Sonnax GM TH400 Transmission

Internal

Bearing Kit SBK-G10

Helps cure:

Bearing noise
Bearing failure

Clutch Volume Spacer Kit 34554-11K

For use with heavy duty forward drum 34554-01.

Direct Drum Sleeve Kit 34838-01K

In 4L80-E units, part can be used in either early or late-model drums.

Helps cure:

Direct clutch failure
Delayed 3rd
Delayed Reverse
Code 87, 730, 756, 1811
No 3rd
No Reverse
Maximum line presssure
No 4th
2nd Gear starts w/MIL on
TCC slip codes

Extreme Duty Forward Clutch Hub Kit 34322-02K

Extreme Duty Input Shaft 27280-02

For use with pumps converted for a 27-spline, 1-3/16" shaft configuration.

Shaft Material: 300M
Front Spline Tooth Count: 27
Journal Dia.: 1.188"

Extreme Duty Input Shaft 35280-02

For use with turbine support bushing in converter.

Shaft Material: 300M
Shaft Dia.: 1.125"
Front Spline Tooth Count: 35

Extreme Duty Main Shaft 34672-05

Material: Aermet

Forward & Direct Clutch Inner Snap Ring 34577-01

Fits AT-540/543/545.

Helps cure:

Lost or damaged component

Forward Clutch Hub Front Washer 34298-078

Forward Hub

Material: Steel
Thickness: 0.078"
Outer Dia.: 1.781"
Inner Dia.: 1.289"

Helps cure:

Excess front endplay

Forward Clutch Hub Washer (Rear) 34301-078

Forward Clutch Drum

Material: Steel
Thickness: 0.078"
Outer Dia.: 1.780"
Inner Dia.: 1.405"

Helps cure:

Excess front endplay
Forward clutch & sealing ring failure
Reduced bearing, thrust washer & sealing ring life

Forward Clutch Hub Washer (Rear) 34301-094

Forward Clutch Drum

Material: Steel
Thickness: 0.094"
Outer Dia.: 1.780"
Inner Dia.: 1.405"

Helps cure:

Excess front endplay
Forward clutch & sealing ring failure
Reduced bearing, thrust washer & sealing ring life

Front/Rear Unit Endplay Shim 34500-Z

Updated 3-tang style shim fits all units, including '97-later 4L80-E and 4L85-E units.

Material: Steel
Tang Count: 3
Inner Dia.: 1.165"
Thickness: 0.010"
Outer Dia.: 1.940"

Helps cure:

Excess front endplay
Excess rear endplay
Burnt Forward clutch
Premature seal ring failure

Governor 400

2nd Design Only

Helps cure:

Shift concerns

Governor Gear Kit 402

Color: White

Helps cure:

Shift concerns

Heavy Duty Clutch Retaining Ring 28124

Intermediate clutch backing plate Upgrade for Intermediate clutch retaining ring.

Heavy Duty Forward Clutch Hub 34322-01

Heavy Duty Forward Drum 34554-01

Heavy Duty Forward/Direct Spring Retainer 34554-12

Heavy Duty Input Shaft 30280-02

For use with turbine support bushing in converter.

Shaft Material: 300M
Shaft Dia.: 1.000"
Front Spline Tooth Count: 30

Heavy Duty Input Shaft 30280-01

For use without internal turbine support bushing in converter.

Shaft Material: 300M
Shaft Dia.: 1.000"
Front Spline Tooth Count: 30

Heavy Duty Intermediate Clutch Backing Plate 34144HD-01

.375" Thick

Heavy Duty Main Shaft 34672-01

Material: 300M

Pinion Pin 34875-01

Fits output and reaction planetaries for all model years.

Helps cure:

Lost or damaged component

Pinion Thrust Washer 34875-04

For output and reaction planetaries, fits all TH400, 4T65-E and '98-earlier 4L80-E with .750" wide pinion gears.

Helps cure:

Lost or damaged component

Pinion Washer 34875-03

For output and reaction planetaries

Helps cure:

Lost or damaged component

Planetary Rebuild Kit 34875RK

For output and reaction planetaries, fits all TH400 and '98-earlier 4L80-E with .750" wide pinion gears.

Helps cure:

Lost or damaged component

Rear Unit Endplay Shim 34006-05

.005" Thick

Material: Steel
Inner Dia.: 2.375"
Thickness: 0.005"
Outer Dia.: 3.250"

Helps cure:

Excess rear endplay

Rubber Clutch Separator ORCS-070-380

For use with frictions about .060" thick.

Material: Silicone Rubber
Dia.: 0.070"
Length: 0.380"

Rubber Clutch Separator ORCS-103-380

For use with frictions about .080" thick.

Material: Silicone Rubber
Dia.: 0.103"
Length: 0.380"

Smart-Tech® Drum Module 34555-01K

For racing applications that do not use front band.

Linkage

Shift Lever Kit 38512-01K

Pump

Big Shaft Stator Support Tube Kit 28154S-125

Boost Valve Kit 34910-05K

Factory Style, No O-Rings

Helps cure:

Low line rise
1-2 Soft
2-3 Soft
Delayed Reverse
Reverse shudder

Boost Valve Kit 34910-01K

O-Ring Style

Helps cure:

Low line rise
1-2 Soft
2-3 Soft
Delayed Reverse
Reverse shudder

Front Pump Bolt 28136

Thread Style: 5/16-18
Length: 1.375"

Line Pressure Booster Kit 400-LB1

Pressure Regulator Valve Kit 34910-03K

Fits '71–later units.

Helps cure:

High & uncontrollable line pressure
Delayed converter charge
Poor Reverse engagement

Pump Bushing 34234B-01

Bushing Style: Precision
Material: Bronze

Pump Bushing 34034T-01

Pump

Bushing Style: Precision
Material: Steel-backed bimetal
Width: 0.615"
Shaft Dia.: 1.873"
Housing Bore: 2.001"

Stator Support Bushing 35007A

Bushing Style: Precision
Material: Steel-backed copper alloy
Width: 0.500"
Housing Bore: 1.121"
Inner Dia.: 1.004"
Shaft Dia.: 1.002"

Helps cure:

Bushing wear
Bushing failure

Stator Support Shaft 34910S-01

Valve Body (View Valve Body Layout Diagram)

Checkball 10000-08

Material: Imidized Plastic
Dia.: 0.250"

Helps cure:

Lost or damaged component

Case

Case Bushing 34006-SP

Case, No Walk Out"

Material: Bronze
Bushing Style: Precision
Width: 0.630"
Shaft Dia.: 2.006"
Housing Bore: 2.129"

Helps cure:

Bushing walks out

Case Saver Retainer 34762-10

Fits all TH400 and '98-earlier 4L80-E.

Heavy Duty Case Bushing Kit 34006-SPB

Manual Shift Shaft Kit 38511-05K

Helps cure:

Lost or damaged component

Oil Pan Stud Kit 28711-01K

Servo/Band

Adjustable Rear Servo Pin Kit 34912-01K

Fits all TH400 & '95-earlier 4L80-E.

Heavy Duty Low/Reverse Servo Piston 34914-01

Fits all TH400 & '95-earlier 4L80-E.

Tech Resources

August 12, 2024

4L80-E Shift Lever Kit for Custom Transmission Builds

January 09, 2024

Easy TH400, 4L80-E Reverse Servo Setup: Craft Your Own Tool

Caleb Perham

December 07, 2022

How to Assemble & Install the TH400 Smart-Tech Drum Module

October 21, 2022

FAQs About the TH400 Smart-Tech Drum Module

June 16, 2022

Improve TH400 Performance, Consistency & Safety with the Smart-Tech Drum Module

January 05, 2022

TH400 Forward Drum & Input Shaft Upgrade Options

December 23, 2019

GM 4L80-E, 4L85-E, TH400 Valve Body Layout

October 24, 2018

Clean Up Your Shifts with Sonnax Line Pressure Booster Kits

May 24, 2017

Your Guide to Summer Towing Transmission Repairs & Upgrades

December 23, 2015

Playing with Transmissions: Setting Total Endplay to Prevent TH400 Gear Train Failure

Randall Schroeder

May 19, 2006

SonnaFlow® Chart: TH400 (Normal)

May 19, 2006