Synchronizer Choice

[broncc]

Hello all,

I'm putting one transmission together out of two and I noticed that they have different styles of synchronizer. Avoiding the ehtics of reusing a wear item, I'd like to learn something about them.



The top is an aftermarket from a previously rebuilt transmission. The bottom is the original one Mazda put in. What would make someone choose a synchronizer without friction material? How does this change the engagement? Would this not put metal shavings into the oil?

 

[Shran]

Most I've seen look like the top one, including some transmissions I know haven't been apart since they rolled out of the factory. Why they would change designs, I don't know. The top design has more contact area with the gear, maybe that has something to do with it.