March 02, 2017
It’s Snow Plowing Season Again! Understanding 4L80-E Overdrive Roller Clutch Failure
Jim Dial
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.
View Instructions Find a DistributorInsufficient 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
March 29, 2017
Transmission Report: Sonnax Voted Tops for Parts & Tools!
June 22, 2017
Outsmarting 4L80-E Overdrive Roller Clutch Failure
June 22, 2023
4L80-E Performance & Heavy-Duty Transmission Build Guides
-
Patent
- 10,161,505
Videos
Basic Installation Steps for the Smart-Tech® Overrun Clutch Valve Kit
Related Sonnax Parts
Required
Recommended
4L80-E, 4L85-E
Reverse Servo Spacer Kit 34528-01K
Fits '96-later.
-
Helps cure:
- Broken Low/Reverse servo piston
- No Reverse