Extreme strength spline configuration requires use of thrust bearing between forward clutch hub and direct drum that moves support of forward clutch hub from the main shaft to the direct drum/sun gear tube (see instructions Figures 1 & 4).
Main shaft failure is a common problem in extreme duty GM TH400, 4L80-E and 4L85-E units. OE and aftermarket shafts simply don’t hold up in extreme horsepower applications, leading to spline twist and shaft breakage. Sonnax extreme duty main shaft 34672-05 is manufactured from an exceptionally tough high-strength Aermet steel alloy with proprietary heat treatment for unrivaled performance and durability. An advanced torsional design with spline and cross-hole refinements make this the most durable 1" main shaft available. This shaft withstood extensive track and lab testing with unbroken results in the most extreme applications. Recommended for applications above 1,000HP. For street/strip performance and heavy duty applications, see Sonnax heavy duty main shaft 34672-01.