Ok why do I have double or triple syncro gears… and why does my 5th grind unless I double clutch…
oh and NO transmissions are magical… although I have swapped out the 5th gear in my jetta… I still don’t know the names of any parts… I took it apart and put it together with the new parts the same why it came apart…
The bigger question really is did you know the gears in a synchronized transmission are always meshed? Most people don’t know that, they think the grinding you hear is the actual gears.
Ah I think you mean dual “cone” or triple “cone” synchros. I know very little about synchros besides the definition, and a vague picture I have in my head that is probably completely wrong.
the gear rests on the main shaft with a bearing between the shaft and gear the gear is meshed with a gear on the output shaft.
the hub slides on the main shaft, there are teeth that mate with the main shaft and are kept in by snap rings.
the blocker ring is between the hub and gear…on T56’s at least, the blocker ring rests on the gear with a friction surface (much like auto clutch dics i believe, but dont quote me on that ive never built an auto so idk really) and is a cone shape. when you shift the output shaft is connected to the input shaft because the gear is now spinning with the input shaft because of the hub. so the gear sits idle untill it mates with the hub which causes it to spin.
i could probably draw it better than i can explain it, hopefully this is somewhat a productive post and not just rambling…
I agree with how most guys will understand the concept, but have absolutely no idea what’s actually happening.
I could not draw anything that would even resemble the process, but then again I’ve never really looked into it. I’ve yet to do any serious transmission work.
I’m assuming they act like a friction block in a machine gun. As the bullet comes out of a gun, the bolt assembly slides back, but still has to give the bullet support so they use a pressure friction block in some guns. It slows the bolt down in proportion to energy difference.
So I’m guessing the synchrony of gears would work in the same manor. I would assume there is a small friction surface, where the two gears can “share” rotational energy, allowing them to mesh more easily because they will be at a closer speed.
I’m assuming double clutching helps because if you shift at red line, everything would be spinning at 7K rpm’s. The syncros might be worn out a little or incapable of slowing down in the time you want to shift in. So double clutching will slow down the components inside the tranny making it easier on the syncros to match speed…
That all an educated guess though. I really have no idea.
if your banging out shifts in your car, when you get to redline and upshift the syncros actually slow down the gears and mainshaft until the collar slides in to couple it to the countershaft, because the countershaft is gear coupled to the final drive but the mainshaft and associated gears in an upshift are spinning faster than it since everything is constant mesh (this is in hondas). You can get faster shifts if you have a higher coefficient of friction in the cone area and also if you have less inertia on the mainshaft and associated equipment, like lighter clutch disks. Even though you are slowing the gear down on the countershaft, its on bearings and its coupled to the mainshaft because everything is constant mesh, and the less inertia will let the mainshaft and gears slow down faster, thus slowing down the countershaft gears so the syncronizer has less work to do even though the gears are on bearings (think of a lightweight flywheel vs regular flywheel) so in effect, the syncronizer must help slow down the mainshaft and ALL the gears in the transmission to match the gear speed to the countershaft/final drive speed. Its the opposite if your downshifting.
if your banging out shifts in your car, when you get to redline and upshift the syncros actually slow down the gears and mainshaft until the collar slides in to couple it to the countershaft, because the countershaft is gear coupled to the final drive but the mainshaft and associated gears in an upshift are spinning faster than it since everything is constant mesh (this is in hondas). You can get faster shifts if you have a higher coefficient of friction in the cone area and also if you have less inertia on the mainshaft and associated equipment, like lighter clutch disks. Even though you are slowing the gear down on the countershaft, its on bearings and its coupled to the mainshaft because everything is constant mesh, and the less inertia will let the mainshaft and gears slow down faster, thus slowing down the countershaft gears so the syncronizer has less work to do even though the gears are on bearings (think of a lightweight flywheel vs regular flywheel) so in effect, the syncronizer must help slow down the mainshaft and ALL the gears in the transmission to match the gear speed to the countershaft/final drive speed. Its the opposite if your downshifting.
The only reason I know is because the synchros on my Audi were fucked. And from 1st to 2nd would grind like a mother fucker. I believe synchromesh fixed that problem.