Transmission Parts GM 4L80-E 4L85-E Valve Body Valve / Sleeve
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Symptoms:

  • OD roller clutch failure
  • No Forward
  • Overrun clutch distress

Cause:

Lack of sufficient holding power in the overdrive roller clutch.

Correction:

Apply the overrun clutch in all gears except OD 4th, reinforcing the roller clutch to adequately support heavy loads.

4L80-E, 4L85-E

Smart-Tech® Overrun Clutch Valve Kit
Part No. 34200-40K

Fits units '97-later.

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Insufficient holding power in the overdrive roller clutch is the underlying cause of chronic overdrive roller clutch failure in hardworking 4L80-E and 4L85-E transmissions. When the roller clutch fails, the damage can be catastrophic and the only fix is replacing the drum, planetary assembly and mating components.

The Sonnax Smart-Tech overrun clutch valve kit 34200-40K offers a hydraulic solution to this known mechanical problem. With unique rerouting of hydraulic fluid pressure, this patented kit keeps the overrun clutch applied at all times (except OD 4th), reinforcing the roller clutch to adequately support heavy loads.

  • Improves OD roller clutch holding power in D4 and Reverse ranges
  • Extends the life of workhorse transmissions while preventing warranty claims and comebacks
  • Installs quickly onto the valve body — no transmission removal needed
Range Gear Overrun Clutch with
Sonnax 34200-40K
Clutch Valve Kit		 Overrun Clutch
with OE
Clutch Valve
Park Applied
Reverse Applied
Neutral Applied
Overdrive 1st Applied
2nd Applied
3rd Applied
4th
Drive 1st Applied Applied
2nd Applied Applied
3rd Applied Applied
D2 1st Applied Applied
2nd Applied Applied
D1 1st Applied Applied

Any other modifications to the valve body should be completed prior to installing Sonnax Smart-Tech® overrun clutch valve kit. With minor lube tube modification, the Sonnax kit can be installed in ’92-’96 units. Please contact Sonnax Product Support via email or by calling +1 (802) 463-0288.

  • Socket-Head Cap Screw Long
  • Socket-Head Cap Screws (2) Short
  • Button-Head Screws (2)
  • Retaining Pins (2)
  • Valve Manifold
  • Short Tube
  • Long Tube
  • S-Shaped Bracket
  • Flat Bracket
  • L-Shaped Bracket
  • Gasket
  • End Plug
  • Valve
  • Spring
  • Sleeve
  • Tabbed Bore Plug
  • O-Rings (3) 1 Extra
  • Cap Plugs (2)
  • Aluminum Plugs (2) Small, 1 Extra
  • Rivets (2) 1 Extra, Not Shown
  • Alignment Pins (2)
  • Drill Jig
  • Drill Bit Small (.109" dia. )
  • Drill Bit Large (.180" dia.)

Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.

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

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

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  • 4L80-E, 4L85-E Smart-Tech® Overrun Clutch Valve Kit 34200-40K

Videos

Basic Installation Steps for the Smart-Tech® Overrun Clutch Valve Kit
 

Related Sonnax Parts

Required

Recommended

4L80-E, TH400 Case Saver Retainer 34762-10

4L80-E, TH400

Case Saver Retainer 34762-10

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

Required

Recommended

4L80-E Case Saver Retainer 34762-20

4L80-E

Case Saver Retainer 34762-20

Fits '99-later 4L80-E.

Required

Recommended

4L80-E, 4L85-E Heavy Duty Remanufactured Valve Body GM033

4L80-E, 4L85-E
Heavy Duty Remanufactured Valve Body GM033

Fits '97–'03 units. Smart-Tech® overrun clutch valve kit installed.

Required

Recommended

4L80-E, 4L85-E Heavy Duty Remanufactured Valve Body GM030

4L80-E, 4L85-E
Heavy Duty Remanufactured Valve Body GM030

Fits '04-later units. Smart-Tech® overrun clutch valve kit installed.

Required

Recommended

4L80-E, 4L85-E Reverse Servo Spacer Kit 34528-01K

4L80-E, 4L85-E

Reverse Servo Spacer Kit 34528-01K

Fits '96-later.

    Helps cure:
  • Broken Low/Reverse servo piston
  • No Reverse
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