How do they break?

 

It is like taking a OD (outer) gear next to a OD gear (end to end) and what connects the two are a ID (internal) sleeve that has the same gear mesh that the gears have. Take for instance a timing belt has cogs on it, turn it insideout (ID) and you have a gear/the outsidein and you have a (OD). It slides back and forth from one gear to the next, that is if there both at the same speed when doing so. This is where the syncronizers come in. The syncronizers help syncronize or align the gear teeth to mesh to be able to slide from one gear to the next. Go to howstuffworks.com and this will answer alot of questions about transmissions, superchargers, generators and much more. Its a great site. I've been doing mechanic work for years and it still amazes me sometimes. Hope this helps. Oh yeah they break because of lack of lubrication, heat (mileage) and insufficient tme for the other gear to reach the correct speed for them to mesh. At a certain rpm vs. mph the gears can be shifted with NO clutch this is rev matching. This is where the syncros and gear meet a certain threshold where one is slowing and one is ramping up. They have a split second that this happens. I am rambling, make it stop!

 

i'm having my syncros replaced on monday in my 02 GT. should i have them check the gears too from when it would grind while i was trying to shift?

 

thanks for the helpful information. Does power shifting or speed shifting have any effect on them breaking sooner?