BMC V2 new clutch and rewire

[biohazardman]

Well thought after 4K thought I would share my experience with the BMC V2 speed version. Even with having to replace the side cover bearing every 2K I actually think it's a pretty good motor. I did burn up the controller although that was operator error. After towing my Bob like trailer around with a flat tire, wondered why it felt so squirrelly, for several miles. I towed it up, Powell Butte, a steep half mile plus long hill without pedaling and the controller started acting up immediately afterwards although it lasted for another 5-6 hundred miles before giving up the ghost. I run the motor on 48-52V of a123 and have made many 40 to 50 mile trips to see the sights.

Still the thing seems to slip at high torque levels just when I want the power the most. Installed a new V3 clutch, pictured, upgraded the phase wires and hooked up an Infineon for 60V so the slippage is more noticeable now. Anyone have first hand experience with the motor or hub gear slipping on these? Going to have to tear it open again to figure it out so any info would be good.

Those of you wanting to upgrade the wires on these things might think twice it's a pain. I managed to sneak in an extra 16ga wire for each of the phases but it was not an easy task. Used some extra heat shrink on the end, as others have done, to thread and push/pull the wires through after polishing up the axle hole a bit as the sharp edges catch and tear the shrink tube.

Motor torn down and wires removed. The easy part.

Lots of extra heat shrink to help push/pull the wires through. Some was heated to compact things a bit.

Wires cut stripped and tinned ready for soldering. Sensor wires soldered and glued into place with epoxy.

Some wires soldered and covered.

JB weld used liberally as there is not much space between the cover and wires. Used a greased
sheet metal wrench and some weights to press things down where they needed to be.

 

[neptronix]

slipping clutch at high loads eh.. even with the v3 gearset. Not very encouraging. Starting to think i may go with direct drive even though i heavily dislike the pedal drag and weight.

Perhaps you found a limit. Many have said they are happy with the green gears, but apparently even more improvements need to be made.

 

[nicobie]

Why do you think that the one way clutch is slipping? All they are is a bearing with a ratcheting action. I really can't see how they could slip. It would have to be broken in order to slip and then would just spin in both directions all the time. Think of them as digital devices, they are either on, or off.

I broke one on my 600-s and it made a nasty noise for about 2 seconds and then quit working completely.

That's troubling about the side bearings failing. Did you buy the new ones at a bearing house and ask for a better one, or just get a replacement one from BMC ?

I'm surprised that you could get an Infineon controller to work with the BMC. I tried two different ones and couldn't get them to work worth a damn. They just couldn't control the motor smoothly and probably the reason that my clutch snapped. The new Clite analog one I have works super even at 22s/3p (92v hot).

 

[Miles]

Why do you think that the one way clutch is slipping? All they are is a bearing with a ratcheting action. I really can't see how they could slip. It would have to be broken in order to slip and then would just spin in both directions all the time. Think of them as digital devices, they are either on, or off.

Sprag clutches rely on friction, there is no positive engagement....

 

[nicobie]

Really! Well that blows my argument.

I just went and checked my spare, and sure enough it doesn't click. I wonder why they don't use this type clutch for the bikes freewheel or why they don't use a freewheel in place of a sprag clutch in geared hub motors? Maybe freewheels aren't strong enough?

Thanks for the info.

 

[Fishmasterdan]

There is no clutch?? I am not sure where this clutch is? There is a one way bearing and thats it. It could be the bearing is moving in the case behind the gear cluster (mine did that). The side of the case is aluminum and merely pinched down to keep the bearing in the case from moving. I ended up drilling out the aluminum and replacing with a steel insert.
Mine was a Puma but sounds like same problems.

http://endless-sphere.com/forums/viewtopic.php?f=4&t=8313&hilit=fishmasterdan&start=30

 

[Miles]

There is no clutch?? I am not sure where this clutch is? There is a one way bearing and thats it. It could be the bearing is moving in the case behind the gear cluster (mine did that).

The one-way bearing is a sprag clutch.

Yes, that might well be what's happening, if there's no key. Loctite would fix that.

 

[Miles]

I wonder why they don't use this type clutch for the bikes freewheel or why they don't use a freewheel in place of a sprag clutch in geared hub motors?

Sprag clutches are generally heavier and more expensive to produce, for the same task. They're convenient to use, though. Sprag clutches need to be precision engineered - ratchet clutches can be pretty crude and still work.

Interesting that Shimano has changed from ratchet to sprag clutches in the latest hub gears.

 

[boostjuice]

BMC clutch/freewheel

Sorry to sound anal but the BMC uses a cam/roller-ramp clutch, not a sprag clutch. Both rely on frictional engagement, but are of different design.

The reason why ratchet systems prevail in bicycle freewheel components

http://www.epilogics.com/md/tekintro.htm

 

[neptronix]

so in that graph, lower = suckier? :lol:

 

[Gordo]

BMC clutch/freewheel

Sorry to sound anal but the BMC uses a cam/roller-ramp clutch, not a sprag clutch. Both rely on frictional engagement, but are of different design.


Nothing anal about it. Perfect illustrations.

 

[biohazardman]

Thought there was clutch made to slip to save the gears on the V2, not just the sprag or roller one way, see pics but the V3 is one piece so thinking the motor or the ring gear is what has been slipping from day one. Guess I thought wrong about the clutch thing. Hard to believe it is still running after 4K+ miles if one of them is the culprit as I have not always been kind to the bike and have many off road miles on it. Still it runs fine as long as I am easy on the throttle till I am up to speed.

Got the new bearings at a local bearing supply shop it was Chinese but the original was made in Japan both lasted about the same length of time

Infineon controller is sweet with the BMC it is a newer unit though I know the early ones had some problems with the gear motors fast RPM range.

Guess I will find out what the problem is when I decide to tear it apart again.

Thanks for the info, link and Pics everybody.

 

[Gordo]

"Just pretend that everything is OK maybe no one will notice."
This made me think of many years ago, showing a doctor how to rebuild his Buda Diesel Engine. After a few weeks of evenings, he said to me, "this is nothing like medicine, I give people two aspirins and send them home, they either get better or they get worse. We actually have to do something or this dam thing is exactly as we left it last time we worked on it."

 

[neptronix]

biohazard, what is your experience with riding this motor in the Portland rain?

Mine's been parked inside for a while now.

 

[neptronix]

Ah, i just opened up the MAC motor. quite similar if not identical to the pictures i've seen of the BMC. Has a steel outer gear which is a good thing.. for sure!

I'm noticing that the MAC gear assembly is different than the BMC assembly i received in the mail today. It is lighter and the keyway part moves easier. It also looks like a one piece system instead of a 2 piece like biohazardman's clutch.

http://ebikessf.com/V2-vs-V3-clutch

Here's an article from ebikes SF talking about the clutch slippage..

 

[biohazardman]

Yes I thought slippage so put the V3 upgrade clutch on and beefed up the phase wires while I was at it but in the end I still have the same, what I was thinking was slipping at high torque low speed. The motor runs just fine if I go easy on the throttle till I hit the teens then I can gun it with no ill effects. It's been that way since the beginning 4K+ miles ago. Don't think it is a slippage problem anymore but two controllers have done the same thing. I just received a nice new black V2T with the double 16G phase wires and a better clutch than even the V3 has. I really don't need the 35+ MPH and could use a bit better efficiency and better torque at low speed for the trails. So I am torn as to what I will do. Time will tell.

 

[biohazardman]

biohazard, what is your experience with riding this motor in the Portland rain?

Mine's been parked inside for a while now.

Sorry I missed answering you somehow. I ride no matter the weather and yes in the rain often. Motor does not care I have the wires at a lower point than the axle before they enter it. That is my only precaution. Throttle and batts are out of the weather as you noticed at the Earthday thing.

 

[neptronix]

Hm, that is interesting. Maybe i should worry less about riding in the rain.. thank you for the response.

Anyhow, if you ever want to try your motor out on my cell_man controller, maybe we can figure something out.

I got the programming cable and dicked with it a lot. I cannot get my MAC to stutter or do anything weird no matter what settings i try.
I can only conclude that cell_man has blessed it with the brand of magic smoke necessary for these geared motors.

BMC/MAC guys are having problems with ebike.ca and lyen controllers too.
I heard some odd shenzen controller works.

Would be nice if someone figured this out by now eh.. only been what.. 5 years?

 

[biohazardman]

I have the programming cable for the Lyen Infineon also but have not messed with it. Maybe when I am feeling better in a year or two? It is difficult to remove my controller, due to the few connectors I used, and really not something I want to do unless I have to. Leaving things as they are just limits my acceleration from a stop a bit so probly not such a bad thing. Maybe I will have to fix it someday once the addiction is in full bloom. ;^) Chased a car down the road at 35 today going to lunch. He was the only one on that road so I was safe. ;^)

 

[dnmun]

lemme know if you need some help when you recover more. at least you are back online again.

what rain? how about 6 days this year over 60 degrees? or 2 that made it to 70? i am still using my wood stove.

 

[jimw1960]

I'm thinking about getting one of the BMC V2S motors that hi-power has on sale for $299 (motor only) until midnight tonight. Do you BMC users reckon that is a good deal, or is a MAC motor from cell_man pretty much the same thing? My other option is to get one of the new Crystallyte HS sensorless motors.

 

[dnmun]

i'm thinking the same thing, gotta decide by tonight.

 

[neptronix]

They are similar enough that i wonder why anyone would buy the BMC.
I have completely disassembled mine and compared it to pictures of a BMC disassembly, no major changes that i see.

BMC do have a leg up, in the fact that they have a stronger clutch and gear set at the moment. But you can put a BMC gearset in a MAC motor.

They both have the same weaknesses for high power use.. small windings.. axle design doesn't allow fat phase wires.. keyway slot insert instead of a spline or double keyway

If you're okay with under 2500 watts, either will work great. I think my MAC motor in a 26" wheel cost .. $185 or so.

 

[jimw1960]

Thanks. I think I'll pass on the BMC fire sale this time.

 

[snowranger]

From what I hear, the BMC has axle seals for the rain, and the MACs do not. Can someone confirm this?

The V2S in the fire sale is of the 2nd generation clutch design which seems to have reliability issues, but the new V2T seems to be a bomber motor. I'm considering the new V2T but that will require some rethinking my battery configuration.