The TH350 (Turbo-Hydramatic 350) is one of America's most popular classic automatic transmissions. Found in 1969-1986 Chevy, GMC, Pontiac, and Buick vehicles. Easy to rebuild, well-supported, perfect for restorations and hot rods. Here's the complete guide.
TH350 basics
- 3-speed automatic
- Hydraulic control (no electronics)
- Years: 1969-1986 production
- Torque capacity: ~350 ft-lb stock
- Weight: ~120 lbs
- Length: 21.75"
- Applications: Chevy / GMC trucks, Camaro, Chevelle, Nova, Impala, Caprice, Trans Am, more
Common failures
1. Forward clutch wear
The most common failure point. Forward clutch sees high stress.
Fix: Quality friction pack during rebuild.
2. Direct clutch wear
Secondary high-wear point.
Fix: Quality friction pack.
3. Intermediate sprag failure
Sprag wears under load.
Fix: HD sprag during rebuild.
4. Reverse band wear
Stock band fails in HD use.
Fix: HD reverse band.
5. Modulator failure
Vacuum modulator can fail.
Fix: Cheap replacement ($15-30).
6. Governor weights worn
Affects shift timing.
Fix: Governor rebuild or replacement.
7. Pump bushing wear
Standard high-mile wear.
Fix: Pump bushing replacement.
Build recommendations
Stock daily driver (older Chevy / Camaro)
- Alto Red Eagle master kit
- HD reverse band
- HD intermediate sprag
- Stock-replacement HD torque converter
- Total parts cost: $400-650
- Build cost installed: $1,500-2,500
- Expected life: 100,000+ miles
Hot rod / mild performance (350-400 HP)
- Alto Power Pack master kit
- HD reverse band
- HD intermediate sprag
- Performance valve body (TransGo HD shift kit minimum)
- Performance torque converter (2,200-2,500 stall)
- Total parts cost: $700-1,200
- Build cost installed: $2,500-4,000
- Expected life: 75,000+ miles performance use
Performance / race build (450-600 HP)
- Raybestos Stage-1 master kit
- HD components throughout
- Race valve body
- Race torque converter (2,800-3,500 stall)
- Performance servo and band
- Total parts cost: $1,200-2,500
- Build cost installed: $3,500-6,000
- Expected life: Depends on use
Drag race build (600+ HP)
- Race-spec frictions
- Race servo, band, valve body
- Race torque converter (3,500-4,500 stall)
- Possible trans brake setup
- Total parts cost: $2,500-5,000
- Build cost installed: $6,000-12,000
Brand recommendations
Alto
- Red Eagle and Power Pack frictions
- Quality master kits
- Recommendation: Yes for all builds
Raybestos
- Stage-1 and GPZ
- Recommendation: Yes for performance
Sonnax
- HD valve body upgrades
- Recommendation: Yes for performance rebuilds
TransGo
- HD shift kits for TH350
- Recommendation: Yes for tow/performance
B&M
- Performance valve bodies (TrickShift, etc.)
- Performance torque converters
- Recommendation: Yes for street/strip
Coan Engineering
- Performance and race TH350 builds
- Recommendation: Yes for race
TCI
- Performance valve bodies and torque converters
- Recommendation: Yes for performance
ATI Racing
- Race-grade TH350 builds
- Recommendation: Yes for serious race
TH350 vs TH400 comparison
TH350:
- 3-speed
- Lighter (120 lbs)
- Shorter (21.75")
- Less torque capacity (~350 ft-lb stock)
- Cheaper to rebuild
- Better for small block / daily driver
- Wider availability
TH400:
- 3-speed
- Heavier (135 lbs)
- Longer (24.5")
- More torque capacity (~450 ft-lb stock)
- Race-proven
- Better for big block / HD use
When to choose TH350:
- Small block applications
- Daily driver
- Restoration
- Hot rod with under 400 HP
- Lighter vehicles
- Tight engine bay
When to choose TH400:
- Big block applications
- HD use
- 400+ HP applications
- Race builds
- Heavier vehicles
TH350 swap considerations
Why people swap to TH350:
- Cheap and available
- Easy to rebuild
- Strong aftermarket
- Lighter than TH400
- Shorter package
Common swap applications:
- Older muscle cars getting trans rebuilt
- Drag race builds (sometimes)
- Hot rod / restomod
Swap parts:
- Bellhousing pattern: most Chevy V8s
- Transmission cooler lines
- Driveshaft (length specific)
- Crossmember
- Shifter assembly
Fluid
- Spec: Dexron III originally, Dexron VI (backward compatible) is current
- Capacity: ~12 quarts total, ~5 quarts in pan
- Service: 30K-50K miles depending on use
Cost summary
DIY rebuild:
- Stock: $400-650
- Performance: $700-1,200
- Race: $1,200-2,500
- Drag race: $2,500-5,000
Shop rebuild installed:
- Quality independent: $1,500-2,500
- Performance shop: $3,500-6,000
- Race shop: $6,000-12,000
Reman swap:
- Quality reman: $1,200-2,000 installed
- Built reman from race shop: $2,500-4,500
What we sell
Master rebuild kits for TH350 with Alto and Raybestos frictions, HD bands and sprags, B&M and TCI performance valve bodies, race-spec torque converters, complete shift kits.
Need TH350 parts? Shop our TH350 catalog. Master rebuild kits, performance valve bodies, race torque converters. Free shipping over $70.
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