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).

400, 4L80-E, 4L85-E

Extreme Duty Main Shaft
Part No. 34672-05

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Main shaft failure is a common problem in extreme duty GM 400, 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.

  • Top-notch engineering and precision manufacturing deliver unrivaled performance and durability in the 1” stock size
  • Rear spline prevents the rear internal gear journal-end from twisting off by engaging the full internal spline of the gear
  • Extensive in-vehicle and lab testing with unbroken performance

Can be used to replace late 4L80-E and 4L85-E solid shafts, however, check clearance between front of main shaft and rear of input shaft. It may be necessary to remove approximately .060" from front of main shaft or rear of input shaft.

  • Material: Aermet
  • 400, 4L80-E, 4L85-E Extreme Duty Main Shaft 34672-05