Bafang BBS02 Stutter

Fordulike

Esteemed Pedelecer
Feb 26, 2010
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Thanks, I'll check this soon, sounds the most likely, except the bafang is not any clever torque sensor, just a cadence sensor I understand, so if cracked or broken why logically does it only affect high amps, not high cadence.
It's only a possibility that it's anything to do with the sensor, but checking that area will also give you the opportunity to check the tightness of the final drive screws. One of mine was loose.

screws.jpg
This isn't a picture of mine, but I swiped it from the net to show you what I'm on about.
 
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robwalley

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Apr 17, 2012
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Diconnected throttle, still juddering. 99% sure now it's only PAS. After putting throttle back, I throttled full power and got 800W for a second and smooth as silk, but PAS above about 600W and the juddering kick in.
 

robwalley

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Apr 17, 2012
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I have read a few reports of owners having similar problems and upon opening the drive unit, finding the PAS sensor disc broken apart.

My own experience on this, is when checking inside the unit to grease the nylon gear, I found mine to be cracked. Mine doesn't cause any PAS issues though, but it'll be one of the places I'll check if I do.
Seen a few strip down video's, but haven't seen this PAS sensor disc yet on any BBS01/02. Can you give us a clue/Pics where this is located?
 

spanos

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Feb 18, 2011
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Diconnected throttle, still juddering. 99% sure now it's only PAS. After putting throttle back, I throttled full power and got 800W for a second and smooth as silk, but PAS above about 600W and the juddering kick in.
That's interesting so, for clarity , does throttle still work silky smooth whislt PAS is juddeery over 600w?

Or was that a one-off?
 

robwalley

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Apr 17, 2012
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That's interesting so, for clarity , does throttle still work silky smooth whislt PAS is juddeery over 600w?

Or was that a one-off?
Yep, cannot repeat the juddering using the throttle.
 

robwalley

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Apr 17, 2012
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..and did you take a flash download presently to compare to what you put in in the first place?
in case those PAS settings have somehow got corrupted?
Now you're just being silly, of course not, but the settings really are fine, they were good for a year before juddering started. Interesting that it started after a long layoff over the winter, although my garage is dry as a bone, no moisture, probably only drifted under 0 degrees a few times. Beginning to think controller needs replacing, fairly sure it's the old type with the bad components anyway, how can you tell?
 

robwalley

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Apr 17, 2012
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lol... of course any flash can get corrupted, if it was me i`d read it and just check your PAS numbers,,, is it really that difficult?
I had to reset them them earlier today anyway, the Eggrider app is so buggy at this first release it wrote current and speed assist settings in series rather than parallel resulting in every even assist being correct and every odd assist (1,3,5,7,9) being 100%, damn strange test ride I can tell you. Used the good ole fashioned bafangconfigtool to write back 11,100,22,100.......99,100. Test ride fine but still juddering at high current in PAS only.
 

robwalley

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Apr 17, 2012
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This is what my two retaining bolts looked like, half way out. I suspect this is what the juddering was, although it felt tight rocking by hand, the torque from the motor was rocking it backward and forwards a couple of millimeters, still unsure why the throttle wasn't doing it though. Stripping, cleaning, greasing motor and cleaning bike now so be a couple of days before next test.
 

robwalley

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Apr 17, 2012
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Note to self. Get reading glasses.
 

Fordulike

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Feb 26, 2010
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Seen a few strip down video's, but haven't seen this PAS sensor disc yet on any BBS01/02. Can you give us a clue/Pics where this is located?
Apologies for the late reply @robwalley

BBS02pas3.png

Located on spindle side of final drive. There's a protective cover on top, which once removed, reveals the disc.
 
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robwalley

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Apr 17, 2012
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Apologies for the late reply @robwalley

View attachment 24792

Located on spindle side of final drive. There's a protective cover on top, which once removed, reveals the disc.
Ta, Eclipse guys sent the same picture and stated they knew of examples of this fault and symtons. Who stock this?
 

robwalley

Pedelecer
Apr 17, 2012
175
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Gloucester
Apologies for the late reply @robwalley

View attachment 24792

Located on spindle side of final drive. There's a protective cover on top, which once removed, reveals the disc.
Got the dual kit disc and circuit from GreenBikeKit for <$25. Arrived in 12 days. Looks good - now to fit.........