Increased drag

[Northern Irelander]

I've been running a brushless motor for over 6 months (powacycle 180w), once the battery has died and normal pedalling takes over, is it normal to experience more drag as the motor ages?

I'm pretty certain there wasn't as much drag when new.................. pretty off putting as well, serious drag factor

 

[NRG]

Has the motor got any noisier since new? Could be the freewheel / planet gears need lubrication...not an easy job AFAIK....

 

[Lloyd]

Check the bearings. ON my model car (brushless motor also) I swore it was getting slower, but assumed it was just me getting more used to it

Anyway a year on I stripped it down and noticed the bearings were really rough and full of grit. There were supposed to be sealed units too. I soaked them in motor cleaner then let them dry out and re-soaked them in a light bearing lube.

Next run I got an extra 30 secs runtime (huge increase compared to a rough 7 min runtime in total) and a massively noticable increase in speed. Must of been a huge amount of drag.

I know it is not a bike but it is the same principle. As NRG says also there is the added factor of the drive gears.

 

[Mussels]

What sort of motor is it? Nylon gears don't really need lubricating, SB motors have a light grease in them and it seemed fine when I changed mine after a few thousand miles. The bearings in SB motors are high quality and shouldn't need any servicing, if you disconnect the chain and spin the wheel by hand then a problem should be fairly obvious.

 

[Straylight]

I'm not familiar with you bike, but assume it has a freewheel. If so then I recently found that winter grime had got stuck in between the freewheel and the motor, causing a rather unpleasant scraping sound. Not being too keen to try and remove it, I dripped oil into the minute crack, wiped it clean, then patiently applied Teflon/lithium grease with a tiny paint brush (as it's somewhat inaccessible), leaving an excess around the joint. Since then I've noticed a decrease in drag even compared to when it was new.

 

[Northern Irelander]

Ok thanks all, havent had the gubbins out of the motor,

Just running a standard 6 speed cassette, I have done a few thousand miles in 6 months, winter grime anorl.

The drag is only when I pedal, freewheeling goes well and is smooth.

In fairness, I service the bike and components on a regular basis (new chain, well upgraded chain from original), no extra noise, except maybe at high speed (21mph).

I suspected the internals needed greased, although havent opened up the motor (yet)...........can easily fabricate a tool to do this,

 

[Mussels]

I suspected the internals needed greased, although havent opened up the motor (yet)...........can easily fabricate a tool to do this,

My SB motor just needed a cross head screwdriver. Six screws and it comes apart, didn't even need to disconnect the electrics.

 

[Northern Irelander]

My SB motor just needed a cross head screwdriver. Six screws and it comes apart, didn't even need to disconnect the electrics.

Thanks

I was thinking that, I also read that some are threaded on and unscrew off

Will investigate when I clean the bike at the weekend

 

[flecc]

The freewheel is threaded on, here's what you need to remove one on my website, but you may not need to do that to get to the sideplate screws.

The motor in your Powacycle Puma is probably like the SB ones, and you'll see a Bafang motor opened up on my webpage here, below the photos halfway down the page, together with some text detail on it.

To strip the motor after the wheel is removed, remove the six crosshead bolts on the side plate, then take off the nut on the opposite side of the spindle, holding the spindle still with a suitable spanner on it's flats. Then with a mallet or hammer give the spindle end opposite the cover end a sharp tap which will break the cover seal, then you'll be able to jiggle the cover off and the whole motor core will come out complete with freewheel if it's still on.

Watch out for any shims on the inner end of the spindle and make sure you replace them when re-assembling since they accurately align the gear meshing.
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[Northern Irelander]

The freewheel is threaded on, here's what you need to remove one on my website, but you may not need to do that to get to the sideplate screws.

The motor in your Powacycle Lynx is probably like the SB ones, and you'll see a Bafang motor opened up on my webpage here, below the photos halfway down the page, together with some text detail on it.

To strip the motor after the wheel is removed, remove the six crosshead bolts on the side plate, then take off the nut on the opposite side of the spindle, holding the spindle still with a suitable spanner on it's flats. Then with a mallet or hammer give the spindle end opposite the cover end a sharp tap which will break the cover seal, then you'll be able to jiggle the cover off and the whole motor core will come out complete with freewheel if it's still on.

Watch out for any shims on the inner end of the spindle and make sure you replace them when re-assembling since they accurately align the gear meshing.
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Ahh easy when you know how....thanks

I have all the standard bicycle tools for removing free wheel etc, no problems there,

It was the 'driving the shaft from the opposite side' that I wasn't aware of

I have presses for car bearings and heavy duty stuff, I didn't want to run in ham fisted and damage something, especially when the bike is only 6 months old.

I'll tread carefully

 

[Mussels]

Ahh easy when you know how....thanks

I have all the standard bicycle tools for removing free wheel etc, no problems there,

It was the 'driving the shaft from the opposite side' that I wasn't aware of

I have presses for car bearings and heavy duty stuff, I didn't want to run in ham fisted and damage something, especially when the bike is only 6 months old.

I'll tread carefully

You don't need to remove the freewheel to open the motor up, just undo the screws (with the wheel out of the dropouts) and tap the motor insides out of the hub.

 

[Northern Irelander]

Ok an update, stripped down the hub as suggested, interior was very clean (exception of grease) it was just as flecc suggested motor

I removed all nylon gears (36 teeth x 3) and centre drive sprocket (21 teeth)

I got as far as removing the red collar that surrounds the bar magnets, there was magnetic resistance but it deffo seemed to stop about halfway. I left it at that and re-assembled .............is there any point in completely removing the collar ?? to free anything up

By just lubricating the ball races with fine oil it free'd everything up. There was an instant improvement in the power and pedalling.

The drag came back after about 30miles

 

[Straylight]

Perhaps the oil wasn't sticky enough to stay on the bearings, I'd try a lithium/teflon grease.

 

[flecc]

There's no point in removing the rotor (red collar), just greasing the gears and bearings is sufficient usually.

Try lifting the front wheel up and turning it by hand, first in the forward direction, then in reverse. It should turn forward easily but have resistance when turned backwards. If it's just as difficult to turn in both ways, the internal freewheel may be jamming on all the time. This is most unlikely on Bafang motors, and they are usually riveted together and not serviceable.

However, I've also found that after stripping and greasing they are initially very free but quickly stiffen up a little with a bit more drag, so there may be nothing wrong.
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[Northern Irelander]

Perhaps the oil wasn't sticky enough to stay on the bearings, I'd try a lithium/teflon grease.

Thanks, I used a Li grease, well packed, was thinkin going molybdenum as for CV joints in cars.

I suspect the oil part-evapourated, it was only a light oil, perhaps a synthetic engine oil would withstand any heat fluctuations??

 

[Northern Irelander]

There's no point in removing the rotor (red collar), just greasing the gears and bearings is sufficient usually.

Try lifting the front wheel up and turning it by hand, first in the forward direction, then in reverse. It should turn forward easily but have resistance when turned backwards. If it's just as difficult to turn in both ways, the internal freewheel may be jamming on all the time. This is most unlikely on Bafang motors, and they are usually riveted together and not serviceable.

However, I've also found that after stripping and greasing they are initially very free but quickly stiffen up a little with a bit more drag, so there may be nothing wrong.
.

I have the motor on the rear wheel, with 6 speed cassette, all appears to be fine forward with distinctive resistance in reverse.

There was a complete transformation when just oiled, will try different oil and grease.

I took a reference of the bearing numbers, they were all different make and size/code.

For future reference/curiosity, are these available in the UK, I know most automotive bearing suppliers can order practically any bearing if the size and code number are known.

 

[flecc]

They should be, as you say, bearing availability is almost universal.

Your motor turn check indicates it's working perfectly mechanically, so it can only likely to be friction and the normal drag of the turning epicyclics.

The only other possibility is when the rear of the spindle is overpacked with shims or not pulled in enough by the external nut so that the stator windings are rubbing on the l/h cover of the motor hubshell.
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[Northern Irelander]

The only other possibility is when the rear of the spindle is overpacked with shims or not pulled in enough by the external nut so that the stator windings are rubbing on the l/h cover of the motor hubshell.
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Good point, but on first inspection all looked squeaky clean inside the hub, I'm not sure if anything is fouling.

What was worrying though, on the centre spindle (21 teeth)the circlip holding it was bodged, the 'eyelets' were physically snapped off, so it would fit around the axle, somebody hashed it in the factory, a standard 10 - 12mm circlip fits perfect.

There is approx 1.5mm of longitudinal free travel along the shaft (would need to take a pic to explain this better)

Will report back if any progress