4L80-E Performance & Heavy-Duty Transmission Build Guides

Sonnax 4L80-E transmission parts make it easy to add unmatched reliability to vehicles of any power level, from hardworking trucks to extreme street/strip race vehicles. Check out these handy Sonnax build guides to get maximum results out of your rebuild. Many parts listed here also fit 4L85-E and/or TH400 units.

• Heavy Duty Truck Basic Build
• High Performance Build (Under 1,000HP)
• High Performance Build (Over 1,000HP)

Heavy Duty Truck Basic Build

Pump/Valve Body

• Smart-Tech^® Overrun Clutch Valve Kit 34200-40K  Details
• Lube Regulated Pressure Regulator Valve 34200-14K*
• Line Pressure Booster Kit 4L80E-LB1*

Internal

• Heavy Duty Forward Clutch Hub 34322-01
• Heavy Duty Clutch Retaining Ring 28124*
• Case Saver Retainer:
  '98-Earlier 34762-10
  '99-Later 34762-20*

Servo

• Adjustable Rear Servo Pin Kit '95-Earlier 34912-01K
• Reverse Servo Spacer Kit '96-Later 34528-01K*

Case

• Heavy Duty Case Bushing Kit 34006-SPB*

*For a more comprehensive build that maximizes transmission performance and durability, use Sonnax Performance Pack HP-4L80E-01 in place of these components.

High Performance Build (Under 1,000HP)

Comprehensive Shift Upgrade Kit (Pump/Valve Body, Internal, Servo & Case)

• Performance Pack HP-4L80E-01 Details

Pump/Valve Body

• Smart-Tech^® Overrun Clutch Valve Kit 34200-40K Details

Internal

• Heavy Duty Forward Clutch Hub 34322-01
• Heavy Duty Input Shaft 300M Steel 34670-01
• Heavy Duty Main Shaft 300M Steel 34672-01
• Heavy Duty Intermediate Clutch Backing Plate:
  '98-Earlier, .375" Thick 34144HD-01
  '99-Later, .275" Thick 34144HD-02

Servo

• Adjustable Rear Servo Pin Kit '95-Earlier 34912-01K
• Heavy Duty Low/Reverse Servo Piston:
  '95-Earlier 34914-01
  '96-Later 34914-02

High Performance Build (Over 1,000HP)

Comprehensive Shift Upgrade Kit (Pump/Valve Body, Internal, Servo & Case)

• Performance Pack HP-4L80E-01 Details

Pump/Valve Body

• Smart-Tech^® Overrun Clutch Valve Kit 34200-40K Details

Internal

• Extreme Duty Forward Clutch Hub Kit 34322-02K
• Extreme Duty Input Shaft Aermet Steel 34670-02
• Extreme Duty Main Shaft Aermet Steel 34672-05
• Heavy Duty Intermediate Clutch Backing Plate:
  '98-Earlier, .375" Thick 34144HD-01
  '99-Later, .275" Thick 34144HD-02

Servo

• Adjustable Rear Servo Pin Kit '95-Earlier 34912-01K
• Heavy Duty Low/Reverse Servo Piston:
  '95-Earlier 34914-01
  '96-Later 34914-02

About the Performance Pack

The Sonnax 4L80-E, 4L85-E Performance Pack is the most complete upgrade kit for top-quality builds.

• Innovative components work together to precisely recalibrate pressures and shift accumulation, delivering firmer shifts under load without sacrificing low-speed drivability

• To target common wear areas in the transmission, the kit includes many improved parts to repair damage, prevent future wear and improve reliability

• While many components also are sold separately (including those marked with a * on the heavy-duty truck basic build), some are available only in the Performance Pack.

About the Smart-Tech Overrun Clutch Valve Kit
See part details for important fitment and installation notes.

Insufficient holding power in the overdrive roller clutch is the underlying cause of chronic OD roller clutch failure in hardworking 4L80-E and 4L85-E transmissions. The patented Sonnax Smart-Tech overrun clutch valve kit improves OD roller clutch holding power in D4 and Reverse ranges to guard against failure and catastrophic transmission damage.

The Smart-Tech kit installs quickly onto the valve body — no transmission removal needed. It is also available pre-installed on a Sonnax heavy duty remanufactured valve body.