ok i have been waiting for the oppurtunity to make a thread on this and a customer dropped one off so that i can show you whats goin on with our tranny's.
I'm not going to bother with all the b.s. but rather get right to the point.this trans is out of the car and already torn down .
here without the forks and all gears labeled
ok now you have an idea of what it looks like inside lets get to business.take a look at the 3/4 synchronizer since this is where majority of the problems exist.here is a closer look with 4th gear removed
right above the sync there is supposed to be a snap ring that holds the sync in place.this snap ring is what seems to be the most popular of breaks.the reason why it breaks is due to excessive force when shifting from 3rd to fourth gear.because of the motion of shift being towards you and in the heat of the moment your adrenaline is rushing you can really yank on it and force it into gear.by doing this the sync,blocker ring and gear are trying to mesh together to apply the gear.if it is not fully applied,too much force is transmitted through the fork and sync and ultimately cracks the snap ring that holds it in place.what happens next is the biggest problem.underneath 4th gear there is a caged needle bearing that looks like this
once that snap ring breaks every shift from 3rd to fourth will result in the sync moving upwards into the needle bearing and cracks the plastic cage that the bearings sit in.this causes bearing failure and in this particular case,fourth gear locked up while still in 3rd and catastrophic failure occured.see illustration below
you can also see in this pic that the input shaft was damaged as well due to bearing failure
heres a pic of the snap ring broken in its position
now there alot of other things that can go wrong with the trans.ive done quite a few that just the 3/4 synch just gets worn and grinds going into third but i think the biggest problem is the snap ring.
now how to eliminate the problem..thats a whole different vegetable!.i dont have resources for custom gears and what not but heres what im thinking.the synch itself wouldnt have this problem if it was welded to the shaft...the only problem is if you ever wore down the sync you wont be able to change it so thats pretty much out the door.now if someone could make a slightly undersized sync then it would have to be pressed on to the input shaft i think that will solve alot of the problems.i dont know but i would love to discuss this with someone who can make their own gears or other engineering experience that could shine some light to make it better
what are your opinions?
jay
