April 30th was not a happy day for me. In addition to the torque arm failing – mangling the phase wires on my nice new motor and blowing a FET in my controller – I also got snapped by a speed trap. It was apparently one of those automated signs that tells you your speed as you approach and then says “Thank you!” or “Slow down” depending on the verdict. Whle I was taking the bike for a spin on the new motor and testing its responsiveness, I ended up wellying it rather more than I was planning to. The sign duly told me “38mph – Slow down!”, which I promptly did, but I discovered to my dismay that these signs are apparently now fitted with the same automated cameras that inhabit the more menacing gatsos.
[Edit: I’ve just been told by someone on Endless Sphere that the photo was actually taken with a Lidar gun, probably by someone sitting in a parked car nearby]
This was of course my own fault: My speedometer died the first time it went off the clock, and I’ve not got round to fixing it. The speedo/tacho cable and the front wheel assembly that drives it are fine, but clearly something behind the dash isn’t right. Fortunately, I’ve been given the option of 4-hour lecture on road safety in place of a fine and points on my license, and I’ve duly signed up for a class in a couple of weeks time.
Disassembling the hub motor
As I reported last time, the phase wires to the hub motor got a bit chewed up when the torque arm failed and the axle began to creep around in its fitting. Though the repair to the cable isn’t in principle that difficult, I knew next to nothing about hub motors and so was a bit nervous about attempting this job myself. So at first I took it down to a motor specialist at a nearby industrial estate and asked the guy there if he could take it apart and tell me what needs doing. If it wasn’t too expensive, I figured, I’d just have it done proferssionally.
However after a week or so and two follow-up visits, it was clear that he wasn’t especially keen on actually doing anything and had just left it sitting in a corner until I lost patience and made an excuse to take it back. But in the mean time I’d been given some advice on how to get the thing apart myself, and it turned out to be a lot easier than I thought it would be to at least get the stator (the main motor assembly) out of the wheel.
Just a bit of pressure on the tyre and stator pops right out!
Once all the little alan bolts have been removed from the edge of the housing, it is just a case of resting the left-side end of the axle on a piece of wood and applying a bit of force to the tyre by pushing down firmly on it. The stator popped out with very little fuss.
Though I now had access to the inside of the unit, there was still the hub plate (right) that needed removing, and it wasn’t at all obvious what it was that was securing this to the rest of the assembly.
Again, I was unsure about how to proceed, so just thought I would drop it off at a local mechanic’s shop to see if they could tell me how to remove the plate. They said they weren’t sure just from looking at it it, but to leave it with them and they’d “take a look at it”. Unsurprisingly, two phone calls, two visits and nearly two weeks later, it was clear that they were every bit as lazy or disorganised as the previous taker, so I made an excuse and took it back again. I’ve been given some more advice on how to get this plate off, and will give it a go when I find time.
In recent weeks I’ve been indundated with other work, and so for now the bike is in pieces waiting for a rebuild. The LiFePO4 pack has a couple of weak cell-pairs, and is in pieces while I get replacement cells (I have two spare, but still need another couple). The premature decline of these cells is probably due to a couple of times where I ran the bank dangerously low when I really needed to be somewhere even though I was low on juice. I never wired the LVC portion of the BMS into my throttle so it would automatically cut power to the controller if individual cells went to low. Instead I just made regular checks with my bank monitor and kept the bank regularly topped up, seldom letting it run down significantly. The times where I let it run way low would have hurt the weakest cells, and shortened their lifespan, which is one of the risks you take if you operate ‘without a net’ like I do. The cells, though, can still be put to use in non-bank related projects, but are making enough of a dent in the range to warrant replacement.
The lithium pack – two weak cell pairs need replacing
I’m also awaiting the repair to my controller, but can run just fine on one of my cheap spares until that comes back from Lyen’s little workshop.
Maintenance on the battery box, swing-arm and centre-stand
While the battery box is empty, I’ve decided that this would be a good time to sort out a broken weld on one of the brackets securing it to the frame (courtesy of a massive pothole that nearly floored me), and a split along one edge – again from a weakened or poor weld (Chinese quality control at work). I have an arc-welder now, so I’m going to attempt this myself when I can find time.
I’m also going to take care of the centre-stand and swing arm. They’re both a bit tatty looking and rusty round the gills, so I’ll take them off and give them a respray. The stand also needs extending by about an inch to accommodate my bigger tyres, so another weld-job is in order there too.