Hard Shifting
Hard shifting may be caused by a mis-adjusted crossover cable. If hard shifting is accompanied by gear clash, synchronizer clutch and stop rings or gear teeth may be worn or damaged.
Mis-assembled synchronizer components also cause shifting problems. Incorrectly installed synchronizer sleeves, struts, or springs can cause shift problems.
Worn, damaged, mis-assembled or leaking hydraulic clutch release system/components can also cause difficult shifting or gear clash.