300M Input Shaft

The Sonnax 34670-01 input shaft is a performance upgrade designed to combat the common input shaft failure in high-performance and heavy-duty GM 4L80-E and 4L85-E transmissions. Engineered from ultra-strong 300M alloy steel, this shaft undergoes proprietary heat treatment and post-processing for exceptional durability. The design specifically reinforces the outer diameter (O.D.) carrier spline, a typical failure point. By eliminating the OE undercut and increasing spline material at the major diameter, the shaft fills the root gap of the internal O.D. carrier spline, resulting in dramatically improved structural integrity. This advanced torsional design also includes refinements to the spline and cross-hole for added resilience. Recommended for applications handling up to 1,000 horsepower, the Sonnax 34670-01 input shaft is a robust solution for demanding builds. Installation requires an experienced technician and necessitates transmission removal.