Synchronizer Operation Explained

Manual Transmission Synchronizer Operation Explained.

[@5CGQ]

What most people don't appreciate is that "grinding gears" isn't damaging the actual gears that transmit power, but the dog teeth on the synchro system.

[@DrivelineMaster]

You are absolutely correct.

[@dangeary2134]

Makes me appreciate that big truck transmissions generally do not have synchronized gearsets. I had to rebuild an entire transmission when someone had broken the main output shaft in one. No books, no drawings, nothing but brute competence. I will say, the way that they are made with dual or triple countershafts, the design is ingenious. The input and output shaft are only connected by a pilot bearing. The fact that the main output was snapped into two pieces, and the transmission didn’t fly apart is testament to the designer! The countershafts held the gears in their proper location, even though the shaft was toast! No synchronization there, just a good gear matching hand was required!

[@mikekokomomike]

I have a Kawasaki motorcycle and the factory service manual chapter on repairing the transmission has one line about " paying attention to the mating dogs ". Made me chuckle.

[@josephschaefer9163]

Not if you have old stuff with slider gears

[@josephschaefer9163]

@Franky997 grinding gears on old stuff like '47 chevy, farmall tractors, or cub cadet lawn mowers does damage the actual gear teeth. The whole gear slides to engage

[@anthonygonzalez-oit9299]

This was really well explained. The video at the end really capped it off and pulled it all together for me. Thanks.

[@Danielagostinho21]

Using a strobe light to see gears at speed mesh, Brilliant!

[@mathewshackelford8037]

Works just like a timing light

[@jptrainor]

Best and only video of a synchronizer in live operation that I've seen.

[@ComMando9100]

I wish teachers at school would teach the same way. Amazing video with lots of different presentations, I don't think this could be explained any better than this!!!

[@sarthak_18]

Really sir you said true thing

[@rogergummer5173]

Given the hard job, its a reasonably good explanation.

[@mikes9939]

Would be good to explain that the synchro ring is made of brass hence it's gold color. Brass is softer and is sacrificial meaning it will eventually wear out and need replacement. Brass is the perfect companion metal to press against the hard steel gear and do no damage to it as it tries to either speed it up or slow it down so the the synchro hub can slide over and complete the lockup. It's important to remember that the synchronizer assembly must adjust the speed of the entire cluster gear and input shaft including clutch disc in order to perform the lockup into the selected gear. Quite a task and shows why you must have clean clutch release so that the disc is completely free to rotate. This is a very good video, especially with the gear train illuminated with the strobe light to show what happens.

[@DrivelineMaster]

Thank you for your good comments. You are correct. One note. although these blocker rings are brass there are other blocker rings made of other materials and sometimes either lined with a friction material similar to brake lining and others that use a bi-metal design with a sintered metal inner cone that is soft with a high coefficient friction. I will consider a followup video with this additional information.

[@shaggydogg630]

We had some Mustangs rings made of paper! Replaced many.

[@Kevin-mx1vi]

​@@Franky997Can confirm that because some years ago I worked for a company that made synchromesh rings for many of the major European car manufacturers. Selector forks were also made from phosphor bronze, but of a different grade.

[@maneki9neko]

This is terrific. Details like the back cut on the engagement teeth on both the synchronizer sleeve and the speed gear, are new to me. This is shown under magnification at 2:15, and is easily missed when you have the parts in your hand. This back cut is what holds the two parts together under load, and prevents the car from popping out of gear. When an older transmission pops out of gear people will tell you with authority and confidence: 'oh, the synchronizer rings are bad'. But the synchro rings have little to do with this function. However when this tiny back cut, on on the engagement teeth of the speed gear or the synchronizer sleeve is worn away, there is nothing left to hold speed gear and sleeve together. In this case a new set of synchro rings will do nothing to fix the problem. And that is very much worth knowing.

[@DrivelineMaster]

Thank you for your comments. Please note that the back cut is not present on all synchronizer sleeves and gears. I see it missing mostly on older transmission designs. There are several reasons why a transmission will jump out of gear and worn out back cut is one of them. Normally what happens is the oil is not changed when it should be and or the driver is rough on the transmission and the blocker rings start to wear causing grinding (gear clash) which in turn chews up the clutching teeth on the gear and on the sleeve which wears away the back cut. It's often a domino effect.

[@getplaning]

I have overhauled countless gearboxes, measuring gaps and replacing parts, but this is the best explanation of how a gearbox works that I have ever seen.

[@DrivelineMaster]

Thanks for the compliment.

[@spacetrace7021]

The ability or willing to show what you explaining just earned you a subscriber.

[@OverlyCuriousEngineer]

One of the best videos i have ever watched about synchro mechanism. Incredible presentation.

[@DrivelineMaster]

Thank you

[@maneki9neko]

Yes. He really has all the fine details down. Gear boxes for Spec Miata racing are rebuilt all the time. However the re-builds tend to have problems. If a rebuilder replaces the bearings, the brass synchro rings, and the seals then the gearbox will shift into gears easily and the box will hold oil, but will it stay in gear? Apparently if the back-cut (2:15 in the video) on the engagement teeth between speed gear and synchro sleeve are worn, these parts need to be replaced too. Someone who is simply installing a 'rebuild kit' will miss this.

[@abhijeetchilwirwar722]

A great video , actually had doubts about the internal shafts used and the sleeve and gear engagement but this video had it all covered

[@NickGiamattiKeyWest]

Fantastic presentation!....Great technical detail & functional explanation! Strobe light visual on the Rotating System really brought-it-all- together! Thank you!

[@jerryscared]

Great video! Wonderful explanation. I especially appreciated the summary in the beginning of the three functions of the synchronizer.

[@adamapostolos781]

Thank you for explaining & animating, this technology is becoming clearer, thank you

[@LEDRavecom]

Wow, using the strobe light to show synchronizer at work is brilliant! Thank you!

[@Kimbeattie]

Great video and the strobe light showing the operation was brilliant thanks from Canada

[@maxwelld3753]

Never understood how they worked until I watched this. Very well done.

[@chimeragaming56]

really nothing beats a good explanation and some actual footage or hands on with my actual hands. ty for this.

[@frankcastle8349]

Thanks for the video! An excellent explaination,best on YT for gears.

[@aniruthdinesh9156]

Awesome Presentation, now I understand how this really works!

[@kengarcia1461]

Really good, well explained and easy to understand demonstration. Thanks for making and sharing this video

[@elora2525]

The best video for ASE, I watched this video 2 times before the test and still didn't pay enough attention. This video need to be watch 3 times for ASE manual transmission test

[@gsheverything_2716]

Why the test, if you don't mind me asking???

[@doublebass3858]

very good explanation. The only video I found that explains the synchronizing gear in great detail

[@DrivelineMaster]

I'm glad this worked out for you.

[@DORVALFAGUNDES]

Drivemaster, you're the best Master. My language is Portuguese, but I didn't understand the Brazilian videos and I understood your video. I didn't understand how the synchronized ring works but thank for you, I understand now.

[@DrivelineMaster]

Your Welcome

[@OwensGarage]

Excellent video, thank you. You just filled up another small gap in my mechanical knowledge.

[@georgespangler1517]

Thanks,,,great informative vedio of the operations

[@pablogarciavasquez6637]

¡EXCELLENT MASTER CLASS AND GREAT TEACHER GREETINGS FROM LIMA PERU!

[@chadportenga7858]

Thank you! The demonstration of the synchro in action at 7:00 helps it all make sense. (The first part of the video is the nitty gritty of what makes it work. The demo shows it in action.)

[@lovesjw]

Applause! Real gentlemen applaud this good video!

[@xavieraxiak6866]

As the sleeve moves towards the speed gear, the keys weakly push the blocking ring ahead until the conical friction surfaces make contact. The resulting frictional torque rotates the blocking ring so that it's teeth are 1/4 tooth pitch misaligned with the sleeve teeth which causes contact of the teethes' angled surfaces. This is called "energizing". As well as causing the blocking teeth to block the sleeve, the sleeve can now apply a strong force to the blocking ring via the tooth contact, increasing friction and synchronizing torque.

[@diegorodriguez-lk8of]

Great fucken video don't give up you'll be up to 1 million subscribers soon. Best of luck and thanks for making things clear and simple to understand

[@Tedminat0r]

Brilliant idea with the strobe light. Thanks!

[@dalekrinke2674]

Very good explanation of this mechanism. Thank you a bunch for your time and experience! 👍👍

[@cncn9631]

Its Amazing teach Video I Ever Seen. Good Jobs

[@jacobwarrington1904]

Thanks for the video! Helped me study.

[@Bushybowl]

Excellent job on the video, structured and explained perfectly and pleasure watching

[@katojeremiahcsfg4274]

Liked the way you tried everything to make us get the idea, thanks

[@nickayivor8432]

Thanks for sharing what you know with us brilliant video tutorial amazing From Nick Ayivor from London England UK 🇬🇧

[@SteveFloresCoach]

This video was great!!! Thank you for it.

[@keitharoo1962]

Wow, did I just learn something today!!!! Thanks!!!

[@johnpower8356]

Great with strobe, I had a 1958 Mack truck when I was young no syncro’s man you had to shift just right, you get used to it. Great video

[@vusindlovu8897]

Simply beautiful 👌

[@jimc6481]

Thanks you, excellent video and explanation.

[@SS-U23]

awesome explanation Thank you

[@billglenn10]

Excellent video and explanation of how this works... Thank you...

[@scattkiwiman]

thank you for showing this !

[@franzjones179]

⭐fantastic video, thanks..!

[@ayiideng5857]

thank you for its very explained and helpful

[@MrsTiaRani]

awesome video, very well explained! many thanks

[@timothycc711]

Great video. Thank you

[@charleskutrufis9612]

Thank You for this video. Very informative.

[@Limeayy]

Woo, this time Manual Transmissions. If i literally had an instructor that taught like this I think it'd go into my head alot easier :P

[@oscarchitsa6548]

Well explained bravo

[@jafersadique7492]

Very informative 👍👍

[@luca490]

Beautiful video sir.

[@edgalaxie]

Excellent video!

[@Engineerboy100]

Wow!!!! That was awesome 👌 thanks you so much for posting.

[@jabberwockytdi8901]

Still the best video on KZbin on this subject

[@DrivelineMaster]

Thank you. This is one of my top videos.

[@utkarshkushwah8800]

Thanks for the such a nice explanatary video...

[@ericbanks6644]

Fantastic video. Thanks!

[@dolins_design]

the strobe light detail was above and beyond and really helped explain it thank you so much

[@DrivelineMaster]

Thanks. I too thought that was a great technique to display moving parts.

[@dolins_design]

@@DrivelineMaster I still dont understand how the sleeve will not engage the gear until the gear speeds are in sync??

[@DrivelineMaster]

This is a very valid question and not an easy concept to understand so let me give this explanation a try. When the sleeve is forced in the direction of the gear to engage then next gear the keys will push on the blocker ring which pushes on the gear. Friction and heat is generated between the blocker ring and the gear. With the heat expansion forces occurs. This expansion from the heat creates a force that pushes the blocker ring and keys back against the sleeve. This force makes it difficult for the sleeve to continue in the direction of the gear until everything is in sync or very close to being in sync. When everything is in sync the friction, heat and resistive force is reduced to a point where the sleeve can now easily slide over and engage with the gear. I hope this makes sense.

[@dolins_design]

@@DrivelineMaster thanks. I did more research today i found that the mass/inertia of the constant mesh gears trying to be slowed by the blocker ring will force the splines to be out of alignment (and unable to engage) until the gear speeds are in sync. Only then can the tapered splines be aligned by the driver pulling the shifter because there is no longer any force "binding" the splines

[@DrivelineMaster]

That is the reason the blocker ring can't immediately synchronize the rotational speed of the gear with the sleeve however it is the friction and the expansion forces that prevent the sleeve from moving over to attempt to lock onto the gear while they are rotating at different speeds.

[@kalef1234]

That strobe demo was great

[@PS_on_youtube]

Very nicely explained!

[@fjs1111]

You did phenomenal work putting this together and your explanations. Learned a few things.

[@DrivelineMaster]

Glad you enjoyed it and found it of value.

[@raymondjames9734]

i want to use this to make a fixed gear / free wheel bicycle hub! never understood this before thank you!

[@JohnSmith-ok9sn]

Exceptional video. Thank You!

[@DrivelineMaster]

John Smith from Plymouth, MI?

[@deepsinghania6496]

This video is clear my concept

[@ScottsGarage17]

Great job explaining!

[@maxenielsen]

Marvelous! Thank you so much!

[@abdullahmohammed2955]

Amazing video thanks alot hope u r having a beautiful life ❤

[@mrbigheart]

thank you, sir. this is highly useful!!

[@shanilkadesilva65]

Great video

[@ryanhewett1663]

very informative; thank you.

[@hagebunshin]

Thank you for this!

[@johng69er]

Great clear video thank you

[@AndreKK-]

Best video on the topic!

[@DrivelineMaster]

Thank you.

[@isabelgarcia891]

Thank you great explanation

[@akashmore9127]

Thanks very well explained 🙏🙏🙏

[@stimpsonjcat67]

Damn fine job on the strobe use!

[@Joeelectronicschematicsforauto]

This was absolutely awesome these videos should be in schools to teach students

[@DrivelineMaster]

They are used in all my classes.

[@elwoodgalapagos1846]

gotta love the reverb on the voice

[@5speedMax]

That is a very cool visual.

[@m.b.smoshitoa8325]

WONDERFUL MY MAN. I DID NOT UNDERSTAND THIS BEFORE BUT NOW I HAVE THE GUTS TIO GO OPEN GEARBOX. LOL MOSHITOA ( S AFRICA)

[@avleerxo]

Great great. It will helpme to modify my 1975 vw bug trans to 5 speed.

[@e-curb]

The first step is to buy the 5 speed conversion kit. It's $2k. Then you have to buy two gear sets ($500). The same co that makes the conversion kits also make a shifter that works with the 5 speed ($300). Find a mid 60s core trans to supply you with a few stock parts you will need.

[@romanescalera7752]

Que bueno señor gracias.

[@RC-Heli835]

That is so cool to see it working like it should. My KW T800 has an 8LL and its synchroniser has been very noisy since the heat exchanger went bad and got water into the transmission.

[@DrivelineMaster]

Try Changing the oil and put Redline Manual Transmission Fluid (MTF) in it. This stuff does wonders sometimes.

[@RC-Heli835]

@@DrivelineMaster I just have changed the incorrect 90 wt for 50 wt motor oil. That by its self worked wonders. It made it possible to where the gear shift would actually move the gears in and out. Before that I could take it out of gear and it would stay in gear. It did that one morning until the oil got warm. I ran it all day, came in and drained that 90 wt while hot and its been better ever since. Everything but the synchroniser. So mine is not slowing the gear down when all that noise is going on? I wonder if the air shifter could be sticky somehow?

[@DrivelineMaster]

Unless the manufacture says you can use motor oil instead of GL4 or GL5 gear oil I wouldn't leave the 50st motor oil in your transmission. 90wt gear oil is not the same as it would be if it was 90wt motor oil. The way they measure thickness for gear oil is different than motor oil. Once again I would recommend the Redline MFT. I know it cost more but it is worth it. Unless your transmission was designed to work with motor oil (like some honda's) you will end up damaging your transmission and costing you more $$$ in the long run.

[@RC-Heli835]

@@DrivelineMaster It calls for 50 wt engine oil. Granted Synthetic would be better but we just had a cracked head replaced at 6,389.00 on the truck and now the compressor has blown apart on the other truck leaving us stuck with a core fee. Cat wants 1,500.00 just for the core fee alone. Fleet Pride got us a refurbished for little over a grand and no core charge.

[@DrivelineMaster]

As long as the factory specification is 50wt engine oil then that is what you should use and have confidence that you won't cause any damage. This is the first trans that I know about that uses 50 wt straight motor oil.

[@BugCrush3r]

excellent description of the synchronizer but I wish you talked a bit more about the locking keys and springs and the purpose they serve

[@DrivelineMaster]

They are not locking keys. They are synchronizer keys. They transfer the force between the sleeve to the blocker ring.

[@DGQ1Q2]

Super goood video thanks

[@anthonyhitchings1051]

thanks so much for this video

[@kidicarus2637]

thanks, very helpful!

[@XyberZyen]

Love that video thx

[@Punjabplus0866]

nice vedio thank u

[@rogerbegin9479]

That was pretty interesting. I never knew how any of that worked.

[@larrydykes7643]

Somebody needed to show this video to my old '67 VW bug.

[@ianasogaming8003]

Love you mannn!!!!

[@LibertyWarrior68]

I'm getting ready to rebuild my gearbox, so I'm learning as much as I can.

[@timsexton]

That was great!

[@muchayomudawako353]

Thanx for the video

[@andrewhanson5942]

Now THAT is some high tech mechanical engineering!

[@dulcevendetta]

thanks data!!