Mfg/N 34091-85 Inner bearing race has been used on Big Twins since 1985.
The inner primary bearing rides on this race. By design, this race press-fits onto the transmission mainshaft; this system works fine for stock engines.
100 HP+ engines will make this race walk on the mainshaft; if it walks inboard, it will damage the maindrive gear seal and cause a transmission oil leak; if it walks outboard, it will cause a primary oil leak
The high torque bearing kit eliminates this condition.