BH / Dapu M155 freehub, parts and maintenance?


Active Member
Hello all!

UPDATE: FREE HUB overhaul. I've now studied how to overhaul the free hub, click here to skip to the updated instructions

UPDATE2: MOTOR ROTOR and main bearings. Finally pulled out the motor to see the planetary gears.

Long story (skip to question below):

I've had my 2015 Evo 29er for about 6 months now, and I've been servicing it myself as I do all my bikes.

I've had no technical problems thus far with over 2200km / 1400mi riding, but yesterday I propped the bike up on the repair stand and started listening to the rear cassette and freehub. It was making a telltale sandy/crunchy noise, and the cassette had some play in it.


I took off the rear wheel, took off the cassette (lock ring), and the freehub was indeed slightly loose. So I took off the locking nuts on the rear axle, used a special tool to open the cone bearing on the end of the freehub, had the usual explosion of tiny (bearing) balls, cleaned them and the freehub body in turpentine solvent, regreased the bearing grooves and reseated the balls, reassembled the b*tch of a thing after many tries of testing which shim (of various thicknesses) to ditch in order to remove the play in the freehub. Success! No more play and crunchy noises, or the very rare but annoying slip of the freehub ratchet pawls.

Now! Question: the freewheel hub body has no manufacturer details, seems somewhat specific to hub motors. Can one buy these freehubs from somewhere? Freehubs are supposed to be throwaway parts, but you can't buy these from your local bike shop. Seems to me, the lower freehub (bearing) balls are in a groove that is on the Dapu motor frame itself, and if the freehub is not serviced in time, can damage the motor frame itself.

UPDATE: no, we can't buy these. You'll have to overhaul it yourself.

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Here's a picture of the freehub pawls and spring. and inner bearing balls in their groove. The bent end on the spring should rest in the notch, and make sure the spring is tight enough before assembling, it's made of pretty malleable metal and the circumference can become too big while you fiddle around.

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I've found bh emotion will answer questions like this. Probably best to start at:
It did take time to get a tech and a response (several days via e-mail).
They do have a 5 year warranty on parts if you registered on line.

UPDATE: Finally pulled out the entire motor to have a look at the planetary gears.

Here are some pictures of removing the motor cover and the entire motor. Some pictures are when the motor was new and not even laced onto a wheel, and others are after ~4500 km (2800 mi) and 1 year of all weather riding.


First carefully remove the hex bolts on the flange of the housing using a hex key, they open counter-clockwise as normal. If they're really seized you might need to apply heat to the bolts or the thread side to melt the threadlock, while applying sensible torque to the hex head at the same time. Might need more hands for this. (When re-assembling, thread them in with your fingers first to avoid stripping the threads.) Then remove the two locknuts with a deep 18mm socket and wrench, one at a time.


Then pop the side cover open by gently pulling on the free hub, you may need to tap the housing or side cover with a rubber or wooden mallet. Be careful with the o-ring that runs on the inside of the lip of the cover, do not pry the cover with sharp tools.


Here, on the inside of the cover, you can see the tips of the screws that hold the freehub assembly, and magnets for the Hall sensor(?).
The sealed bearing that actually holds the weight of the bike and rider on both sides of the hub is seen here. It's a C & U 6902Z type, easily replaceable on this side. Not so on the brake rotor side.


To undo the brake rotor side, you need to remove the rotor, again careful not to strip the threads, then use a spanner and an 18mm cone wrench to open the lock nut. Mind the shims under the nut, and take note of their location and number, one might be stuck onto the underside of the nut so don't lose it. Mine had three.

Since the motor cable has been first threaded through the hole in the axle, then soldered and wrapped in a heat shrunk sleeve, and the opening sealed with silicone sealant, disassembly beyond this point can be DESTRUCTIVE if you're not careful.


^(Brake rotor should be off in this picture)
Now gently lift the metallic cable cone / grommet off the sealed bearing while holding the motor cable snugly onto the axle. The black silicone glue is holding onto it a bit here. There's just barely enough room to wiggle the cable cone along the threaded axle, but don't force it or you'll pull on the cable or cut into it. Notice the spacer between the sealed bearing inner diameter ring and the black axle. This will come out with the axle, leaving the press-fit bearing in place.


^Here I've wiggled the cable cone all the way to the top. Once it's free from the axle you'll be able to unthread it off the cable entirely, past the connector plug.


^Bearing numbers 6904RZ and BOM


^ Drive side cover etc should now be removed so the wiring and windings are exposed. Note the shims on the axle near the small circuit board. They will fall off so remove them and count them. The small green PCB is for the Hall effect sensor, and the magnets on the lid pass infront of the tiny black three legged surface mount sensor (?) to gauge the speed of the wheel.


^ Now by holding the entire wheel securely upright (ie between your knees) , grab both ends of the axle and wiggle the drive side end of the axle gently and pull towards the drive side to work the entire motor out of the non-drive side housing / shell and sealed bearing. Don't let the motor jump out so as to not tug on the cable. The spacer between the sealed bearing and the axle is seen just below the cable entry point. Don't let the greasy motor pick up any dust or sand off the floor or desk.


^Here's non-drive side housing the with the motor pulled out. The ring gear, sealed bearing and brake disc bolt holes are seen. At this point you could replace the sealed bearing by pulling it out of the shell. Note that without the brake rotor bolts (in storage etc), contaminants and water may enter the motor.


^The planet gears are green nylon(?), and there are lock-rings and sealed bearings on their individual axles. There is no information on whether these are replaceable.


^Balancing holes.


^ The spacer is made of two pieces, and the gaps sealed for water ingress with black silicone. This is as far as I got, as I was unable to figure out how to pull the planet gear assembly up and off the sun gear that sits at the center of the axle.


^ To reassemble, I placed a good glob of grease under and between the spacer halves, and added some into the planet gear lockrings since they looked dry-ish. The factory water ingress sealant was black silicone or liquid rubber (The Right Stuff etc), but I was thinking of revisiting this motor, so the grease should do fine.


^Wiggle the motor back in carefully, so the gears locate and the split spacer goes smoothly into the sealed bearing and is flush with the outer surface of the inner ring. More grease under the cable cone and between the sealed bearing.


^Even more grease into the cable entry hole. Place the spacers on top of the cable cone and thread on the nut with sensible force (don't overtighten or you'll risk slipping your tool and rounding the nut). Reattach the drive side cover, cassette and brake rotor.

NOTE: Ideally you don't want any grease on the brake rotor side as you risk glazing the pads over, and that's why Dapu have originally sealed this side with silicone, which also resists any brake cleaner spray etc. But brake discs and pads are cheap, so grease it up and don't spray brake cleaner near the axle!
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That's great! Thanks so much for posting that. By any chance have you gotten down to the gears? I'm hoping they last a very long time, but it's in the back of my mind that's the trade off when buying a geared hub.

Thanks again, that information is big!
My goal was to see the gears, but the brake disc/rotor side of the shell is one solid pot, and to get to the planetary gears, disc side sealed bearing and the one way bearing, you have to thread the cord back in, and pull the innards out the cassette side. It's probably possible to service the motor without cutting the 9 leads in the cord, but it might not be.

It would be interesting to know if BH even intended these motors to be serviced, or just to be throw-away parts.

So far from what I've seen online, noisy or faulty motors have been replaced with entirely new wheels. This is fine under warranty, but expecting customers to dish out $600-700 for new wheels will doom these bikes to scrap when they get to be a few years old.

Dapu are of no help. They do not respond to technical questions, or inquiries of any kind.
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My goal was to see the gears, but the brake disc/rotor side of the shell is one solid pot, and to get to the planetary gears, disc side sealed bearing and the one way bearing, you have to thread the cord back in, and pull the innards out the cassette side. It's probably possible to service the motor without cutting the 9 leads in the cord, but it might not be.

It would be interesting to know if BH even intended these motors to be serviced, or just to be throw-away parts.

So far from what I've seen online, noisy or faulty motors have been replaced with entirely new wheels. This is fine under warranty, but expecting customers to dish out $600-700 for new wheels will doom these bikes to scrap when they get to be a few years old.

Dapu are of no help. They do not respond to technical questions, or inquiries of any kind.
That's just a killer, and it's a very expensive motor. On the Sondors bike, with a geared hub, you can buy the motor for $150, pull out the innards, swap it to the bike and laced rim you have. They say 15 minutes, but I'll bet it's more like 20. You can buy the Bafang gears for $40 or so. Same with the Macs. The Cross Current uses a Bafang geared hub, but I don't know which model. You can kind of see why Bafang is getting pretty strong, as a vendor.

From the New Wheel site:

Good stuff, @Joergen8 Thanks for taking the time to share the pics & description with us. And congrats on correcting the 'crunchy' noises.

Sine you're in Europe, your A to this Q may not mean much + or - to those of us in the States...but what's it like to deal with BH? My impression is that you've taken Q's to them multiple times. Do you a) reach 'real people' with the right technical background, even if you don't get the A's you want to hear...or b) is it mostly banging your head against a deaf wall? Just curious what kind of manufacturer I'll be dealing with when/if buying an Evo. And again, congrats!
I've sent a few e-mails directly to BH in Spain, with various questions, but they've never replied. Dealers from what I've understood, between the lines, is that they have very little communication with BH as well, and it mostly consists of ordering new stock and processing warranty claims. Many dealers are also new to the business, and their capacity to service and learn any "proprietary" bike like BH Evos is not good, especially when detailed service documents are not available. The more standard Bosch and Yamaha systems are well documented and dealers are comfortable servicing them.

I specifically asked my local BH dealer if they can get replacement parts like gears and free hubs for the motors, and first I was told they don't know, and then not to worry, as it's all covered by the warranty. When I insisted on knowing about parts like replacement spokes, gears, rims, I was just told that a new wheel is 600 eur.

Thinking back, I've never gotten any answers. Which is fine, I'll just keep researching and letting everyone know how it is with Easy Motion bikes.

The Dapu M155 seems to be a well made and designed product, and any shortcomings in serviceability is on BH, not Dapu. Dapu is an OEM manufacturer, and doesn't sell to end users. BH either stocks individual parts ready to ship out to dealers, or doesn't.

If any BH representative should be reading these, here's a list of burning questions related to the wheel we need answering:

-Dapu M155 (or other), planetary gears, available?
-M155 service manual, expolded view and schematics available?
-13G (2,3mm) spokes available from BH?
-Alex DM18 rims in black, available?
-Motor shell, o-rings, bolts, bearings available?
-Free hub assembly or motor lid/cover available?
-Motor cable and connector, available?
-Axle locknuts, shims, cable threading cone/cap, torque sensor dropout slug/nut available?

When you consider, that you can find exploded views and full parts lists for almost any brand name power tool online, or walk into a specialist shop and have them order any parts you need, having no schematics or information on what is essentially a glorified $3000-5000 power tool fused with a bicycle, is just plain bad business.
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Thanks, @Joergen8 . I'm now planning a multi-day visit to a dealer with a large ebike inventory in early June. It will be interesting to learn just what they might capable of in supporting a distant customer. Asking a customer to rely on the dealer network - even if some are well-established & experienced - in the one reason why we hear so much about building up a standard bike into an ebike, I suspect. It's certainly why I considered it. And why forums (fora?) like this one are so valuable.
Hello Jeorgen8

Well it seems we who have BH bikes are in for a few problems down the road. Right now, I have my rear off and ready for service.

It's a (BH) Neo Volt Sport Lite "folding bike" and a real great little bike BUT, as you mentioned I too started listening to the rear cassette and freehub and as yours, it was making a sandy/crunchy noise after a wash now thinking that dirt got in behind the freehub bearings causing that noise. The cassette itself was tight with no play whatsoever.

I live in Vancouver British Columbia Canada and I just cannot get any help from anyone here including the dealer which I bought from 3 years ago! Anyway, please look at the photo below where it shows the "2-notches" in the the freehub, for the life of me, I cannot get this freehub off and as stated, I'm getting a run-around here with great frustration.

You mentioned that you used a "special tool", could that tool be like a "VAR 2-Notch Freewheel Remover Tool"? One bike shop I went to, these young bike mechanics dudes all think everyone is stupid on this planet and you can't get a straight answer out of any of them! Just the other day, this guy at one bike shop told me that the freehub is "pressed in" WHAT??? Then he went on to say that I need to replace the whole motor....WHA' DAA....??? This is ridiculous, all I want to know is how to simply remove that lousy freehub, of course then he added that he CAN remove the freehub for me, but refused to do it unless I had a replacement part.....I think this kid was on drugs or something!

From the pics below, you can see the "2-notches" in the freehub. The outer dimension of the 2-teeth is 28mm and the inner dimensions between the 2-teeth is 24.5mm. If this is the tool that I need, can you please verify exactly how did you manage to remove your freehub? All I want to do is get in there, wash out the bearings, re-grease it and get on my way.


BH Easy Motion Neo Volt Sport Lite EN265.jpg

This is my rear wheel and as you can see, BH in Spain has this very special tool, a 10-tooth socket-type of tool that fits over and unscrews the motor face-plate exposing the insides.

This shows where this 10-tooth large socket-type tool fits for disassembly of the motor face.

IMG -BH Hub Tool.JPG


VAR Freewheel Remover-old style Shimano.JPG
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Sorry to hear you (and us all) being left helpless with an expensive product one would expect to get decent support for.

Me and KeiKei (another user here on the forum) have been researching the Dapu freehub, and he recons this tool "SuperB TB-1018" is the one to open the cone bearing. I made a similar one from a large socket by welding rods/teeth on it. KeiKei made one by grinding a socket.

He found these videos on generic freehubs:

So the cone bearing is loosened clockwise, a left-handed thread.

My new motor also had a slightly loose free hub shell that rocks/tilts relative to the motor body even when the cassette locknut is tight. It could use opening and retightening, perhaps getting rid of one shim like I did with my first motor (which is tight still after 4500km).

If I did it now, I'd remove the entire free hub assembly by unscrewing the smaller plate from the motor, and assemble the free hub upside down, instead of hunching over a tipped wheel for two hours. This is of course different on the Neo TDCM motor.

Here seems to be a video on the TDCM hub. Too bad the video is poor quality and the guy's hand blocks a lot of it. At least BH tried to show us at some point.

On the TDCM, the outer free hub bearing seems to be a sealed bearing, and he drills into it to make one ball come out of the race, then uses a puller to yank the bearing out. This only fixes the outer bearing though. And these two bearings are just for the free hub/cassette, and bear none of the weight, just allow spinning the cassette in relation to the hub when free wheeling. The actual motor axle bearings would be inside the motor shell. The TDCM free hub seems a tad overbuilt.
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Thank-you very much for replying back Jeorgen and especially the info on this "SuperB TB-1018" tool. I have researched and found the exact YT videos that you have displayed above, thank-you for them.

Now can you please tell me that by using this SuperB 2-tooth tool and unscrewing the "left-hand" tread, you mentioned that this will "open the cone bearing", this of course is the visual "sealed outer bearing".

So by me unscrewing this outer 2-tooth Freehub ring:

(A) - Will the outer sealed bearing just pop out?

(B) - Or does it have to be destroyed to remove it like in the YT video?
(C) - By using this special notched tool, once it is unscrewed and the bearing removed, will the Freehub then easily be removed off the axle altogether so we can
clean, inspect, lube, and reinstall the Freehub back on the axle?
(D) - If and when the Freehub wears out, can we buy a replacement?
(E) - If and when this Freehub needs replacement, is there a known upgrade to a better Freehub?
(I was "told" that was possible, can't get a straight answer from any bike shop!)

You know, this is not leaving a very good taste......this is a great bike, but it seems that this micky-mouse Freehub design that a company like BH and being 100 years old has got the whole world duped! I just don't get it! I've been to bike stores where they sell these BH bikes and talking to them it's almost like some sort of secrets going on behind back doors for service.....I just do not understand this type of lacky monkey-business that's setup with BH.

If you can kindly confirm the six questions above please Jeorgen? I really need to know before I proceed because once I get this tool and service this lousy Freehub design, I just hope this will not turn into a stuck nightmare where I am right this minute!

The bike's upside down right now, rear wheel axle dug right in, but that's it....STUCK.....and I need to remove this Freehub business, so any and all you helpfulness is fully appreciated, THANK-YOU VERY MUCH Jeorgen.


Now can you please tell me that by using this SuperB 2-tooth tool and unscrewing the "left-hand" tread, you mentioned that this will "open the cone bearing", this of course is the visual "sealed outer bearing".

So by me unscrewing this outer 2-tooth Freehub ring:

(A) - Will the outer sealed bearing just pop out?

We haven't confirmed if this tool even works for the Dapu free hub yet, so please don't go ordering expensive tools yet. Maybe go to a shop and ask them to kindly try a few of theirs to see which size you've got, or ask the online seller for accurate measurements.

I've no experience with the TDCM hub mind you (if that's what you have), but if the part with the notches is like on the Dapu free wheel, then it's the cone that screws the two parts (core and shell) of the free hub body together as a solid piece (and is also the cone with race for a race and bearing ball type serviceable bearing). So it might act as a self-pulling bearing puller too in your version. Who knows! In the video, they yanked the bearing out of the "cone" or lockring. The axle itself shouldn't be tight at all on the inside surface/ring of the bearing.

(B) - Or does it have to be destroyed to remove it like in the YT video?

If the "cone" acts as a puller, and the sealed bearing comes out with it, you'll then be able to knock it out easily since the axle will be out of the way. It'll just be a threaded lockring type part, with the bearing inside it and a hole for the axle.

Sealed bearings are a dime a dozen, so sourcing those should be easy. Just don't damage the machined parts (hub motor body, free hub cone, core) those are custom parts.

(C) - By using this special notched tool, once it is unscrewed and the bearing removed, will the Freehub then easily be removed off the axle altogether so we can
clean, inspect, lube, and reinstall the Freehub back on the axle?

Yes, that notched cone/lockring holds the shell and free hub core together. On the Dapu, the outer and inner bearing balls and races, as well as the pawls will then be accessible. Here we don't know if the inner bearing is sealed too.

(D) - If and when the Freehub wears out, can we buy a replacement?

It looks like a totally custom machined part, so no. Luckily with sealed bearings there's no races to wear out from poor maintenance, so the machined parts should last forever.

(E) - If and when this Freehub needs replacement, is there a known upgrade to a better Freehub(I was "told" that was possible, can't get a straight answer from any bike shop!)[/COLOR][/COLOR]

Can't see how there could be, it's custom made to fit the hub motor body. Only the motor manufacturer could sell you or BH new parts.
Very nice Jeorgen....BIG HELP

I just contacted a really good and reputable bike shop here and the technicians are pros and don't have that "punk attitude" He called me back and said they can get it for $10 CAD, so that's not bad at all. He also suggested like what you did that I make sure on the actual dimensions.

So basically as you're suggesting, I won't know anything with what's happening inside this freehub until I tear it isn't that the wackiest setup by BH? This is nuts man! How long will it take for people who buy these BH bikes to figure this ironic maintenance situation, I mean wow, BH is gonna be down for one big surprise one day.....and like yourself, us guys know the how-to's on cycles and these wacked out BH designs is BAD BAD NEWS.

When viewing my outer bearing you can clearly see that sealed bearing and hopefully, as you said, "as a possible self-pulling bearing puller type version".....I won't know until the 2-tooth "lockring" is unscrewed.

Can you please tell me how did you identify the freehubs you've mentioned.....TDCM & Dapu freehubs, is there a stamping somewhere because I don't see anything on mine?

The part that really concerns me though is the inner bearings! I really think that an actual ball-bearing is set in a cup & cone design and why I think that, is because as you had mentioned initially, I too got that serious "sandy/crunchy" noise coming out of the freehub.....and get this, it all happened immediately after washing the bike, so-ooo what that tells me if the inner bearing assembly is a sealed style bearing with dust covers, then I can't really see how easily the dirt got in! That simply indicates to me the conventional ball/cup/cone in lube setup.....scary, because if the inner core of the freehub was machined to accommodate an inner race design, then we are in trouble because eventually that inner race will just eat it self up! NOT GOOD, NOT GOOD AT ALL FRIENDS.

Anyway, let me take the next step by pursuing the actual measurement of the tool, then I'll go from there and will definitely post replies and pics back to you.

Thank-you again Jeorgen and have a great day
HI Joergen

Check out this "RJ the Bike Guy" YouTube video. Here he's doing a swap from an older Shimano Uniglide to a modern Hyperglide Freehub assembly. Great clues on the disassembly process.

Notice when he uses his 2-tooth "cone removal" tool, this seems to be exactly the process I'll be facing except for the fact as previously mentioned that when I go to unscrew that ring that's seating the sealed outer bearing, I would definitely now imagine that as it's coming out, it then should naturally "pull" the sealed outer bearing with it and this very specific left-hand threaded ring should also be a "cone" on the underside of itself holding the inner center ball bearings as shown. Once removed and as shown in this video, it hopefully should then expose all the inner balls/cups/cones in the main core of the Freehub.

The really cool thing that I am now seeing from this video is that first of all, my Freehub is an 8-speed and get this, it looks EXACTLY like the one RJ the Bike Guy uses in this video and if so, then clearly the only thing that BH has done then is simply modify to their specifications the outer sealed bearing seating within this 2-tooth notch ring that should fit every Shimano Hyperglide 8-speed Freehub!

If that's hopefully my case then....BINGO....I can easily get any Shimano Hyperglide outer and inner core and shell that includes all the main inner balls/cups/cones making it a breeze should I ever encounter a completely chewed up inner core assembly. The only difference would be to reuse the BH specific outer left-hand threaded cone-ring in question here.

From what I see in this video, I think I'm almost absolutely sure that this is what I will be encountering.........again,

Please take a closer look at my Shimano Freehub and you will see that it's exactly like the one that RJ disassembles in his video.

Being the weekend and I have to wait for two separate bike parts suppliers to answer my email that concerns the actual sizing of that Super-B Freehub tool. If my evaluation is correct then that will REALLY solve my problem with that funky BH design that has turned into a weird mystery which I hope to completely solve.

Stay tuned because when I do get this tool and hopefully some time during next week, I will totally fill you in with the details, the procedure along with closeup photos.

Thank again for all your input Jeorgen

Take a look at this very gritty YT video below of this BH technician in Spain when he removes the actual brushless motor cover which is all part of the cassette axle assembly. This brushless Easy-Motion motor is the actual one that I have on my bike. When he finally removes the motor plate with this very specific large 10-tooth tool, you can then see how easily he just pokes out the outer sealed bearing from the underside. With a closer look, you can then see a shiny seat of this problematic 2-tooth outer ring that holds the sealed outer bearing in place.


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Updated free hub overhaul guide: Since I have two motors and rear wheels, one of them just sitting in the corner, I thought I'd revisit the Dapu free hub overhaul procedure.

The magnets will suck them up and you'll never get them out.

Step 1.
To make cleaning and reassembling the free hub easier, let's just lift the whole thing off the motor housing. To do this, we need to unscrew the two locknuts on the axle. Use an 18mm cone wrench or a long socket to do this. Hold the axle with a wrench on one end and unscrew the nuts one at a time. Take note of the number of shims underneath, if there are any, and set them aside. I prefer to put everything in a mineral turpentine bath.



Step 2. Now loosen the cone nut that has two notches in it. You may need a special cone nut socket for this, but I was able to use just a pair of angled pliers and slightly tapping one jaw of the pliers in the clockwise direction (left-handed thread) to loosen the cone nut. Don't unscrew it, just get it loose and back to finger tightness so you don't have to do this in Step 5. (Note: user @KeiKei reports that the SuperB TB-1018 cone nut/crown race tool works a charm for this application. So any tool with similar dimensions should work).




Step 3. By removing the smaller Allen machine bolts near the free hub body, you can lift the free hub out of the motor housing. Find the correct size hex key, clean the hex holes if the key doesn't seem to fit all the way. Find a rod or punch tool to lightly tap the hex bolts before trying to open them (see optional Step 21 below). Keep tapping if they feel like they won't come loose with sensible force. You can easily strip the bolt holes with too much force!


Step 4. Lift the free hub assembly out of the motor shell by twisting it against the pawls (ratchets) and wiggling it while pulling it out. Only an O-ring between this part and the motor housing / lid is holding it in at this point.


Step 5. With the entire free hub assembly now in hand, you can try to unscrew the cone nut by rotating it with a hex key tip or similar small tool, clockwise as before. Do this on the floor or over a pan or tray, as some of the the bearings will fall out, and the free hub core will separate from the shell (splined part) and cone nut. The actual load bearing sealed bearing is on the bottom of the free hub core (inside the motor housing), and a third free hub bearing is a sealed bearing on the inside of the cone nut. This shouldn't need servicing, but you can pull it out at this point and replace it with any matching sealed bearing . Do not apply solvents or excessive cleaners on the sealed bearings, just lightly clean the exterior and remember to apply grease before assembly.






Step 6. Make note of the number of shims and their order underneath the cone nut. This stack determines the tightness of the free hub (how much the cone is allowed to press down on the bearings), and you might want to get rid of one of the thinnest ones if your free hub was loose and had some play in it.


Step 7. Drop all the ball bearings into a solvent bath (turpentine, gasoline etc.), and clean the pawls, ball bearing races and inside of the shell and ratchet teeth with towels tipped in a solvent. Do not spray the sealed bearings with a brake cleaner or immerse them in a solvent, this can dry them out and ruin them. Add only a thin coat of grease to the pawls, as they need room to operate and thick grease may prevent this. Make sure the bent end of the spring is in the notch meant for it, and that the pawls are oriented and seated correctly.

Step 8. Apply grease to the races, a grease gun helps this step immensely. Shake the cup of solvent bath you had your ball bearings in, and seat the cleaned ball bearings in the races with tweezers, first dropping the balls onto a towel and drying the solvent. There should be 27 balls on the inner (lower) race nearest to the motor housing shown here, and 26 on the outer race (inside the splined shell). The bearings are ~3.11mm in diameter, which is a common size in many standard free hubs, and you can salvage bearings from old ones should you misplace one or two in this step.





Step 9. Reassemble the free hub body. Now this is the most difficult part, and you need enough grease to hold the bearings in their races, and might need to repeat this and Step 8 a few times. Place the shims onto the free hub core axle in the right order (thickest one with a slight cut beneath). Put the cone nut into the top of the shell, and look inside to see if the bearings are still in place. Keep holding the cone nut in, and position the core of the free hub into the shell carefully, turning it slightly so the pawls will be compressed and the shell and ratchet teeth can slip past them. Don't force the pawls or they will jump out of their seats, or the spring will come out of its groove. Now, hold the parts together with the tips of your fingers and carefully turn the cone nut with a hex key or other, counter-clockwise to screw the free hub core and shell together. Tighten the cone nut with your special two tooth socket or pliers. It doesn't need to be very tight at all since the thin lock nuts on the axle will hold it together too. Rotate the free hub and listen to the pawls ratcheting (should make a decent noise) and feel if the bearings are smooth. Try to turn against the pawls a few times to see that they hold and don't slip. If the cone wont screw in, or the free hub feels loose or wrong, one or more balls fell out of their race, and you need to re-do this part.


Step 10. Clean the O-ring (motor housing cover side) and the inner side of the free hub core (that holds the load bearing sealed cartridge bearing) and the inset pit on the motor housing cover where it sits, if it has sand in it, and re-grease with a light coat of grease or oil. Greasing it will help seal water out, and it did come greased from the factory. Push the free hub back into the motor housing, turning it as you go to avoid tweaking the O-ring. This shouldn't need any force when lubed correctly. Clean any dried Loctite from the ends of each M4 hex bolt thread with your fingernail, add a drop of grease on each near the tip, and carefully** thread them in.

**Caution: when screwing in any of the bolts, if they want to start off skewed, stop, clean the tip-end of the thread again. Should the bolt start squeaking or feeling really tight even with grease, STOP, and unscrew it. You'll then need to see optional Step 23 to move forward.

Step 11. Add the shims on top the free hub sealed bearing, add some grease underneath to seal the end of the axle. Screw in the lock nuts one by one, to a sensible tightness. Grease up the gap between the free hub shell and the lock nuts to keep water and dirt out.


Step 12. Don't forget (or lose) the small lug on the end of your axle, on top of the lock nuts and cassette, that indexes the torque sensor dropout slot. Seen (poorly) above the solvent bath in Step 1.


Extra: user @KeiKei successfully did this overhaul for his BH Evo Big Bud Pro rear wheel, and took more pictures. They can be found here:
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Optional steps:

Step 21. Using a rod punch tool to tap at the Allen bolts before trying to unscrew them. If they're really tight you might need to heat up the bolts with a heat gun or small torch. This will save you a lot of grief. Third hand optional. Use this method to open the larger hex bolts for the drive side lid of the motor housing, if you cannot get the free hub assembly (core) to lift out easily due to a tight O-ring or the axle being in the way.


Step 22. Then pop the side cover / lid open by gently pulling on the free hub, you may need to tap the housing or side cover with a rubber or wooden mallet. Be careful with the o-ring that runs on the inside of the lip of the cover, do not pry the cover with sharp tools. Just use your fingernails to pry between the side cover and the motor housing.


Step 23. Should any of the (smaller) hex bolts feel tight and start to seize (squeak), you'll need to back off immediately, and use an M4 (machine screw) tap to clean the bolt thread, and the bolt with an M4 die. To prevent metal burrs from falling into the motor, you'll need to get the drive-side lid off the motor housing (Step 21-22). You might not have an M4 tap/die handy, but they cost very little. Do not ignore this step, or you'll risk stripping the bolt hole, and potentially damaging a part that you cannot buy (the motor and wheel costs over $500).

First, look at the M4 bolt carefully to see if its threads are deformed. Form it lightly with an M4 die. It's stainless steel, so this might not work too well especially with a worn out die. Try the bolt in the hole, if it still starts off skewed or feels at all tight, proceed to tapping.

Now use the M4 tap from the inside of the lid to start it off with nice clean threads. Use a drop of oil to prevent seizing or breaking the tap. Go through a couple times until the tap turns nicely.

Screw the problematic M4 bolt back in with a drop of grease. Do not over tighten.

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wow joergen, hope i never need to pay someone to do this on my easy motion bike but what a great and detailed write up

Thanks for taking the time to do all this , excellent info
Great Post Jeorgen

Obviously looking at your Dapu Freehub which has those 6 Hex-Head screws all built into the inside core of your Freehub is different when it comes to mine as you can see in the image below and as shown on that BH NEO e-bikes YouTube video


This is exactly my setup and you can see the 10 "dog-teeth" for unscrewing the motor plate off the axle which requires that very special tool shaped like a large socket slipped over entirely then twisted off. Sure is strange how it was just decided to make it that much more difficult to remove the entire faceplate easily such as in your case with the Hex-Screws and in my case, I'd need that very special large socket-shaped dog-tooth tool as in the video.

IMG -BH Hub Tool.JPG

.......and thank you for precaution of being very careful not to have any ball-bearings escape into the motor, but since mine is different from your Dapu hub and my brushless motor faceplate completely conceals the inner motor, then I cannot see a problem as I lift the outer freehub shell off the inner core, would you agreed to that claim Jeorgen?

The outer bearing measurements you show are exactly what I have and my outer bearing cone is tight! I tried to loosen it (left-hand) but obviously I need that Super-B TB-1018 tool which I will getting an answer from a bike dealer about the exact outer tooth measurements within a few days.

When I'm ready to go, I'll post a similar detailed visual maintenance procedure as you have done here Jeorgen, I think owners of BH e-bikes are definitely going to benefit from our labours here.

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