained
Bottom line: The TH350 is a 3‑speed, lighter, and cheaper unit best for street‑driven cars, while the TH400 is a beefier 4‑speed built for heavy trucks and high‑torque applications.
TH350 vs TH400 Transmissions: Key Differences Explained
Image: TH350 vs TH400 Transmissions: Key Differences Explained – Performance Comparison and Specifications
Design & Looks
Both gearboxes share a similar cast‑iron case, but the TH400’s case is noticeably larger and heavier. The extra bulk allows it to handle more torque, which is why you’ll see it in bigger V8 engines and full‑size pickups. The TH350, on the other hand, was designed to be compact enough for midsize coupes and muscle cars of the 1960s.
- TH350: 3 forward gears, 0.70‑to‑2.79 first‑gear ratios, weighs about 140 lb.
- TH400: 4 forward gears, 0.71‑to‑2.66 first‑gear ratios, weighs roughly 190 lb.
Performance & Mileage
Because the TH350 is lighter, it generally improves fuel economy by a few tenths of a mile per gallon compared to the TH400. However, the extra gear in the TH400 lets the engine stay in its sweet spot more often, which can boost real‑world performance on the highway.
Torque capacity is the biggest practical difference. The TH350 comfortably handles up to 300 lb‑ft, while the TH400 can manage around 380 lb‑ft. If you plan to run a high‑output V8 or add a supercharger, the TH400 is the safer choice.
Price & Rivals
On the used market, a TH350 typically sells for $200‑$400, whereas a TH400 commands $300‑$600 due to its heavier construction and broader application range. Both compete with the later Chevrolet 4L60‑type automatics, but the TH series remains popular among classic‑car enthusiasts because of their simplicity and durability.
- TH350 – cheaper, easier to rebuild, perfect for classic muscle builds.
- TH400 – more robust, better for trucks and high‑torque builds, slightly higher price.
| Transmission | Engine Compatibility | Typical Mileage Impact | Typical Used Price (USD) | Top Features |
|---|---|---|---|---|
| TH350 | Small‑to‑mid V8s, 5.0‑6.5 L | +0.2‑0.4 mpg vs TH400 | $200‑$400 | Lightweight, 3‑speed, easy rebuild |
| TH400 | Large V8s, 6.5‑7.5 L, trucks | -0.1‑0.2 mpg vs TH350 | $300‑$600 | 4‑speed, higher torque capacity, stronger case |
FAQ
- What is the main advantage of the TH350? Its lighter weight and lower cost make it ideal for classic muscle cars that don’t need extreme torque handling.
- Can the TH400 be used in a daily driver? Yes, but expect a slight drop in fuel economy compared to the TH350; the extra gear can smooth out highway cruising.
- Which transmission lasts longer? Both are robust if maintained, but the TH400’s heavier case gives it an edge in high‑torque, high‑stress situations.
If you’ve swapped one of these gearboxes before, share your experience in the comments below!
Source: Read Official News
