Lafree motor noise

[Tintaglia]

Hi all,

We have a Lafree that has started to make some motor noise. A new noise has appeared to go with the usual one that the motor makes as you ride. The bike is about four years old but hasn't covered a huge mileage.

The noise is is not that loud, a sort of faint screech. It sounds to me very like the "dry bush" sort of noise other electric motors can make sometimes. (Say, a heater motor on a car).

I'm hoping to find someone who has had this problem or knows if I can remove the outer case of the motor to have a look without bits going everywhere

 

[flecc]

Yes, have a look here and you'll see the internal details. There are two circlips holding the chainwheel and motor drive sprocket to remove for which you'll need circlip pliers, and then nine bolts which allow the crankcase to be separated. Hold back the shafts and gears to the electric motor side as you do that. There's a handy projection on one side that you can tap to get the sides to part. There are no bushes in the main unit, all ballrace bearings except the needle roller bearing on the pedal crankshaft. It may be the neoprene sealing sides on the bearings that are dry and making the noise, and they can be grease smeared without ill effect.

There are four more bolts holding the motor in place, and pulling that out is restricted by the cables and a sensor circuit board, a bit fiddly to get back together. The edge of one motor bearing can be seen and a touch of oil onto that if it's the offender might help. I don't think it's likely to be the problem though.

 

[allotmenteer]

Could the noise be due to a broken hall effect sensor wire?

From the teamhybrid.co.uk website:

WORD OF CAUTION: the Hall Effect Sensor wires are thin, delicate wires that can be broken. The most common reason these wires get broken is because the nuts, which secure the hub motor/wheel on the front forks are not sufficiently tightened. If the nuts are loose, there is a possibility that the motor will spin within the forks, wrapping the cable into a ball, and severing the tiny Hall Effects Sensor wires. In many cases, you cannot visually see that the Hall Effects Sensor wires are broken. When the Hall Effects Wires are severed, the motor will not fire properly, i.e., the motor will vibrate or "chatter", in much the same way that an automobile engine will run badly when one of it's cyclinders is not firing. Many people mistake the "chattering" for a bad wheel-center bearing, when it is really severed Hall Effects Sensor wires.

Apologies if this is not relevant to the lafree motor.

Paul

 

[flecc]

Yes, the Lafree is different Paul. It's three Hall sensors are external to the motor as seen below on their board and both are part of a central chain drive power unit. That Team Hybrid info mainly concerns kit motors like their Crystalite. Most production bikes have adequate anti-rotation measures, such as the independently secured torque plate on the Torq's motor.

 

[Tintaglia]

Thanks for your excellent replies flec & allotmenteer! Exactly what I was after. I'm obviously wrong with the bush noise theory then. I can see now that the load on a bike motor makes a ball race or needle roller bearing a better thing and given the quality of the Lafree all round I can see why they've used those.

Funnily enough, I think there might actually be a problem with the crank sensing because if you lightly press the pedal and then take your foot off it, it leaps back in a way I'm sure it didn't before and I think there is a longer delay in the motor cutting out as you stop pedalling since this slight noise started.

I can't really see how it's connected, but it did get the world's worst soaking when we went to look at the electric bikes at the enjoyable Presteigne show the other day.

Interesting to hear the Lafree uses a hall effect sensor, familiar to me in the motor trade in distributors (a rare thing thing these days). Anyway, I prefer to dicuss anything before I dismantle it so anything anyone can add is welcome.

 

[flecc]

It could be something related to the pedelec sensor drum area then, judging from your descriptions. In the picture below you'll see the edge of the pedal crank pawl area, and behind it a white connector. This isn't unpluggable but connects directly into the pedelec sensor drum. Once you've removed the cranks and separated the crankcase halves, you can unplug the sensor leads at the mainboard and completely withdraw the pedal crankshaft from the left casing. Then you'll see the pressed steel sensor drum.

There are circlips at each end securing all the components in that area, so they can be removed to see if anything is adrift or otherwise faulty. It could even be a problem with the freewheel pawls. Make sure you note the order of everything and where the shims belong as the placements are probably critical.

Let me know if you find a broken part that needs replacement, since Giant don't supply individual parts, and I may be able to help out.

 

[allotmenteer]

Hi all,

We have a Lafree that has started to make some motor noise. A new noise has appeared to go with the usual one that the motor makes as you ride.

The noise is is not that loud, a sort of faint screech. It sounds to me very like the "dry bush" sort of noise other electric motors can make sometimes. (Say, a heater motor on a car).

Before taking things apart, are you sure it is the motor? I've found a webpage about curing bicycle noises , perhaps it may help.

Bicycle Noises, Clicks, Ticks, Repair

You never know!

Yesterday I too had an annoying noise coming from the back wheel which I thought might be the motor but when I got home I checked and I had 3 loose spokes which I tightened. Coming in this morning the noise had reduced greatly. I think I may still have one or two still loose which I'll check at lunchtime.

 

[Tintaglia]

Thank you all for your patient replies, having sat up until 2.30 this morning fascinatedly reading through this fantastic forum I see that all the information was already available Incidentally, Flecc, we hail from your part of the world, having lived for 15 years in Warlingham, my wife's short but hilly daily commute to Caterham being the main reason for our first electric bike purchase (an Ecoped with a 36V Schachner front wheel hub drive and Ni-cad battery). We "semi-retired" to Cornwall four years ago but I still work regularly around Warlingham/Caterham. We'll do a proper introduction in the appropriate place "dreckly"

I'm fairly sure the noise is on the motor because it's silent when you stop pedalling, or pedal with the motor switched off. Could anyone with a Lafree check for me if pedals will ping back hard enough to knock you on the ankle if pressed and then let go? (I know, of course, that if you are in the habit of resting the weight of your foot on the pedals at light etc the motor will attempt to drive but I've never noticed this other effect).

 

[flecc]

I cycle to Warlingham quite frequently, so very local to your old haunts.

I don't get that kickback on my lafree, nor ever have done. It seems that it may be something to do with the motor or gears, though it could equally be an electronic fault. The placement of the Hall sensors is asymetric and I think that delay lines may be incorporated in the mainboard.

An out of synch early current feed could do something odd like that you're experiencing, and another possibility is the Hall sensor board adrift from it's mountings. It sits on two plastic posts against the motor wall with just rubber washers pushed onto the ends of the posts to secure it. Since they tend to get grease on them, they could have come adrift. (My photo shows the board completely away from the motor and against the crankcase side.)

You can see that board and position if you undo the four motor mounting bolts and prise the motor outwards. You'll find it difficult to move it far out without pulling the board off it's mounting though (short wires), so have a look as soon as you have a gap to peer through, maybe with a torch. Getting things back into place is a remote screwdriver job through the gap, very fiddly.
.

 

[Tintaglia]

Thanks for that flecc. Seeing your description of the internals I think the Hall sensor board sounds a really good possibility. I'd completely forgotten that the bike fell over recently and we're not quite sure, but it seems that these problems started around that time. I'm hoping to look at it over the weekend. I have to get hold of a crank puller first. (Unless by some miracle a similar looking rotor puller I have for a 1973 Yamaha motorcycle happens to fit!)

The bike noises link is handy allotmenteer. We'll definately be keeping a copy.

 

[flecc]

Could definitely be something displaced then, either that Hall sensor board or maybe a lost connection within the main unit. You'll need that crank puller, it's a standard thread, and if you split the main unit, circlip pliers for the chainwheel and motor sprocket.
.

 

[Tintaglia]

I have it in (many!) bits now, I have taken some pictures if anyone is interested. The culprit appears to be the hall sensor board as Flecc suspected. The hard plastic pegs that it is mounted on have both snapped off completely leaving it trapped but loose between the case and the motor.

Along the way I discovered that the best way to get the motor off is to take the gear case off the other side first, then it is easy to disconnect the short wires that prevent you from pulling off the motor fully. Unfortunately, this means first removing the motor from the frame but this only involves a few bolts and a couple of wires (apologies if I am repeating what anyone else has already posted).

The other thing to note is that the hall sensor board wiring should be disconnected from the main circuitboard inside the gearcase and pulled through, NOT the plug directly on the back of the hall sensor circuit board itself, which is not detachable.

My problem now is how to re-attach the hall sensor circuit board to the motor (you can see where it has broken away on the first picture). I was thinking of a couple of dobs of glue but I am not sure if the glue would react badly with the circuit board. Does anybody know anymore about this?

Here are some of the pictures:

 

[flecc]

Yes it's best to remove the crankcase half first, but I thought you'd seen the pictures on my site here Tintaglia? Apologies for not drawing your attention to them if that's not the case, since I've already shown the internals.

I've found it's easiest to locate the board with a screwdriver blade during replacement of the motor, and with a touch of grease or vaseline holding the retaining rubber washers on the screwdriver blade, pushing them into place with that before finally closing the motor/crankcase interface.

Those rubber washers that push onto the post ends are easily missed during stripping and that's why I mentioned them earlier. As the posts have snapped off, you can glue the board using most adhesives, but make sure the position is exactly right in relation to the snapped off posts for the motor to time correctly.
.

 

[Tintaglia]

Thanks for that Flecc. Sorry about the repetition. I had looked at your pictures, but because my posts had broken it all looked a bit different somehow. Also, I was keen to show that the Hall sensor comes with it's loom attached in case someone in the future breaks something trying to yank the wires directly off the back of the board.

Your website description is excellent but I've never been very good at following written instructions, I just have to get my hands on things before I really understand them

So I don't make a horrible mistake, can you just confirm that the rubber washers fit (as it appears from your description and seems logical) between the Hall sensor board and the aluminium case and not between the hall sensor and the motor?

Do you think I could use superglue to hold the washers in place in the absence of the posts?

 

[flecc]

That's right, the rubber washers push onto the posts after the board is attached, so they sit between the printed circuit surface of the board and the alloy casing.

If you thoroughly clean the black plastic motor wall surface and the slot area of the board, gluing should be ok. but I'm not so sure with superglue. Some types are thicker and will fill a very small gap, but most need an intimate contact between two surfaces which the components like the three Hall sensors will prevent.

I think the best way is to find something just over the thickness of the Hall sensor chips, cut two suitable pieces and glue them centrally over the broken post points. Then you can glue the board to those. Maybe a scrap of rubber or plastic or even wood will do for that. The important thing is that the lateral positioning of the board is accurate, ending up exactly where it would be if it were on the posts, and just about touching the motor wall.
.

 

[Tintaglia]

I'm experimenting with epoxy putty (didn't seem very good) and araldite at the moment to fix the hall sensor board to the motor. I was even wondering about investing in a hot glue gun because I'd like to make sure whatever I use will last under the conditions. On my motor there appears to be a slight recess to allow for the thickness of the hall sensors so I should be able to get a good adhesion between the lugs and the motor.

I was only thinking of using superglue just to fix the rubber washers back in place. I don't think they are strictly necessary once the board is glued in but I thought they might help to protect it from vibrations etc.

 

[flecc]

Those rubber washers could be useful for that.

The hot glue gun might well work on that motor wall. That type of black plastic encasing the motor is quite difficult to stick anything to, but be careful none of the hot glue hits the sensors.
.

 

[electric.mike]

i don't know the actual situation you are working in but i use a hot glue gun for wood work, if you need to spot glue it in more than one place you may not have enough working time with the glue, would a two part filler adhesive be better like plastic padding or silicone
,
mike

 

[Tintaglia]

I need your help yet again flecc! Just as I thought I was on the home straight, I have discovered that the small bearing on the motor shaft is all but siezed. It will only move about an eighth of a turn before it locks. Can you have a look at yours and see what it feels like? I hope it hasn't been turning in the ally case...

I can hardly believe it wasn't noisier but I'm fairly sure it really is worn out.

 

[flecc]

Can you tell me exactly which bearing you mean so that there's no confusion?

If it's showing in my site, you can tell me which one from that.