Made in USA
SFI-Approved Flexplate GM LT1/LT4
InfoVehicle Info Needed
TCIPART NUMBER: 890-399860

SFI-Approved Flexplate GM LT1/LT4

$58695
ShippingShips on Sep 03, 2026
Lowest PriceLowest Price Guarantee

Chevrolet SFI 29.2 Approved Flexplates
SFI-Approved Flexplate
  • GM LT1/LT4
  • One piece
  • 4140 Forged Steel
  • Hobbed-On Ring Gear
  • TIG-Welded Converter Spacers
  • Weighs 7.6 lbs.
  • Sold Individually

    TCI 399860 Features:

    • A gas-nitriding process provides extra surface hardness and strength
    • E-Coated for corrosion protection
    • Pockets and lightening holes are CNC-milled to reduce rotating mass and weight
    • 12,000+ RPM capability
    • SFI 29.2 Certified

     

    • SFI-Approved Racing Flexplates

      TCI Heavy-Duty Flexplates are .0350 in. thicker than stock plates in order to withstand the stress of high-RPM engines and high-stall torque converters. Chevy 168-tooth plates have dual bolt patterns to accommodate both Powerglide and Turbo-Hydramatic (TH) torque converters. TCI also offers externally-balanced Small Block Ford to GM Transmission Adapter Flexplates that feature a built-in pilot adapter and a dual bolt pattern for a simple bolt-on installation. Note: For use with a racing converter or GM Powerglide adapter.

      Show More

      When your build demands strength, durability, and reliable performance under fire, the TCI Heavy-Duty Flexplates deliver exactly that. These heavy-duty components are built to last, especially for high-stall torque converters and high-RPM engines.

      TCI flexplate models are thicker than stock—specifically .0350 inches extra—to resist warping, cracking, or damaging deflection when torque and revs rise. Chevy 168-tooth plates in this line feature dual bolt patterns so they work with both Powerglide and Turbo-Hydramatic transmissions. These plates are precision engineered to maintain alignment, retain structural integrity, and handle the stresses OEM parts can’t reliably overcome.

      If you’re running an LS swap or high output small block, a TCI LS1 Flexplate option gives you a bolt-on upgrade with improved durability, especially if you’ve upgraded torque converter size, stall speed, or intend to push rev limits. Compatibility across various bolt patterns, balanced designs, and high-quality materials mean you can upgrade without compromising fitment or strength.

      A chevy flex plate from this line isn’t just about brute force—it’s about maintaining reliability under load. Proper flexplate selection protects your torque converter, starter, crank flange, and ultimately your transmission. Whether for racing, high performance street, or demanding duty, using a heavy-duty version pays in longer life, fewer failures, and cleaner engagement. Add a Heavy-Duty Flexplate to your setup to get the peace of mind and performance your drivetrain deserves.

    Part TypeFlexplate
    Product LineTCI Heavy-Duty Flexplates
    BrandTCI
    Package Height1.5
    Package Width15.0
    Package Length15.0
    Weight8.4 PG
    Part CategoryPerformance Parts
    Flexplate Material4140 Forged Steel
    QuantitySold individually
    Part FitmentSemi Universal
    Safety RatingSFI 29.2
    FinishE-Coat
    Vendor Part Number399860
    Package Qty1
    Package TypeEA
    No Questions
    No Reviews

    Items You Need

    Quick Shift Automatic Transmission Fluid [1-quart]

    JEGS

    Quick Shift Automatic Transmission Fluid [1-quart]

    Part Number : 555-28070
    $1099$12.99
    You Save$2.00
    Flexible Braided Transmission Dipstick for TH350/TH400 [Black]

    JEGS

    Flexible Braided Transmission Dipstick for TH350/TH400 [Black]

    Part Number : 555-61690
    $9499$111.99
    You Save$17.00
    Flexible Braided Transmission Dipstick for TH350/TH400 [Polished]

    JEGS

    Flexible Braided Transmission Dipstick for TH350/TH400 [Polished]

    Part Number : 555-61590
    $6299$64.99
    You Save$2.00
    Aluminum Transmission Inspection Plate for TH-350 and TH-400

    JEGS

    Aluminum Transmission Inspection Plate for TH-350 and TH-400

    Part Number : 555-60184
    $5399$58.99
    You Save$5.00
    Transmission Intermediate Sprag for 1964-1972 GM TH-400

    JEGS

    Transmission Intermediate Sprag for 1964-1972 GM TH-400

    Part Number : 555-62052
    $11799$127.99
    You Save$10.00
    Governor Recalibration Kit for GM TH-250, TH-350, TH-400, 700R4

    JEGS

    Governor Recalibration Kit for GM TH-250, TH-350, TH-400, 700R4

    Part Number : 555-62070
    $9399$100.99
    You Save$7.00
    Transmission Vacuum Modulator for GM 1963-1990 TH350/TH400 [Adjustable]

    JEGS

    Transmission Vacuum Modulator for GM 1963-1990 TH350/TH400 [Adjustable]

    Part Number : 555-62068
    $2199$23.69
    You Save$1.70
    Transmission Slip Yoke Forged Steel [GM 32-Spline]

    JEGS

    Transmission Slip Yoke Forged Steel [GM 32-Spline]

    Part Number : 555-60671
    $18299$197.99
    You Save$15.00
    Aluminum Transmission Pan for GM TH400

    JEGS

    Aluminum Transmission Pan for GM TH400

    Part Number : 555-61181
    $9699$104.69
    You Save$7.70
    Automatic Transmission Bushings Kit for 1966-1991 GM TH400

    JEGS

    Automatic Transmission Bushings Kit for 1966-1991 GM TH400

    Part Number : 555-62062
    $5099$56.99
    You Save$6.00
    Front Pump Seal Kit for 1965-1998 TH400

    JEGS

    Front Pump Seal Kit for 1965-1998 TH400

    Part Number : 555-60313
    $5399
    High-Volume Front Pump for GM TH400 [6 and 8 Bolt Cases]

    JEGS

    High-Volume Front Pump for GM TH400 [6 and 8 Bolt Cases]

    Part Number : 555-60314
    $48299$521.59
    You Save$38.60
    SFI 4.1 Certified GM TH400 Transmission Case

    JEGS

    SFI 4.1 Certified GM TH400 Transmission Case

    Part Number : 555-60333
    $1,62999$1792.99
    You Save$163.00
    Shift Improver Kit for 1965-later GM TH400

    JEGS

    Shift Improver Kit for 1965-later GM TH400

    Part Number : 555-62148
    $5354$57.99
    You Save$4.45
    Trans-Brake Valve Body Kit for GM TH400 [Billet Aluminum]

    JEGS

    Trans-Brake Valve Body Kit for GM TH400 [Billet Aluminum]

    Part Number : 555-603206
    $53599$578.89
    You Save$42.90
    Transmission Filter and Gasket Kit for TH400 Chevy, BOP

    JEGS

    Transmission Filter and Gasket Kit for TH400 Chevy, BOP

    Part Number : 555-60901
    $1399$15.09
    You Save$1.10
    TH400 Transmission Pan Gasket

    JEGS

    TH400 Transmission Pan Gasket

    Part Number : 555-60982
    $2728$28.99
    You Save$1.71
    Cast Aluminum Transmission Pan for TH400 Automatic Transmission [3 1/2 in. Deep]

    JEGS

    Cast Aluminum Transmission Pan for TH400 Automatic Transmission [3 1/2 in. Deep]

    Part Number : 555-60179
    $16379$177.99
    You Save$14.20
    Flywheel and Flexplate Turning Tool

    JEGS

    Flywheel and Flexplate Turning Tool

    Part Number : 555-60129
    $1499$16.99
    You Save$2.00
    Some parts are not legal for use in California or other states with similar laws / regulations
    p65 warning
    Your Cart

    Your shopping cart is empty!