4L80E, 4L85E

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.

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.

This Sonnax Smart-Tech overrun clutch valve kit 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

Note:
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. 

Contents:

• 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
• Alignment Pins (2)
• Drill Jig
• Drill Bit Small (.109" dia. )
• Drill Bit Large (.180" dia.)

SONNAX Installation Instructions