Popular Performance Parts

TH400 Reverse Cushion Kit (1965-1992) TransGo

TH400 Reverse Cushion KitFits all 400 1965-onDoes not fit 4L80E Corrects/Prevents/Reduces: Harsh reverse engagement Transmission removal is not required for this upgrade!

TH400 Transmission Stick Shift Reprogramming Kit (1965-1992) TransGo

Turbo 400 Transmission Reprogramming Kit™with Manual Shift ControlFits all 400 1965-on Features: Stick Shift, full manual control Full race; competition, off road and pro-street Converts back to automatic from the outside in 5 minutes Also...

TH400 Transmission Reprogramming Kit - TransGo

Features Automatic shift Street or full race Holds 1st and 2nd to any RPM Back-shifts to 2nd and 1st at any RPM Tow&Go™ or competition Also Includes (2) different size 1-2 shift valves Direct clutch high rate return springs Heavy duty...

TH400 Transmission Reprogramming Pro-Race Kit - TransGo

Features Automatic shift Street or full-race Holds 1st and 2nd to any RPM Back-shifts to 2nd and 1st at any RPM Tow&Go™, competition, pro-race, heavy duty, show-off Awesome capacity with adjustable shift timing and feel Also Includes (2)...

TH400 Line Pressure Booster Kit

TH400 Line Pressure Booster KitPart No. 400-LB1 Sonnax hydraulic line pressure booster kits contain stronger pressure regulator springs and large ratio boost valves designed to work together to provide progressive pressure increases as driving...

TH400 Boost Valve Kit (No O-Rings Style) Sonnax

TH400 Boost Valve KitPart No. 34910-05K Factory Style, No O-Rings Vehicles with a THM 400 transmission frequently have poor line rise, soft 1-2 and/or 2-3 shifts,and/or Reverse engagement difficulties. These problems can be caused by the...

TH400 Boost Valve Kit (O-ring Style) Sonnax

TH400, TH425 Boost Valve KitPart No. 34910-01K O-Ring Style Vehicles with a GM 400 and 425 transmissions frequently have poor line rise, soft 1-2 and/or 2-3 shifts and/or Reverse engagement difficulties. These problems can be caused by the...

4L80E TH400 Heavy Duty Forward Clutch Hub

Sonnax heavy duty forward clutch hub 34322-01 is an ideal upgrade over OE hubs in GM 400, 425, 4L80-E and 4L85-E applications. It is made from 1045 steel forging and features a thicker cross-section for increased strength. Made from forged 1045...

4L80E TH400 HD Forward Clutch Hub Front Washer (Pack of 5) 0.078"

Pack of 5 Sonnax forward clutch hub front washer 34298-078 replaces the OE .063" thick washer between the forward clutch hub and the forward drum. It is .015" thicker than OE and is the optimal way to tighten front unit endplay in most common builds...

4L80E TH400 Extreme Duty Forward Clutch Hub Kit

Sonnax extreme duty forward clutch hub kit 34322-02K is manufactured from forged 4140 steel and features nitrited and case-hardened splines to eliminate spline wear in extreme applications. Includes bearing between hub and direct clutch housing. The...

TH350 TH400 Powerglide HD Pump Bushing (Steel - 0.615'')

Worn babbit pump bushings in GM Powerglide, 350, 400 and Allison®AT540 units allow the converter hub and inner pump gear to move off-center, causing damage to the pump gears and pump housing crescent. Sonnax pump bushing 34034T-01 is a direct...