TH350 TRANSMISSION INFO AND OVERVIEW

Introduced in 1969 to replace the aging 2-speed Powerglide, the Turbo-Hydramatic 350 (TH350) is GM’s legendary lightweight, compact, and incredibly durable 3-speed automatic. While it lacks an overdrive gear, its low parasitic power loss, smaller physical footprint, and natural baseline strength make it a long-standing favorite for classic muscle cars, drag racing, hot rods, and early C10 builds. Unlike modern electronic transmissions, the TH350 is entirely mechanically and hydraulically controlled, making it a simple but brutally effective transmission when upgraded properly.

COMMON FAILURE POINTS (STOCK):

  • Intermediate Sprag Outer Race (Notorious for cracking or shattering during hard 1-2 shifts)

  • Direct Clutch Pack (Prone to burning up under high horsepower and RPMs)

  • Case Lugs (Center support fretting and chewing into the aluminum case)

  • Sluggish Factory Shifts (Soft shifts leading to premature band and clutch wear)

PERFORMANCE SOLUTIONS: Through years of building these iconic units, we've engineered specific build stages that address their few factory weaknesses, transforming them from reliable daily drivers into bulletproof street and strip transmissions.

KEY IMPROVEMENTS:

  • Hardened intermediate sprag races to completely eliminate 1-2 shift explosion

  • Machined clutch pistons and high-energy frictions to increase direct clutch holding capacity

  • Case-saver anti-fret plates to protect case lugs from tearing out under heavy torque

  • Recalibrated valve bodies and shift kits for lightning-fast, authoritative shifts

Schedule Diagnosis (Please Plan to leave Vehicle)

Turbo 350 Automatic Transmission Rebuild (TH350)

  • th350-transmission-rebuild-package-chevy-gm-automatic-transmission-service

    Turn-Key Re-builds | TH350 $2,950+ Starting Price | 12-24 Month Warranty

    The Flagship TH350 Performance Package Built to handle aggressive street driving and weekend strip duty without breaking a sweat. This comprehensive, turn-key service includes professional removal, custom rebuilding, complete vehicle integration, and rigorous diagnostic testing.

    Inside the Build:

    • Hardened Intermediate Sprag Race: Replaces the brittle factory race to withstand violent 1-2 upshifts and hard acceleration without shattering.

    • High-Capacity Direct Clutches: Upgraded with high-energy frictions (like Raybestos or Alto Red Eagle) and modified to hold additional plates, eliminating high-RPM slip.

    • Upgraded Valve Body & Shift Kit: Custom recalibrated to cure the factory "mushy" feel, delivering much firmer, faster shifts that keep the engine in its powerband.

    • Performance Converter: Heavy-duty torque converter, custom-stalled to match your specific engine, camshaft profile, and rear gear ratio.

    The Service Package Includes: Professional removal and installation. Premium synthetic fluid and all necessary build components. 12,000-mile check-up and pan inspection.

    Don't settle for a basic, soft-shifting factory rebuild. Our flagship TH350 Performance Package is built to take a beating. We gut the notorious factory weak points and upgrade your unit with a hardened sprag race, high-capacity direct clutches, and aggressive hydraulic modifications. This is a complete, turn-key package: we handle the professional removal, custom bench build, heavy-duty torque converter pairing, and installation using premium fluids. After thorough road testing and vacuum modulator tuning, you get a 12,000-mile pan inspection and our full 24-month/24,000-mile warranty covering all parts, fluids, and labor. Built for power, backed for peace of mind.

    Payment Notice: A 3.5% convenience fee is applied to all credit card transactions.

    TURN-KEY INSTALLATION & INTEGRATION

    Your final installation invoice will reflect the following additions where applicable: Custom Converter, High-Performance Upgrades, Premium Fluids, and applicable NC Taxes.

    AVAILABLE BUILD UPGRADES

    • OEM-Spec Torque Converter: Reliable, factory-level power transfer for mild cruisers.

    • Heavy-Duty Sprag Upgrade (36-Element): An extreme-duty mechanical diode or 36-element sprag drum conversion for high-horsepower drag cars.

    • Stage 3 Performance Package: Includes Hardened Sprag Race, upgraded direct clutches, case-saver ring, and a full Street/Strip shift kit.

    • Stage 4 Smart-Tech Package: Includes Billet Input Shaft, Billet Forward Drum, manual valve body, and deep aluminum pan for dedicated track use.

    • Full Manual Valve Body Conversion: Eliminates automatic shifting entirely for drag racing applications (Quote Required).

    PLATFORM COMPATIBILITY

    • Chevrolet: C10/K10 Trucks, 1st & 2nd Gen Camaro, Chevelle, Nova, C3 Corvette, Impala

    • GMC: C/K series trucks, early Jimmy

    • Pontiac: Firebird, GTO, LeMans, Tempest

    • Custom Applications: The ultimate compact 3-speed choice for hot rods, street rods, and drag cars with limited transmission tunnel space.

    SHOP TECHNICAL NOTE: Unlike the 700R4, which relies entirely on a highly sensitive TV cable for internal line pressure, the TH350 uses engine vacuum via a Vacuum Modulator to control shift timing/firmness, and a separate Kickdown Cable (Detent Cable) purely for wide-open-throttle downshifts.

    Call 704-933-9727 to get a custom quote!