Freewheel broke off

520rider · Feb 6, 2012

Hi
I was wandering if this has happened to anyone.
It is 500W 8FUN BPM2 Rear Drive Hub Motor I purchased from bmsbattery. It was about seventh ride on it, never pedaled hard, pretty much always in highest gear and the thread holding the freewheel broke clear off the hub. I tried to post a picture, still don't know how to do it.
Thanks
Frank

ohzee · Feb 6, 2012

not common , but I have read of that happening to others. Sorry to hear that. You get a hold of the manufacturer to see if they can help you out ?

Has to be a defect no human should be able to sheer that off.

adrian_sm · Feb 6, 2012

I have had it happen, but mine was on a Crystalyte 408. I just stood on the pedals taking off from the lights, and suddenly my pedal disappeared from under me. The quality of the casting was pretty poor, that combined with a decent cantilever load from chain forces, and some good stress concentrators due to threads, and a thin section in the cast is what caused it all.

They have since changed the design to have a steel support material, rather than just raw aluminium casting. The company I bought it from organised a new side cover with the updated design at no cost. Hace now riden >10,000kms with no issues.

Contact the company you purchased your motor from, and hopefully they can fix it up.

To post a pic, just scroll down below the area you type in, and there is a tab headed upload attachment. Click on that and it should be obvious from there.

Good luck on getting it fixed.

- Adrian

neptronix · Feb 6, 2012

Wow! that happens with older MAC and BMC motors, but i never heard of a failure with bafang.

If you can find replacement parts for the bafang motors, i would like to hear how. Usually Bafang does not sell replacement parts, so they have not been an option to me for bigger geared motors.

dogman dan · Feb 7, 2012

Hopefully they will at least send you a cover, without you having to send the motor back. I shipped a motor back to china once, and it was quite expensive.

docnjoj · Feb 7, 2012

neptronix said:
Wow! that happens with older MAC and BMC motors, but i never heard of a failure with bafang.

If you can find replacement parts for the bafang motors, i would like to hear how. Usually Bafang does not sell replacement parts, so they have not been an option to me for bigger geared motors.

Hey Nep. John Rob Holmes used to carry gears for Bafangs. Not sure if he still does. Also Keywin used to carry nylon and steel replacement gears for Bafangs.
otherDoc

520rider · Feb 8, 2012

I have couple pictures here.
There are no screws holding the hub covers, is it press on or screwed in?

Haste · Feb 9, 2012

i would like to know this also, as I have the same motor. Mines getting laced this week, and this is just plain scary...............

I think those 4 slots in the side are there for a reason..maybe its threaded?

mxer · Feb 10, 2012

Thanks for posting this, I only just fitted my DNP 11t freewheel yesterday and was thinking to myself there is not alot of support within the extra long tunneling where the axle runs through, so it's putting alot of stress (if peddling hard) on the thread, Pahaps an extra bearing or spacer would be good for support in the tunnel area over the axle?...

I am soooo greatful i have seen this as when i am on the 11t i will not be putting to much pressure peddeling in these higher gears, If i ever have a problem with power from the batteries and have to limp home i will always remember now to use the 34t where there will be less stress on the thread of the hub... Thanks, And good luck with with the fix and remember you have proberly saved alot of threads on hubs by posting this, You have deffinatly saved mine :roll:

miuan · Feb 10, 2012

Guys, if any of you get the exact size of bearing needed to support a DNP 11t freewheel, feel free to let others know. even for motors without the "bug", this can't do any harm...

mxer · Feb 10, 2012

Usually a measurement of ID and OD and a bay search, somthing pop's up, But i have put my wheel back on, I will have a look later..

mxer · Feb 10, 2012

Would be interested to know if 520rider was using an 11t and was hard on it ?

mxer · Feb 10, 2012

I have just ordered two of these 26,17,5mm it's a standard size so it was cheap 99p each, I will need to shim on the id tho, The actual od of the DNP is 26mm and the axle is 14mm i have a shim/ spacer with an od of 17mm 8) :mrgreen:

I post some pic's to see if it is successful...

Haste · Feb 10, 2012

520, any help trying to contact bms about sending a new cover? What irritates me is that they have access to all these parts, but never respond to questions. However if you order something it at your door in less than a week...

520rider · Feb 10, 2012

Hi, I've been using 11T, but I'd say not that hard.
Just got e-mail from BMS, they talked to the factory and will send me parts with instructions next week.

mxer · Feb 11, 2012

I ordered some bearings to give this a go to support the huge unsupported tunneling withing the DNP 11t freewheel, The leverage on the very short hub thread on the motor casing using an 11t must be massive....

The bearing i used is a standard 6803 26x17x5mm and cost 82p of the bay (UK and US) , You will notice the id of the bearing is 17mm, I have a 14mm axle, but due to pure luck already had 14mm id to 17mm od spacers

who cool was that!!!..

Anyways, I think the best bit is you do not need to press the bearing into the frewheel (i was paraniod of getting it off again) it's a snug fit and is easily removed.... I did need to press the bearing on the spacer, which is cool because it then holds the bearing inplace

....

I'm not very good at explaining things so here's some pictures, I personally will not run an 11t DNP without suporting it now, After 520rider bought this to my attention at the top, Hope you get it sorted mate :wink: ....

Unsupported tunneling well over an inch :shock:

Proberly takes it up the freewheels gears by 4 (emagine forces on 11t, If peddling)..

Bearings and spacers i only used one bearing, but could go for two if you like..

Nice fit, keeps the crud out aswell....

Wurly · Feb 11, 2012

That is an excellent idea. I was trying to figure out where you got the 26mm measurement from, but now i see.
I'm guessing you have a lathe? if you made some more shims i would buy a few and i expect others might too.

mxer · Feb 11, 2012

The 26mm is the ID of the freewheel, The bearing's OD is 26 mm so a nice fit

.....

The shim's/spacers i used where already on the motor i bought, so i have no idea where they came from?, But it's only steel tube so shouldn't be to hard to find 14mm ID and 17mm od.

If you have a DNP 11t freewheel, and you would like to have a go at fitting one, I will send you one to have a play with for free as they are really cheap (you will need to source your own shims at the above dims tho) ......

520rider · Feb 11, 2012

Very nice mxer, my freewheel ID is 26.5mm, but I have a small lathe, I could make a shim.
After seeing the post about freewheel cassette made by Bafang, I e-mailed BMS with question about possibility of modifying my hub with this new one.

mxer · Feb 12, 2012

Mine is 26.5 too, There is a nat's of a thou clearance around the bearing which can be tightened up with some insulation tape for a snug fit, Any tighter and you will stuggle getting the freewheel of again :roll:

...

I geniunly hope you get this sorted with BMS, Good luck mate :wink:

Fishmasterdan · Feb 12, 2012

I may have to try that, Good idea. I have broken every geared motor at that area. (BMC,MAC, old original Pumas) .
Here is one that broke this weekend. I am going to get a cro motor and see if they are any better. I am tired of breaking down at every turn. Please let me know if this works out for you.

neptronix · Feb 12, 2012

Geez, what is with all these freewheel side covers taking a dump all at once?

Fishmaster, how old is your MAC motor? there was a point where the freewheel cover was redesigned in the last year and i'm curious how old yours is.

And what the heck happened with the scrape marks all over the freewheel cover? Did you go out of the range of gears, or what? did that contribute to the problem any?

Fishmasterdan · Feb 12, 2012

neptronix said:
Geez, what is with all these freewheel side covers taking a dump all at once?

Fishmaster, how old is your MAC motor? there was a point where the freewheel cover was redesigned in the last year and i'm curious how old yours is.

And what the heck happened with the scrape marks all over the freewheel cover? Did you go out of the range of gears, or what? did that contribute to the problem any?

Well lets see. I broke my first one in 09 so they (the motor manufactures) have had a problem since then anyway.
Mac motor was purchased Jan of 2011 I believe. I would just buy a new one buts is a 5.5 kv special order.
Scrapes are from getting a screwdriver under the freewheel to get a gear puller on it.

neptronix · Feb 12, 2012

OK - just checking. You have freewheel cover revision #2 for the MAC motor.

http://endless-sphere.com/forums/viewtopic.php?f=6&t=25889&start=105

I broke around May 2011 and think that i bought mine right around the same time as your Jan. 2011 one.
I sent the cover plate to MAC and they revised the design again, some time in the middle of 2011.

BTW someone just had their freewheel thread break on a 5303. I am almost wondering if supernatural forces are at play, there are 5-8 broken freewheel covers within the span of 1 week..

John in CR · Feb 13, 2012

Fishmasterdan said:
neptronix said:

Geez, what is with all these freewheel side covers taking a dump all at once?

Fishmaster, how old is your MAC motor? there was a point where the freewheel cover was redesigned in the last year and i'm curious how old yours is.

And what the heck happened with the scrape marks all over the freewheel cover? Did you go out of the range of gears, or what? did that contribute to the problem any?

Click to expand...

Well lets see. I broke my first one in 09 so they (the motor manufactures) have had a problem since then anyway.
Mac motor was purchased Jan of 2011 I believe. I would just buy a new one buts is a 5.5 kv special order.
Scrapes are from getting a screwdriver under the freewheel to get a gear puller on it.

Dan,
Cannibalize an AL BMX rear hub with a thick spoke flange, and get a new one welded on at the spoke flange for a stronger than new solution. For the one with broken cover, just get a new thicker cover turned from AL plate for another better than new solution, though I'd start with welding the old one back together, not a difficult repair.

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