What issue may occur due to non-parallel spider pin holes?

Non-parallel spider pin holes can lead to a situation where the brake shoes do not align properly within the drum. This misalignment can cause the shoes to track incorrectly as they move against the drum surface during braking. If the shoes are not tracking properly, it can lead to uneven wear on the shoes themselves and potential dragging, which may also affect braking performance. Proper alignment is crucial for effective braking, and any deviation caused by non-parallel pin holes compromises the uniform contact needed between the shoes and drum, ultimately impacting the vehicle's ability to stop efficiently.