# Who here knows how SYNCHROS work? **URL:** \ **Category:** NYSpeed Automotive\ **Created:** [June 11, 2008, 9:45am UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859 "2008-06-11T09:45:22Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![BadnewsMike](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/badnewsmike/32/7419_2.png) [@BadnewsMike](https://forums.speedlife.net/u/BadnewsMike)\ **Post date:** [June 11, 2008, 10:47am UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/21 "2008-06-11T10:47:18Z")
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… ---
**Author:** ![Cavi\_Mike](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/cavi_mike/32/5217_2.png) [@Cavi\_Mike](https://forums.speedlife.net/u/Cavi_Mike)\ **Post date:** [June 11, 2008, 10:56am UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/22 "2008-06-11T10:56:33Z")
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. ---
**Author:** ![rdandy5875](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/rdandy5875/32/7511_2.png) [@rdandy5875](https://forums.speedlife.net/u/rdandy5875)\ **Post date:** [June 11, 2008, 10:57am UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/23 "2008-06-11T10:57:27Z")
> [@badnewsmini](#): > > 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… 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. ---
**Author:** ![FBodyMadnezz](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/fbodymadnezz/32/7433_2.png) [@FBodyMadnezz](https://forums.speedlife.net/u/FBodyMadnezz)\ **Post date:** [June 11, 2008, 11:01am UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/24 "2008-06-11T11:01:06Z")
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… ---
**Author:** ![FBodyMadnezz](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/fbodymadnezz/32/7433_2.png) [@FBodyMadnezz](https://forums.speedlife.net/u/FBodyMadnezz)\ **Post date:** [June 11, 2008, 11:07am UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/25 "2008-06-11T11:07:55Z")
> [@newman](#): > > it doesn’t say anything about what is coupled to the shaft. it doesn’t talk about what is decoupled. Is the gear spinning when the clutch is pressed in? if your at a stand still no. if your in between gears ide say yea, just not at the same speed as the engine. ---
**Author:** ![walter](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/walter/32/7202_2.png) [@walter](https://forums.speedlife.net/u/walter)\ **Post date:** [June 11, 2008, 11:19am UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/26 "2008-06-11T11:19:44Z")
> [@Cavi Mike](#): > > 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. That was already covered in this thread, please try again:zong: ---
**Author:** ![ezfd](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/ezfd/32/7334_2.png) [@ezfd](https://forums.speedlife.net/u/ezfd)\ **Post date:** [June 11, 2008, 11:28am UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/27 "2008-06-11T11:28:07Z")
I have an idea, but i could not draw a picture. ---
**Author:** ![Paulo](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/paulo/32/7328_2.png) [@Paulo](https://forums.speedlife.net/u/Paulo)\ **Post date:** [June 11, 2008, 11:37am UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/28 "2008-06-11T11:37:51Z")
Holy shit an intelligent thread. 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. This is interesting. ---
**Author:** ![LUKE\_L](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/luke_l/32/7462_2.png) [@LUKE\_L](https://forums.speedlife.net/u/LUKE_L)\ **Post date:** [June 11, 2008, 11:38am UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/29 "2008-06-11T11:38:30Z")
Good info :tup: I am learning about it more and more lately. I could draw a diagram now better than 15 minutes ago. ---
**Author:** ![Rsnake91](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/rsnake91/32/4996_2.png) [@Rsnake91](https://forums.speedlife.net/u/Rsnake91)\ **Post date:** [June 11, 2008, 12:00pm UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/30 "2008-06-11T12:00:01Z")
lol ive learned something today haha. ---
**Author:** ![Willybeen](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/willybeen/32/7351_2.png) [@Willybeen](https://forums.speedlife.net/u/Willybeen)\ **Post date:** [June 11, 2008, 12:05pm UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/31 "2008-06-11T12:05:30Z")
> [@newman](#): > > yeah. did you know that when you “grind a gear” you are actually grinding the dogs on the gear and the baulk ring? The GEARS never grind unless you shattered one. I DID know that… well the grinding the dogs part… if its anything like on a bike, its a very common problem on motorcycles (yamaha 600rr’s especially) ---
**Author:** ![ultradriver10000](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/ultradriver10000/32/7397_2.png) [@ultradriver10000](https://forums.speedlife.net/u/ultradriver10000)\ **Post date:** [June 11, 2008, 12:35pm UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/32 "2008-06-11T12:35:33Z")
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. ---
**Author:** ![Paulo](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/paulo/32/7328_2.png) [@Paulo](https://forums.speedlife.net/u/Paulo)\ **Post date:** [June 11, 2008, 12:58pm UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/33 "2008-06-11T12:58:08Z")
> [@ultradriver10000](#): > > 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**. So… are you sure? lol ---
**Author:** ![jdmEK9gsr](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jdmek9gsr/32/4995_2.png) [@jdmEK9gsr](https://forums.speedlife.net/u/jdmEK9gsr)\ **Post date:** [June 11, 2008, 12:59pm UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/34 "2008-06-11T12:59:25Z")
> [@newman"](#): > > No cheating and looking at “how stuff works” (although that description is pretty weak) > [@Dr.Stevil](#): > change your poll answer to no cheater! and i agree with jam, the magic of a tranny is beyond me. ---
**Author:** ![LXIFLYBY](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/lxiflyby/32/7399_2.png) [@LXIFLYBY](https://forums.speedlife.net/u/LXIFLYBY)\ **Post date:** [June 11, 2008, 1:58pm UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/35 "2008-06-11T13:58:27Z")
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. ---
**Author:** ![LXIFLYBY](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/lxiflyby/32/7399_2.png) [@LXIFLYBY](https://forums.speedlife.net/u/LXIFLYBY)\ **Post date:** [June 11, 2008, 1:59pm UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/36 "2008-06-11T13:59:55Z")
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. i hope its not too confusing ---
**Author:** ![Cavi\_Mike](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/cavi_mike/32/5217_2.png) [@Cavi\_Mike](https://forums.speedlife.net/u/Cavi_Mike)\ **Post date:** [June 11, 2008, 2:21pm UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/37 "2008-06-11T14:21:38Z")
^^^Holy fucking run-on sentence. I really hope you don’t expect anyone to read that jumbled mess. ---
**Author:** ![66impalass](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/66impalass/32/7429_2.png) [@66impalass](https://forums.speedlife.net/u/66impalass)\ **Post date:** [June 11, 2008, 2:28pm UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/38 "2008-06-11T14:28:20Z")
> [@Cavi Mike](#): > > ^^^Holy fucking run-on sentence. I really hope you don’t expect anyone to read that jumbled mess. how the fuck did you not win worst newb ---
**Author:** ![dawn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/dawn/32/7209_2.png) [@dawn](https://forums.speedlife.net/u/dawn)\ **Post date:** [June 11, 2008, 3:05pm UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/39 "2008-06-11T15:05:04Z")
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. ---
**Author:** ![Skurge](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/skurge/32/7285_2.png) [@Skurge](https://forums.speedlife.net/u/Skurge)\ **Post date:** [June 11, 2008, 3:36pm UTC](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859/40 "2008-06-11T15:36:06Z")
i have a general idea of what they do…but hell if i could explain it lol [Previous page](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859.md?page=1) [Next page](https://forums.speedlife.net/t/who-here-knows-how-synchros-work/49859.md?page=3)