Increased wheel drag and vibration when freewheeling

PaulM

Pedelecer
Oct 29, 2017
74
15
60
Portsmouth
I got to the office this morning, switched off the power at the display unit and went to push my Wisper 705se to the secure bike shed, and there was noticeably increased drag and the feel of cogs turning as I pushed the bike. And now on its centre stand, rear wheel off the ground, when I use the walk assist the wheel spins but once I close the throttle the wheel quickly halts with a bit of a graunchy sound. Could this be a problem with the nylon planetary gears in the hub.? The bike is less than 2 years old so should I take it back to the dealer to be looked at. The dealer I bought it from is about 70 miles away.
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
5,163
2,498
Telford
The clutch is probably stuck. Turn the bike upside down. Get yourself a decent lump-hammer and whack the wheel (tyre) in the forward direction a few times until it frees up.

If that doesn't work, there's probably rust in the motor due to water ingress. That especially happens if you take the wheel off, say to fix a puncture or change the tyre, then put it back on again with the cable exiting upwards instead of downwards. You have to take the motor apart to check that. replacement clutches don't cost much and are easy to install, so not a big problem as long as you can use tools to open your motor.
 

PaulM

Pedelecer
Oct 29, 2017
74
15
60
Portsmouth
Makes sense. I'll give it a go. If it doesn't work do you think a 36v MXUS XF08 motor would be a swap replacement, keeping the same controller, battery and display unit?
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
5,163
2,498
Telford
Makes sense. I'll give it a go. If it doesn't work do you think a 36v MXUS XF08 motor would be a swap replacement, keeping the same controller, battery and display unit?
You can use any motor you want as long as you get the right speed. For a 26" wheel 250 rpm is ideal. 200 rpm is better if you have a lot of hills.

It's very easy to disassemble your motor and replace the clutch.
Remove the wheel (take photo of washer, spacer and nut arrangements on each side of the axle).
Remove the cassette or freewheel with a cassette or freewheel tool. Cassette requires a chain whip tool too.
Remove 6 screws.
Tap axle to remove the motor from the hub.
Remove a circlip (only on some motors)
Slide off clutch.

Replacement clutch is about £25 from Aliexpress.
 

PaulM

Pedelecer
Oct 29, 2017
74
15
60
Portsmouth
You can use any motor you want as long as you get the right speed. For a 26" wheel 250 rpm is ideal. 200 rpm is better if you have a lot of hills.

It's very easy to disassemble your motor and replace the clutch.
Remove the wheel (take photo of washer, spacer and nut arrangements on each side of the axle).
Remove the cassette or freewheel with a cassette or freewheel tool. Cassette requires a chain whip tool too.
Remove 6 screws.
Tap axle to remove the motor from the hub.
Remove a circlip (only on some motors)
Slide off clutch.

Replacement clutch is about £25 from Aliexpress.
Presumably I will need to know what motor I have to be sure of a compatible clutch. I think Wisper used Aikema motors
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
5,163
2,498
Telford
Presumably I will need to know what motor I have to be sure of a compatible clutch. I think Wisper used Aikema motors
Photos show a Shengyi motor, but they probably changed from time to time. You can tell by the markings.
 

PaulM

Pedelecer
Oct 29, 2017
74
15
60
Portsmouth
I'm going to contact the dealer tomorrow to discuss. It's definitely not right so should be dealt with under the warranty .
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
5,163
2,498
Telford
I'm going to contact the dealer tomorrow to discuss. It's definitely not right so should be dealt with under the warranty .
I'm going to contact the dealer tomorrow to discuss. It's definitely not right so should be dealt with under the warranty .
The quickest solution would be to whack it with a lump-hammer. I've fixed a few with that method.

Did you check that the cable goes downwards, because if you changed that, the dealer could hold you liable?
 

PaulM

Pedelecer
Oct 29, 2017
74
15
60
Portsmouth
Yes, the cable exits downwards and it has an axle end cover. I will try a lump hammer to unstick it but was wondering if it might stick again. If I take it to the dealer they might just do the same anyway, so may as well try it myself.
 

PaulM

Pedelecer
Oct 29, 2017
74
15
60
Portsmouth
Yes, the cable exits downwards and it has an axle end cover. I will try a lump hammer to unstick it but was wondering if it might stick again. If I take it to the dealer they might just do the same anyway, so may as well try it myself
 

PaulM

Pedelecer
Oct 29, 2017
74
15
60
Portsmouth
Whacking the wheel with a rubber mallet has fixed it, for now at least. Thanks for the diagnosis and advice. Because my bike has a centre stand I didn't even need to turn it upside down.
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
5,163
2,498
Telford
Whacking the wheel with a rubber mallet has fixed it, for now at least. Thanks for the diagnosis and advice. Because my bike has a centre stand I didn't even need to turn it upside down.
In my experience, some motors might stick once or twice, but they eventually behave normally. Even riding off a curb without power can fix it. The clutch is just three rollers that get wedged in to lock the inner and outer parts together. Occasionally, they get wedged in so tight that they need some help to unwedge, especially when new and everything hasn't become worn nice and smoothe.
 
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