Originally Posted by Marc sierra

Well actually a straight cut gear is less strong than a helical cut gear as the straight gears have less area to be in contact with the other gear. The problem though with helical gears is that they put a side loading on the bearings of the gearshaft. So basically the gears try to push away from each other. If there is a bit of play on the shaft the contact area of the gears becomes less and the teeth can break.

Originally Posted by stevieturbo

Helical gears are quieter, more contact patch AND stronger than straight cut gears. It's also the helical profile that makes them quiet.

But typically straight cut gears tend to be sold as stronger because they're aftermarket, made for racing and made from stronger materials than OEM stuff.
But like for like, helical IS stronger. But helical also imparts side loadings onto the system which can affect case strength, bearings etc whereas straight cut doesnt do this quite the same.

And depending on geometry used for the gears, some SC gears can be bloody noisy, although mostly that's a thing of the past too. Most should be quite tolerable even in a road car as long as the gearbox isnt bolted solid to the car ( and then it can be feckin horrific lol )


And a straight cut box...will have straight gears. That has no baring on the shift mechanism. They can be made with both synchro engagement or dog engagement. Entirely up to the buyer to decide what they want.