Not compatible with '64-'66 TH400 main shafts with major diameter of spline about .980”. To use the Sonnax hubs in these early units a 67’-later main shaft with major diameter of spline about .970” must be used.
Sonnax extreme duty forward clutch hub kit 34322-02K is manufactured from forged 4140 steel and features nitrited and case-hardened splines to eliminate spline wear in extreme applications in GM TH400, TH425, 4L80-E and 4L85-E units. Kit includes a bearing between hub and direct clutch housing. The case-hardening at bearing surfaces is removed to make further modifications easier. This forward clutch hub and bearing combination shifts the support of the forward clutch hub from the main shaft to the direct housing and sun gear shaft.
Compared to OE or other replacement forward clutch hubs, Sonnax extreme duty forward clutch hub kit 34322-02K has an additional .025” thickness designed-in to reduce endplay and provide further endplay adjustment options. No machining is required for typical installation.
Hub outer spline length is increased by .055" to allow additional clutch with shortened piston. This added length does not interfere with normal piston travel and can be used with any piston without modifications.