Transmission Parts

Browse all Sonnax transmission parts here, or use the filters below to find just what you are looking for.

Find a Distributor

View Sonnax Part Instructions

Enter a Sonnax part number below to view its instructions. For general reaming instructions, click here.

4L80-E, 4L85-E Boost Valve Kit 34200-03K

4L80-E • 4L85-E

Boost Valve Kit 34200-03K

Fits '91-later units with factory-style sleeve, no O-rings. Can be retrofitted to '89–91 units. See instructions for details.

    Helps cure:
  • Uncontrollable line rise
  • High line pressure
  • Broken parts
  • Broken clutch piston
4L80-E, 4L85-E Boost Valve Kit 34200-10K

4L80-E • 4L85-E

Boost Valve Kit 34200-10K

With encapsulated relief valve. O-Ring style

    Helps cure:
  • Uncontrollable line rise
  • High line pressure
  • Broken parts
  • Broken clutch piston
4L80-E, 4L85-E Boost Valve Kit 34200-01K

4L80-E • 4L85-E

Boost Valve Kit 34200-01K

O-Ring style. Kit can be retrofit to back to '89 units. See instructions for details.

    Helps cure:
  • Uncontrollable line rise
  • High line pressure
  • Broken parts
  • Broken clutch piston
4L80-E, 4L85-E O-Ringed End Plug Kit 34200-05K

4L80-E • 4L85-E

O-Ringed End Plug Kit 34200-05K

TCC & PR Valves

  • Dia.: 0.625"
    Helps cure:
  • Pressure loss
  • TCC apply concerns
  • Burnt clutches
  • Harsh shifts
  • Soft shifts
↑