139QMB Gearbox Bearing Replacement Part 1 (GY6 50cc Scooter)
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- Опубликовано: 15 янв 2025
- Part 1 (of 2) showing the replacement of the gearbox, aka final drive transmission, bearings in a 139QMB / GY6 50cc scooter. Part one covers disassembly and removal of the bearings. Part 2 covers installation and reassembly.
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Part 2 :
• 139QMB Gearbox Bearing...
The scooter is a 2013 TaoTao ATM50-A1.
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#139QMBRepair #ScooterFix #49ccScoot
When he freeze frames and provides the mm's of the bearings and the bearing Part Numbers, it's spot on. I've searched and found all the bearings I needed to complete my crank case bearing replacement project with his information; and the steps provided. Great video for this crank case bearing job. I'm working on a TaoTao 50cc QMB139.
Thanks a lot. You saved me. Hi from Romania.
thank you for making this video. i today i just got done ordering all NSK bearings for my taotao 49cc. i also ordered the honda part number bearing as well. i am having all my bearings be NSK. i am doing a total engine upgrade. bye bye chinese parts and hello high quality parts. i also ordered new gasket and seals. again thank you for doing this video.
Send info
Perfect video !! Precisely what i was looking for bravo 👏
Thanks for the tutorial. It's beneficial!
90, your 2 videos on this are so concise and clear, thanks so much for putting these up. I have a problem with the primary driveshaft on my FIDDLE 1 50 2T AC 03-08 FA05U scooter. It has significant play / movement and it is vibrating the clutch and rear pully above 20 kmph to the point that it is not rideable. It seems like a daunting task, but i'd like to have a crack at switching the bearing and seals myself. Is it possible to show you a clip and a few pics of what is going on? It's really hard to find good advice on this without paying a mechanic a small fortune.
I'll look if you post a vid on youtube and give me the link, or join the forum and there are a bunch of us scooter nuts that are willing to try to help. 49ccscoot.com
Great, i'll join the forum and get the post up asap :)
It's posted under the title - SYM 50 Primary Driveshaft Noise and Vibration. Thanks.
What size countershaft spacer does it use? I can't find one specifically for it anywhere. Thanks
I don't have one sitting around to tell you. I'd guess it would be like the Kymco Agility, which lists part 90429-KNBN-901. Looking that up, I found a site listing it as 1.5 x 12.2 x 20.2 (mm) .
This will def help qith my gear swap
The main part missing would be pressing the countershaft assembly apart and back together unless you're using a Naraku kit that doesn't require that. Taking a look at the processes used, you can get an idea of how you may make it easier though.
If you don't want to invest in a slide hammer, there's tricks to force the bearings out using hydraulic power with grease, bread or wet paper towels. I used wet toilet paper. The smaller bearings were tough, but the larger one came out like butter.
i just had to replace my gearbox on my 150cc, basically the same, but larger, somehow with a good gasket, water got in and all the gear oil leaked out, as a result, all the gears were rusted out and caused my bearings to explode, glad i had an extra bad 150 motor with a excellent gear box laying about...
Permatex Ultra Grey and ThreeBond will seal most up tight if you have issues with just a dry gasket.
i hope that you didn't use them poor quality chinese bearings out of that other gearbox and instead that you bough high quality bearings like NSK.i hope that you listened to 90GTVert in his video.
Is there a 139qmb performance bearing kit?
What is the round peg next to drain plug mine is just a hole and oil leaks out is it a breather thanks Mike
It's an overflow.
@@49ccscoot does it need to be blocked like the one you have thanks Mike
@@michaeldevitt5316 It should not be blocked. Mine isn't. It came with the plastic piece that directs the overflow away from the case a bit so it doesn't run down the case.
Nice video, I will use these steps to swap transmission final output drive shaft.
The shaft with my engine is too long.
+KESEDTUBE Thanks. The steps here should be of use for your project. Might as well check the bearings while you're in there. Good luck with it.
On a 150cc what's the best gears to put in the transmission to keep from redlining all the time
What kind of gear oil is recommend for these 139QMB engines?
Seems like a lot of the manufacturers specify 10W40 motor oil. I always use gear oil in all of my scoots. Mobil 1 75W90 is what I use. The viscosity sounds way off, but they're actually very close because of rating differences. I prefer to have oil in there designed as a gear oil. It's probably fine either way.
The odd size bearing I have found 6303x3-2 says it's a 2 sided sealed bearing with grease inside. Can I use this as it is or do I need to remove both seals to make it an open bearing. Thanks
I use them as the manufacturer of the scooter originally set up the gearbox, so I remove the seals. It's not that hard to do. I somewhat commonly will buy sealed bearings when they're much cheaper than what I can get open versions for and then take out the seals and clean the grease out.
I bought a bearing puller just for this job those bearing don’t budge!!!wtf? Any help? Or ideas? How about heat?
Use heat and the bearing puller. Sometimes I can't get them to come out with a puller alone. There are also other ideas that cost next to nothing that sometimes work. You can pack bread or grease in behind the bearings and push them out that way. Search it here and you'll see examples.
Is the gearset cross compatible with the 125cc version?
I don't believe it is.
Are the sizes the same as the 1e40qmb?
No. 49ccscoot.proboards.com/thread/6145/minarelli-clone-bearings-seals-torque
I recently picked up a new (used) 139qmb long case scooter and it is pretty rough throughout acceleration. Rougher than any other scooter from the handful I've owned. I changed the gear oil and there was quite a bit of metal in the stuff that came out so I'm betting my problem is in there.. was gonna tear into it tomorrow but do you have any thoughts on what I might be dealing with? The best I can describe it is a vibration beginning once it starts moving.. it seems worse during lower speeds and smooths out as I approach cruising speed.
It's a taotao thunder that was pretty well abused and crashed pretty hard at one point.. hard enough to bend the tree a little. Ive already done a top end rebuild with a 47mm jug, new head, a9 cam, stuck a new carb on as it Still had the sealed stock POS and ditched the airbox for a pod.. PAIR system removed and new lines installed as well. Original cylinder still looks great and oil was clean. My atm50 was stolen so I picked this one up cheap and it's turning out to be more of a project than but that's life lol. The speedometer/odometer wasn't working either.. the "wings" driven by the front wheel were bent and no longer making contact. Blows my mind that people can let their ride get so shitty!
Could be bad bearings or wear on the gearing. Could be something bent. Hard to know without looking.
90GTVert of course. I guess ill find out tomorrow. Im checking out another one next week as a parts bike.. if it checks out, I should be able to make one nice and one "running" machine between them lol.. I'm still hoping my atm50 turns up eventually. It was burning oil so unless it's topped off, it should run dry and blow itself up within 100 miles. With any luck, This will happen and the theif will ditch it.
Should the bearings be C3 class or standard? I found only C3 on a scooter perts shop.
I normally use a standard bearing, but if C3 is all that can be found it should be OK.
@@49ccscoot Thanks man :)
Hi would this be similar process for pcx 150
I have no experience with the PCX, but most scooter gearboxes are fairly similar.
Where do you find the bearings or sizes
They're all listed in the video.
You said the gearbox is made of aluminum, but i'm asking, after several changes of the bearings, did the diameter of the bearings seats will be more large and cause the bearing fit too easy ?
They can wear over time just from use. I had to shim one recently in my two-stroke that was off by around 0.001".
i also ordered a rear racing clutch for my taotao gy6 49cc. there is one big problem with it,, made in china and i am now wanting to replace the bearings on it with NSK bearings before i install that clutch on my taotao. do you have a video that explains how to replace out the bearings on the rear clutch.
Check this out : ruclips.net/video/2f-7Q_0GRAI/видео.html
Hi gtvert do they make taller gears for the 139qmb motor? and how many teeth come on the stock final drive gear? thanks
There are multiple gear sets out there for these engines. Stock gearing can vary. Mine are 52/16 and 51/15. More info here at the bottom : 49ccscoot.proboards.com/thread/1265/gearing-database
How often is it necessary to change out the bearings in a gy6?
Honestly not sure. It sounds like a stupid answer, but I'd say when they need it. Mine only has 2,000 miles, but it's had a vibration and both bearings that the countershaft ride in were bad.
Aloha, What number and size bearing is pressed on the drive shaft?
Kevin Sommerfeldt ruclips.net/video/MxIW7Pj_NEI/видео.htmlm31s
Any ideas on hi-performance gears ? how many teeth are the stock one, if you know ?
Check out the last post on this page :
49ccscoot.proboards.com/thread/1265/gearing-database
Awesome video. I have my bearings and seals getting delivered this week for my 1E40QMB. Do you have a comparable tutorial for the short case?
I don't, but it's essentially the same thing as this. Just different bearings and the case opens a different way. The same principles apply for most scoot gearboxes.
Hi my Chinese 50cc has a grating sound from the rear. At 30 mph. Tire spins smooth on stand with some back lash. Brakes release fine. No wheel play . did your counter shaft bearings have any of these symptoms? Also one of my clutch shoe is one third missing. Bearing good. Could thing cause the rough noise? Bill
Mine wasn't noisy. I have had them make noise though. I would check the whole CVT before getting into the gearbox. While the clutch prob should be replaced, if the sound is only at 30MPH, it doesn't seem likely to be the issue. The clutch should be locked in at that point. Knowing it should be replaced, you could just do that and see if it changes though.
The clutch bearings spin smooth. Although the ball bearing was dry. I removed the seal and greased it. The tire back lash is 1/8 inch at the tire bead. The gear lube drained was clear. The drive belt is 15. Mm wide. and loose. New belt. And variator slides on the way ? Bill
@@williamhaskellhaskell3162 That's really narrow for these. Mine was way over-revving by the time it got to 15mm.
So rumbling and whining when decelerating means that the gearbox is bad?
It should definitely be inspected if you're experiencing those symptoms.
What would cause the flywheel to not come off. It rotates freely but the thread on both the flywheel and extractor tool were stripped and the flywheel is still on.
If the flywheel rotates independently of the crank, then I would think something had to be damaged and causing it to hang up. That seems pretty odd.
@@49ccscoot It is driving me crazy. Is it possible the set pin, the bar that goes down the side has torqued and thats what is causing it? I'm worried the flywheel is pulling the shaft through the entire thing. I can send you pictures if you are interested in seeing what is going on.
@@andrewflath658 Seems like it'd be easiest to see with a quick video.
@@49ccscoot That makes sense... on it.
@@49ccscoot ruclips.net/video/_7jbD-6QhPs/видео.html
Whats the name of the tool on removing the bearings inside the gear?
Blind hole bearing puller.
Can you please tell me what that is please
If I want to increase my rear 10 inch tire to 12 inch and keep almost the same acceleration(regardless of top speed) without changing engine,Is there any formula to decide the gear ratio I should change?
You will be better off focusing on the actual diameter or circumference of the tires used. Some 12" tires are pretty close to higher profile 10" tires. I usually just play around with the tire and speed calculators on my site to see how they would change things. www.49ccscoot.com/calculators.html
The goat
I use 80-90w gear oil with just a shot of lucas oil stabilizer, is this ok? I also use lucas oil stabilizer when I do an oil change 29% lucas and 80% senthetic 10w30, is ok?
very nice video~
Thanks!
I have a 150cc quad do you think they will fit
In a 139QMB? No.
That scoot is fuel injected? I see a sensor in exhaust cool.
No. I installed a wideband to make carburetor tuning and maintaining the tune very easy.
Yo man. Just want to know if the bearings are the same sizes of gy6 and mio sporty yamaha? Tnx
I doubt it. You should be able to look up bearing sizes on a manufacturer parts site for the Yamaha.
90GTVert tnx sir. Glad to hear a respone
is it possible to swap rear axles from a 1p39qmb to a 1p39qma
I would think it is, but you should measure what you have and try to
compare to the axle you're looking at. Count splines as well. Some sites
like PartsForScooters are good about listing dimensions. Ebay may also
be a spot to find parts with measurements.
How long can you ride on a noisy rear wheel bearing is it dangerous. My scooter passed a certificate of fitness safety check does that mean they would have checked the rear wheel bearing I'm unsure if it's the bearing I can hear.
Could be dangerous if something fails totally or could be bad if it leaves you stranded or damages other things. Should be taken care of ASAP. Hard to know what was checked unless you got a list. Even then, I've seen lists just checked off without actually examining all parts.
90GTVert can a wheel bearing be bad even if there is no play when i wobble the back wheel to check bearing play. Also Is 10w 40 semi synthetic car engine oil ok for a scooter considering there is no clutch or gears in the engine. I know air cooled engines get hotter but would that oil be ok in a scooter. Thanks
It's possible. That oil is OK. We don't need motorcycle oil for wet clutches. I use car oil in my 4T.
@@matowixunplugged7927 i was wondering the same thing as you about using synthetic car engine oil in my oil crank case for the engine,,, i called the motorbike repair shop Q9 POWERSPORTS in Madison Wi 608 240-9250. they sell Taotao mopeds and they also have their own service center and they are very knowledgable about motorbikes mopeds,, what you use for synthetic oil is motorcycle oil thats wet clutch compatible and no nickel in the oil. i now have been getting from way-mart,,, quick silver power sports lubricants motorcycle 4 stroke oil,,, for use in all four stroke motorcycles and scooters: including sport bikes and duel sport bikes and off road bikes. yes it costs more than car engine synthetic oil but its safer than damaging your engine. i on my Taotao ATM50A1 campus cruiser moped,, i am going to upgrade my license to motorcycle and then i am installing the high performance top of the line 100cc big bore kit along with changing out the crankshaft and connecting rod with a 400 dollar high performance set and high performance carbuator and changing out my CDI and spark plug to high performance and also changing out the variator weights and my final gear drive assembly and also the gear box bearings with high performance and also changing out my rear clutch with a high performance racing clutch. i am also installing a bluetooth stereo sound system on there and also a higher end burglar alarm. i am going to redo my stator from half wave to full wave for more charging capacity. i have also switched out all my lighting with LED lighting. however the headlight runs of AC directly from the stator,, so what i did was i rewired the headlight lighting so i could use a LED headlight,, i rewired the headlight wiring to run off the same DC circuit as the tail light and turn signal DC circuit. i am also going to switch out my lead acid battery out to a moped lithium ion battery which holds a lot more amperage and better CCA cold cranking amps. i have also replaced the moped horn out with a car horn for louder sound.there are a lot of people that admire my motorbike and they love the work that i am doing on it. these Taotao mopeds are chinese motorbikes and in china the stuff they manufacture is of cheap poor quality and thats why i am replacing out all the moving engine parts out with high quality parts. i love my Taotao ATM50A1 moped and thats why i am doing all this work on it.
@@Patty-Ann-Dunn sounds great. My scooter is Korean it's a hyosung beaver 125cc scooter Google it. I still don't see what the motorcycle oil does in a scooter it doesn't have a clutch what was the reason u need to use it ? i know motorcycle engines get hotter because of air cooling but apart from that they are just a 4 stroke engine like a car.
we're did you get the bearings at
+Stephen Lockridge The Honda bearings came from an online Honda dealer. Forget which one now. I just searched the part number and used whoever had them cheapest. The others I got on eBay.
Nice info! very helpfull thanks for that.
I just have one question, when looking for a new sealed bearing by skf, i find 6 models..
W 6004-2RS1 25 euro
6004-2RSH/C3GJN 10 euro
6004-2RSH/C3 6,60 euro
6004-2RSL/C3 5,75 euro
6004-2RSH 6,60 euro
6004-2RSL 5,75 euro
the rs1 model is at least twice as expensive then the other ones, but they all have the same dimensions.
im confused, can you give clarity?
The 2RS means 2 rubber seals. C3 is a clearance. If no C_ is listed, it's standard clearance. Stick with whatever your current bearing is. 1/H/L I don't know. You can try searching SKF's site and they will likely list all specs so you can see what's different.
thanks for your answer dude.
Have a 1983 Honda NU50M (similar tranny setup) and I'm hearing some grinding in what I think is the bearings (had to brace myself up against bike to pull apart drive faces to put in pulley. I don't have much hand strength). I pulled straight out not up or down and it doesn't look like it bent driveshaft. Is is safe to drive hearing the grinding? don't have all the tools to pull this apart. Ideas?
+Mary Hart You may want to start out by draining the gear oil. If it looks like glitter in there, get it apart ASAP. Otherwise, I suppose you can refill it with gear oil and hope for the best. Grinding is telling you there's an issue though, so it's only a matter of time before something fails.
So you said that you're putting better bearings in your GY6 scooter.? What benefits that you get with swapping out the OEM bearings isn't it basically the same benefits as just they will last longer huh.? It was the benefits of swapping out bushings cuz if there's no benefit I'll just keep my OEM bushings in my bike
It's basically trying to have quality parts that may last longer. I wouldn't swap them out if there weren't other issues going on. Stick with stock till it's a problem, but once there is a problem I don't like buying the cheapest Chinese made bearings that I can find if I can avoid it.
I can't say that I've ever had big trouble with the OEM bushings.
@@49ccscoot and yes okay thank you bro for your help I needed this so I'm
more aware of what I need to do with my bike. And yes I understand swapping out parts for Quality Parts I swapped out 99% in my bike of Parts only thing I didn't
swap out was those three things the bushings the bearings in the crankshaft. Maybe when I'm done after my mechanic
finished putting everything on my bike I will upload it on my other channel cuz this channel I'm commenting you on is my music channel and I can show you
everything videos and stuff so you can see the comparisons between my bike
and yours maybe one day we can race our bikes and see which one is faster bro heha.🤣 😉💯
@@marineboy4181 I've never turned down a race. In fact, I almost hit a close friend because he said he wanted to race me on his 150 and then backed down after I got someone to show up to hold a camera for us (before GoPro). That's the only time my friends have ever seen me get angry and some of them have known me more than 30 years. I may enjoy scooter racing too much. lol
@@49ccscoot and you got a deal bro in okay I live in Virginia and my scooter is a 93 CC I got my big boy from Rolling
wrench paid 200 something for it it is performance out to the Max and I'm not mad at you I would have done the exact same thing do you have a passion for
something happens like someone declining your offer to race is understandable you would get mad
anybody would but I'll let you know when I'm ready I'm still working on it bro.
@@marineboy4181 OK, mine's currently just a little 86cc two-stroke and I'm huge so it should be no trouble to leave me behind. Sorry, but the four-stroke just sits in the corner and collects dust/rust at this point till I get back to Project TaoTao one day.
ruclips.net/video/Uj2O2YF8x00/видео.html
nice vide0... by the way, what spray cleaner did y0u use? thanks
I use the chlorinated CRC Brakleen. Any brake parts cleaner should work. Store brand generic stuff works and is cheaper. I use the CRC because I think they make good chemicals and i can usually buy it by the case online for a price similar to buying store brands.
Big like👍🔔
May I have the parts number for those bearings
ruclips.net/video/MxIW7Pj_NEI/видео.html
@@49ccscoot click on link says video unavailable
@@vergelsolis Odd, because it's this video. 4:24 in this vid.
Can you send me website link of the bearings that’s what I need
I buy individually from sites like amazon and eBay and the Honda bearing comes from a Honda dealer or genuine Honda parts site. When buying bearings, just try to get a decent brand rather than the cheapest Chinese stuff that you can find. Brands like SKF, FAG, NTN for example.
what is the top speed now
Didn't change. I didn't change gears, just bearings.
same for a 150?
+Kevin Stearns Most scoot gearboxes will be pretty much like this. Not step by step, but the same basic process.
+90GTVert thanks because the tire how would u say is when u gas it hmm slippin skippin belt ? cvt? hate to tear the rear end apart. 3500 miles. ur the best. u know that.
Full CVT inspection would be my starting point unless you have some reason to suspect damaged gears.
Como puedo aser contesto para con pral una tran misión de esa
I got knowledge to remove a bearing
Damn Ur Good !!!
that's a little plastic washer -spacer i dont know where it was and just install in like on the video 🧐
When i accelerate to a certain speed i hear a sound like whaahwahwahwhawwhoooooooowooowoowo
Gearbox bearings, a tire in need of balancing or something wrong in the CVT like a bent shaft would be my first guesses. Either that or there's an excited elf hiding under your seat.
Save the cost of the blind bearing puller tool for other scooter parts!
Super affordable method: Use wax and a wood dowel: ruclips.net/video/wmfLJ_ZERnQ/видео.html
Candle wax presses blind bearing out when hammer strikes dowel.
Nicholas Cafarelli That's the first I've heard of candle wax, but if you look up pilot bearing removal you'll find similar methods using grease or even a slice of bread.
shiiiiet i don't have the specialist tools. maybe my friend has, but i'm thinking (begrudgingly); motorcycle shop... this is beyond me, i dont even have a workbench, just a toolbox.
You can find alternatives. You can use a breaker bar to remove the wheel nut for example. Instead of a blind hole bearing puller, you can stuff grease or bread in and force the bearings out. Look that one up on RUclips if you're interested.
the brake shoes cant be as that clean come on! you must doing a cleaning before shooting vid.
No prep. I guess that's a pro of a scoot that fails early in it's life and is slow.
did i see an O2 sensor on that 50cc exhaust? !!!!
holly shite,i never knew that....
these GOVs are totally out of their minds,mandating on the emissions of tiny 50ccs!!! damm, when now we all know that the climate histeria was a hoax....
It's an O2, but I installed it as part of a wideband setup to make monitoring the tune simple.
The bearing
I use 80-90w gear oil with just a shot of lucas oil stabilizer, is this ok? I also use lucas oil stabilizer when I do an oil change 29% lucas and 80% senthetic 10w30, is ok?
Sounds alright based on their directions. I've never tried the oil stabilizer before.
Its good stuff