February 22, 2016
Too Close For Comfort: Pinpointing 4L60-E Gear Train Assembly Problems
Steve Garrett
Earlier versions of this kit required an aluminum forward piston. It is recommended to follow the specific instructions provided during assembly to avoid a mismatch of parts.
OE Part No. 17803689, 08663580
View Instructions Find a DistributorLimitations of the GM 4L60 series OE input housing are the root cause of 3-4 burnup in performance applications. The weak OE backing plate flexes during clutch apply, allowing heat to build up unevenly within the clutch pack’s limited space. Stop the flex and you stop 3-4 clutch failure.
Sonnax Smart-Tech input housing kit 77733-10KB makes room for a taller clutch pack anchored in place by a stronger backing plate — the most reliable way to increase clutch capacity and protect against destructive heat.
To avoid the problems found with older, OE housing designs, Sonnax starts with the latest production, new housings from GM. These improved housings have splines for the input shaft that are cut at minimum spec for reliable shaft retention and sealing. The housings also benefit from added material for a thicker, more consistent cross-section that protects against breakage.
Smart-Tech input housing kit with heavy duty input shaft 77733-10KB fits 298mm torque converter units. The shaft is manufactured from 300M ultrahigh-strength steel for exceptional toughness and resistance to fracture. It features a revised turbine end spline without an undercut where OE shafts commonly break. Both the housing and shaft also are available separately.
Requires ’91-later 3-4 apply ring; requires ’97-later ring gear; requires ’97-later dual-cage return spring; requires ’87-later forward backing plate; requires ’97-later stamped steel forward piston. Cannot be used with aluminum forward piston or Sonnax billet forward piston 77764-01. See instructions for further detail.
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