Originally Posted by
Fudgey
You're thinking of a dog engagement box, like a seqential gear box.
A straight cut gear is exactly that, straight accross the mating surface. A helical gear kit is tapered to one edge to make it quieter as it has less surface area in contact than than a straight cut gear - hence a straight cut being stronger as there is more metal to metal contact.
A straight cut box will still have sycros, so wont change gear as fast as a dog box.
Pics
Helical top, straight cut bottom
https://www.google.co.uk/search?q=st...3n1brHnyeQjFM:
Syncro left, dog right
https://www.google.co.uk/search?biw=...MiN8jAPy2nDXM:
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.