Shimano Nexus 8 Speed Hub Reassembly - Putting It Back Together...

[@RJTheBikeGuy]

For more bike repair videos hit the subscribe button ► bit.ly/SubRJTheBikeGuy

[@MrSlava59]

Подписался на Ваш классный канал !Большое Вам спасибо за интересные и нужные видео пояснения !!!

[@2L40K]

9:05 - the spring does not sit correctly. It must be completely symmetrical, no skew allowed. Here is an old old video on Inter 8: kzbin.info/www/bejne/fmitonZ5oM2Gi7c

[@PiotrK2022]

Next time... Google.com-> Shimano Nexus (model name) service manual and you everything from A up to Z including which one grease and where...

[@robertkat]

You only do that if the parts are free and your time is worth nothing. No warranty for this job.

[@billd6565]

As a Merchant Marine Engineer for more than two decades I’ve overhauled all manner of complex machinery (motors, pumps, purifiers, valves...) but this really challenges your attention to precise assembly. I watched you take this apart, and I was reminded of the old engineering saying that “assembly is never the reverse of disassembly”. Anyone can take stuff apart. Putting it back together is always the challenge. Bravo RJ, I could have used you on the ship.

[@mangoie]

Hey RJ. I had a shifting problem with my Nexus 8, so I found this vid while I was looking for a possible solution. Thanks for such this detailed video, I learned a lot!

[@misterfive5520]

Such a detailed and comprehensive comment yet no more than a 'heart' comment reply. People way too busy nowadays if you ain't bringing value to them.

[@bozhidarvorukov7348]

Yes is roller clutch like one on fly reels or fishing reels. If you reverse the clutch you transfer the fly reel from right hand to left hand. the diagram si.shimano.com/pdfs/ev/EV-SG-8R20-2236G.pdf

[@neilbain8736]

@@bozhidarvorukov7348 This pdf is really useful!

[@dudeonbike800]

Roller or sprag clutch. Too much grease shouldn't be a problem. The accumulated rust on the bearing retainer and perhaps other places might be the culprit.

[@LTPottenger]

Great to hear, I have always thought of getting one of these.

[@davidrjamieson]

Thank you for the detailed video. I was able to fix mine after many attempts. The second spring insert is the trickiest part, and it is what was wrong with mine. The spring has to be inside the upper flange tabs, and outside the lower flange tabs after you tighten it one turn, but it does not want to do that! Several times I thought I had it, but I couldn't get both sets of four gears to work. Upon inspection, I could see the spring was crunched up in the space, but not properly, so the mechanism that gave you the second set of gears was not moving properly. Finally, I had to ask my wife to help, and with four hands available, we got it in correctly, and now it works. Thank you!

[@nickandersonco]

In the first video you didn't have a clue what you were looking at, now you have all the tools and can do the majority of maintenance on those, as well as a decent amount of troubleshooting. Very impressive and inspiring to watch. Thanks again!

[@Antje-Pikantje]

I enjoy repairing stuff on my bikes because they are always very simple mechanical things. This thing however is just unbelievably complicated. Thanks for showing how to take it apart and back together. Even if it still won't work properly, you are my personal hero!

[@jurikristjouw]

it just needs one more spring and clip to be a nuclear bomb... dear lord... After this, I can rebuild the manual gearbox of my car in a heartbeat...

[@josjetwentytwo1540]

I really enjoyed watching. Two years ago I fucked up a very dirty shimano 3 speed hub from my sons bike. I thought, well I can do this! I Watched reassembling videos but at the end it diden't work. Finally I bought a 2nd hand inner work for less and finished the job. Could not sleep for 2 nights, felt very disappointed in my skills. Your video reminds me about that my struggeling moments with the shimano hub. BUT, I really got BIG respect for the engineers who invented these hubs with so much parts, all designed with a purpose and all work together. Me myself, I am am audio/video composer but when I got a BMW R60/5 (1971)from my dad 15 years ago, I started to appriciate the wonderfull world of mechanical enginering. Great Video !!!

[@allseeingotto2912]

Love the old BMWs , I used to have a R100RS , now I have an old R1100GS .

[@AntonBabiy]

I find it amazing how they design these things! So complicated

[@RGV2300]

Indeed, they take epicicloidal gearsets found in automatic transmissions to a bike, i freaked out the first time i saw this.

[@Za7a7aZ]

Gears...thats for autistic avants to design I think. Have you ever seen how they design the gears for watches...with those special challenges..what do they call it again... Anyways...with simulation software it is much more easier to design very complicated small mechanics...

[@wongjock648]

Yes indeed. Crazy skilled Japanese people just going hard on quality engineering and design.

[@PiotrK2022]

Yeah complicated as fuck.... Without knowing assembly procedure there's no chance to get it working back after disassembly.

[@055_rickysuryapranata6]

yet so cheap

[@edriley6739]

the complexity of this hub is a-pawling and your stick-to-it-tive-ness to be applauded. keep at it. get those pawls aworking and astonish us

[@classydays43]

Kudos to whomever designed this thing, but rebuilding one deserves a beer

[@100rogerduncan]

Thanks for the great video. THE PAWLS ARE WORKING FINE! They don't get pulled down! They just get overridden by the shell because it moves faster in higher gears so the lower gear pawls just slide underneath while the correct pawl grips. I think if you tried this hub it would work fine!

[@rewind1961]

Thanks for another great video. I obtained a Nexus hub for just about free but was it frozen and rusted. I took a little apart, and got it shifting, but the pawls would not engage. More disassembly and eventually all working good. Your video was the best on KZbin with careful and clear explanation of the assembly. This was probably the most complicated assembly I have ever performed and would of never got it completed without your detailed video. Thanks, RJ!

[@sitflyer2661]

and they said nobody could put Humpty Dumpty back together again! Well done!

[@brindlebot]

Really appreciated this vid for my Nexus 8 service. More parts than I thought which would have been impossible to put back together without this video.

[@diavalus]

6 months ago, I tried to service the same hub. Guess what, I've had the same issue and I gave up after a while. Anyway, cheers for your effort of putting everything back together!

[@Daniel-uo5lm]

To me it looks like either the tabs on the turning thing that push down the pawls, or the parts of the pawls that get pushed down are worn out, which causes them to stay up too much. I guess the grime and sand that was in there before might've done that damage. Amazing job on reassembly and explaining all the workings of the hub at the end!

[@jackreacher1963]

Thanks for videos on these hubs I now can take them a part and rebuild them no problem.

[@01FozzyS]

Now you're an authorized Shimano IGH mechanic. LOL! Nice job RJ!

[@Francois_Dupont]

actually no, he didnt fix it.

[@ralphievelasquez9985]

Great deal of knowledge... patience and integrity..RJ you are a very smart man.

[@adrianharding1843]

Great video RJ. I was a bike mechanic when I was younger. When one of these things showed up at the shop it really separated the guys that thought they knew (me) from the very very few that did. Your video was a great aid to me while servicing a nexus 8 with lots of drag. Thank you for putting this together.

[@normandgallant8106]

Well done and thanks for your time ......my shimano 8 is still functionning great . The chain fell on the shifting cassette , replaced and all is ok . Replaced cog with a cog with a chain guard , it's needed along with a chain tensionner . I use the nexus 8 on a heavy tandem trike with long chains that are now enclosed in tubes so my chain won't come off on rough roads ....when I opened my hub the grease looked great and I added a bit more shimano grease but my hub did not look like it was oiled . This is the first time I've the oil .

[@SignorLuigi]

That was the most suspenseful video/movie I have ever watched! Will RJ succeed? Will be not? You did it!!! Take a huge bow RJ! That was so interesting. Can't wait for the sequel where you do battle with those stubborn prawls!

[@TopseyKretts]

..Man..that was impressive!......awesome work R.J..

[@johnburton9156]

If anyone can do it RJ definitely can. RJ you're the man love the videos keep them coming

[@dennisolsson3119]

7 speed looks similar, but note that the cog wheel looking plate at 13:30 has an outside and inside and the shift arm will not fit if this plate is turned wrong. That was the case for the 7 gear hub. Thank you for the video! You saved a life today... The life of my wife's bicycle :)

[@MrKfq269]

The inventor of that type of hub is an absolute genius. Its hard to believe that its all for a bicycle wheel.

[@OjStudios]

Not a suprise it costs a small fortune to get one of these fixed at a store. Nice job getting this back together! I know it's not easy, I've done one with 7 gears and it's a real PITA.

[@villetta3705]

Amazing understanding for machinery,mechanism and gadget! There’s no mentor about bicycle mechanism like you in Japan , though SHIMANO is made in our nation Japan😭 Thank you so much indeed. May god bless your hand and soul. Domo Arigatou❗️

[@saqrsalem186]

RJ you are the best as always👍

[@MrBlurry2011]

you where so close, I stumbled on this and got hooked. Never knew these existed, now I can see how they work. Pretty awesome device. Thank you.

[@ligmuhnugs]

This is the best video out there showing one of these gearboxes going together. I have a nexus 7 speed that won't shift to 1st or 2nd gear.

[@slideman.]

What an amazing piece of machinery! Thanks RJ! That's why I keep coming back to watch your videos! great job!

[@storlach]

You, Sir, just saved -well not my live - but my wife's bike! Thank you so much for this perfect video!!

[@davidcollishaw2771]

Blimey this Was a hard video to watch as some of the assembly seemed to run backwards, but I managed it after a service went wrong and I managed to jam it in gear by separating a spring and tab right down deep inside. I've never wound a vid back so much so thank you for this one.

[@SuperJerot]

Last time the word was "here", now it's "little". RJ The Lil Bike Guy. Glad you were up for the challenge for assembling this thing!

[@JohnD666]

Hey RJ, thaks for posting this. The detailed vid just made my day, when i botched 'fixing' a Nexus 8 hub.

[@imawrench]

Well done Dr. Science, I mean RJ. I have a had a couple of these hubs apart, same situation, "something" not functioning properly. Very informative video, thank you for sharing it. Be well, Stephen

[@keithschrack]

My kinda guy! The service manuals for SG-8R20 are available through Sheldon Brown's page, but I'm guessing you already knew that. The axle group (with pawls) appears to be a lowest replaceable assembly.

[@choobv2]

Definitely still useful and all the more interesting because you didn’t contrive a happy ending for us. Real life. In a garage.

[@rajkins2k]

i love how you re did ~min 16 - 19 as your part and demonstration went off-screen in the first part -*Thumbs-up*

[@recstoppauseplay]

Fantastic work RJ! I couldn't stop watching how this transmission (basically what it is) goes back together and how it works. I thought I had the 3 speed Sturmey Archer down then this comes along and .. wow.

[@balloney2175]

You were able to put it back cuz you are the inventor of that.

[@Ricobass0]

looking forward to when you do get it figured out!

[@TheJoePavlik]

Shifting ring part was so cool seeing the guts and pawls move.

[@spinaway]

This just goes to prove the theory that if you can workout how something works you can repair it, well done and thanks for sharing.

[@alexs8941]

Dude you are awesome! I was having the exact same probleme of standing in front of a complete disassembled hub and now i can piggyback of your video.

[@leestimson12]

Absolutely amazing!!! I got thinking while you were working on the hub about the people who designed and engineered that whole mechanism and the mathematics needed and then to make all those little individual parts and...... I'm sticking to just repairing bikes. Much easier. But this was truly fascinating.

[@keeanmorishita8457]

I am amazed at your determination. You have inspired me to take apart one of these Nexus 8 myself! the model I have to try with is one generation newer than the one you have I believe? It is an 8 speed but some of the ring clips seem a bit different. Either way I have had shifting issues such as slipping gears regardless of cable adjustment. Numerous Nexus 8 have had gear 5 fail and I wonder if it has to do with the clutch engagement you showed. Thank you so much RJ. You are my favorite KZbin bike mechanic

[@GordoGambler]

Perfect video RJ, the other Shimano ones are almost all Russian. I now have a Nexus 7i with a nice trigger shifter. Perfect gears for medium hills, city and highway. It came with 44/22T, too slow for me. Now going to try 18T. The stupid roller brake makes it way slower than my finicky shift SA XL-RD5w. This 5w IS the fastest hub I've ever had, done 46 mph on a 8% hill. But I want to tell everyone to not be so afraid of a little play in ANY bearings. The 7i came tight and so did every pedal I ever bought. The 7i coasts way farther now, it was worse than my Rohloff ever was. LOL.

[@RobertRabazzoMeier]

great respect its really unbelievable to get this thing together

[@LauriAP]

Shifter sleeve was the part operating the paws. There is something wrong, Maybe cleaning helps. You found out how to do it, assembling the nexus hub, Congratulations :) !

[@mscir]

Very interesting. I hope you do a video on the next step of diagnosing the pall problem.

[@yasiryw1177]

That was coooooooool These hubs are really cool and a wonderful piece of engineering, it looks like NASA stuff. Thanks man, you Rocks

[@XxXnonameAsDXxX]

Actual madman assembled it back! respect

[@bb1039]

best one so far on how it should work

[@bruceabe3139]

RJ you are a hero!...Standing O for you pal! I've always wanted to take one apart but have no time at the shop. This series of disassemble and re-assemble will come in handy one day. Thanks for sharing your knowledge.

[@tinkerbilletjes]

Hey RJ, thank you so much for this video. Used this together with other sources in order to repair/rebuild my Inter Nexus 4 - because I hadn't taken any pictures.. Unfortunately the hub is still broken although I can't see how/where, but it didn't shift anyway when I got it. Unfortunately also my rear wheel doesn't rotate with the chain any longer. I gave up after having taken the hub apart for the 12th time ;) (I can dismantle/reassemble it in my sleep). Thank you for the detailed videos on bike fixing!

[@tinkerbilletjes]

Got it working to shift to 1 and 4 one time, but the entire thing made and still makes an awful scraping noise when freewheeling...

[@hatsunemikussnzbmindcontro4444]

The parts inside 😮 Its mind blowing! ( And to fix ) 👍🏼 🙋🏼‍♀️

[@oldkins]

Wow, someone has been doing a bit of homework, Chrystal clear instructions RJ. Thank you.

[@MrSlava59]

Большое Вам спасибо. За интересное ! Нужное !И очень понятное !Видео пояснение сборки Shimano Nexus 8 Speed

[@claudiotrentini7567]

16:55 start clip 1 17:50 end clip 1 17:50start clip 2 (is the same clip) 18:34 end clip 2

[@RJTheBikeGuy]

Hehe Editing goof! I saw the first clip had the unit out of frame, so I reshot it, and apparently forgot to remove the first clip. A peek behind the curtain.

[@mrmott44]

Good video. I learned to rebuild these from the Russian video but it’s nice to see another viewpoint

[@rb6951]

Thanks RJ, thanks to your video I was able to repair my bike.

[@thecrew257]

Can I youse cooking oil ass Shimano oil?

[@namdarbolour9890]

At 17:30 I believe the part you call a "ring bearing" is actually a roller clutch (a silent freewheel implemented by those rollers riding up ramps). It is not a bearing, rather a one-way clutch, or freewheel. Great video, thanks.

[@truckertom3323]

There you go see, i knew you would get it done, Genius.

[@marvinmartion1178]

I watched the disassembly and would love to see it back together working! You do have film for reference, so

[@fatihd.1792]

the best bicycle mechanic.

[@BrandtRalf]

Thank you that helped me a lot, when doing a big maintenace on my nexus intr 8 gear hub.

[@hemtet5500]

Wow a very engrossing Sunday afternoon watch the Pawl mech must be examined

[@Pudd27ut]

My god,That circle spring installed:) N8 was revived And my soul too

[@philipmarshall-cox2664]

R.J. I do not thing the pawls staying up is a problem, because you are shifting up the gears, so the hub shell speed relative to the axle is increasing per revolution of the input. As long as the pawls are free to "ratchet" the motion of the shell will not cause any issues. It will just push them down out of the way. I have just rebuilt an SG C 6000 8R and it displays the same behaviour but works fine. Cheers.

[@RJTheBikeGuy]

I don't think they ratchet like that. I think one pawl at a time is supposed to be up and hold one of the three gears inside, basically making it a sungear: kzbin.info/www/bejne/oWnUcqFoeZVoiJo. And the other two gears will turn freely.

[@philipmarshall-cox2664]

@@RJTheBikeGuy The position of the pawls (up/down) is governed by the internal ramps cut into the fingers of the shifter barrel. This is all one part and therefore the relative positions of the pawls is set by the barrel. Unless the barrel is twisted or distorted, it is tricky to see how the relative up/down positions of the pawls can be affected. Given the tiny clearances available within the mechanism, I doubt a distorted barrel would turn at all. I wonder if the pawls are further pulled up as they catch? The slight downward movement of the "used" pawl may give it sufficient clearance to be fully disengaged even if it is not fully retracted. I love these hubs and your videos. They are a delight to ride. The sgc 6000 I mentioned before was junked because it was slipping. That was free and just had gummed up roller clutches fron the incorrect grease. I run ATF in mine and avoid laying the bike over. Works a treat. Cheers. Keep up the good work.

[@100rogerduncan]

You are right. The pawls are working fine. I hope RJ tries the hub because it will probably work. RJ fixed it! (I am NOT being sarcastic). RJ, I would love to hear from you! Roger Duncan.

[@Bikeops2021]

Great work RJ, very clever design work here hope you get it working correctly sometime.

[@danielbursch3605]

Very useful video! I have a Nexus 8 inter8, model number SG-C6000-8R. What I discovered is that I have a needle bearing type of clutch...so I do not have the pawls like other hubs have. I had removed the roller bearing ring and did not put enough tension on the spring when I reassembled it. The symptom I had was that when I shifted to 5th or higher, I could not pedal any longer...it locked up but the wheel kept spinning. I'd attach a photo of what my clutch looks like but I couldn't figure out how to include a photo....Thanks again!

[@MrKatsu93]

I have the same issue, not same model thou. Which spring are you reffering to? General clamping of everything or the collar thingiy with lots of cylinders or maybe something else? Sry, not used to the names of everything 🤣

[@anthonyschmieder3174]

You have the patience of a saint!

[@whatyoudo9773]

Im amazed at all the people praising you like you have accomplished over-unity! You are knowledgable, tenacios and patient but you didnt invent the damn thing! Sheesh people! The wonder here is in the precision and metalurgy of this incredible mechanism which owes its origins to the great thinkers of our past...watchmakers, mathematicians, blacksmiths and those that made weapons of war. All we have to do as careful mechanics is pay attention to how it comes apart then work backwards and have the right tools and dexterity. Man people just love to pat themselves on the back.

[@wodstalker2819]

Re assembly is even more impressive lol, goog job !

[@lingoflamingo622]

Thx, this vid saved my day and my customers hub

[@davepowell1521]

So interesting and very well explained and filmed!👍👍 5 dislikes why??? Your video does what it says on the tin.

[@that70sschwinn]

I found it very interesting and was rooting for it to function once reassembled...nice demonstration just the same.

[@zigzag8111]

I was so sure you'd fixed it.....I was on the edge of my chair while you were winding those spring clips into place too.

[@tonyconnors1342]

Really enjoyable i knew you would make this video someday thank you love watching your videos very educational.

[@Geoffrey150]

Crazy interesting!! Amazing video, thank you!

[@martinberry1040]

Good gracious, what kind of mind invented that mechanism - I mean, someone must have been dreaming about it and got up at 3am and started sketching stuff out. Great attempt at putting it back together, maybe it did not conclude quite how you intended, but what the hell. In the real world, would it be economic to service a hub like that - the number of man hours involved must be quite large. Anyway, it's the sort of thing I would attempt, figuring out how it's working during the process. Good job and thanks for sharing with us.

[@ひーたろ-i6g]

It was very helpful to me. I appreciate it very much.

[@BikeLifePinas]

Interesting and fascinating. Maybe more of these videos soon

[@mitzij]

Amazing video dude!! Simply amazing, just like a mechanical puzzle. I admire you for your patience getting all these parts together.

[@mihalytakacs6512]

Great video,thanks a lot! A note: When you installing the ring gear at 21:07 you must have been timing the planetary gears.Each of the three cog there is a little sign on it.The three sign must be standing in the same position during the ring gear installing. This video show it at 7:20 kzbin.info/www/bejne/sKqoZnSLnbx7has maximum respect

[@zelupl2063]

I wanted to say the same xD. Otherwise the mechanism will get destroyed after couple of spins of crank :/.

[@mrmott44]

Shimano makes a tool to hold the gears in proper timing. Well worth it if you’re doing more than one or two. Also the drifts to set the collar and seals are worth it. I’ve used shimano white igh grease but next time I’m trying some automotive transmission fluid

[@mrmott44]

Also, use regular axle grease on the wheel bearings

[@sterremonstar]

Wauw, super to see, thank you!

[@ZzulfadliNasir]

Thank you thank you and again thank you i wait this video for quite so long on how to overhaul this gear 💋❤️

[@mikeypictures983]

wow.. I am so impressed by your mechanical skill! and also by shimano's tech. thank you for sharing this video!

[@kleberguirado]

Fantastic! Like a Swiss watch. 😁👍

[@endoucheeray7018]

you have to admire how hard shimano is trying to sell their grease....

[@yuukiokazaki3543]

OMG YOU DID IT!!! :D SUCH A LEGEND

[@darrengarvie8832]

Loved this video

[@Michael-wn4jj]

I can feel with you. By misunderstanding I removed the right side nut and disassembled the clutch. It took me hours to get it functional reassembled. My conclusion is never remove the right side nut for maintenance reason. Meanwhile our all season used pedelecs have 14000 km each and I did the 5000 km Shimano oil bath maintenance and greasing on both recently. They are still working fine and switching preceisly. Some say the Nexus has expected lifetime of 20000 to 25000 km. Will see.

[@kenken-ss7jn]

Great work and info

[@daveyJ213]

JR, you are a mechanical god! I was wincing and flinching the entire time, waiting for a spring to come flying thru the computer screen. I can't believe you re-assembled that hub without the proper tools and jigs that I'm sure they have and use at the factory. Additionally you did not even impale a finger. Amazing. Perhaps those pawls work better under some sort of centrifugal force when the bike is in motion. Just a thought. It must be the boy in me, but I love tearing stuff apart to see how it works. Good work.

[@mqqnmypops]

Veeerrr interesting, but... I bet there's some small ramps, and of course springs that have some gunky stuff caked inside that last bit keeping those detents from function properly, you'll probably/undoubtedly have to disassemble (no disassemble) #5 is alive. Great vid 👍 if anyone can RJ, can. I owe u a 🍺🌮😎

[@philmorrow2446]

Excellent and informative. Glad you rose to the challenge! Could it be that the pawls are not meant to be greased? Oiled only?. Just a thought that the grease may be taking too much room in the system and gumming things up.🤔

[@RJTheBikeGuy]

I don't think that is the problem.

[@cspower7259]

Imagine servicing these allday. Haha. Would drive you mad.