Why do we use spur gear in reverse in manual transmission instead of helical gears?
( We use helical gears in forward movements and it`s smoother than spur gear in movements)
Helical gears are hard to engage and disengage. Since the forward gears are always engaged, it makes sense to use helical gearing (sturdier, can handle more load, etc.) Since reverse uses and idler gear which needs to be engaged and disengaged, the spur gear is much easier to use. Check out the source… Gives a full explanation. Hope this answers your question.