MAC 10T Jerky start

I'm running a MAC 10T on 14S7P and a 26" tire. Starting on the flat is fine but the start on a 15% incline is not - its jerky (I don't pedal). I'm only 180lbs. I'm trying to improve the bike and don't remember if I connected the hall sensors or not. Perhaps not and I don't remember if there are any.
1) Does anyone have experience with obtaining a smooth launch uphill ?
2) Would hall sensors help ?
3) Should I change to a 12T and 20S - 72V ?
4) Is 72V difficult or dangerous to work with ?
5) Is there a better motor out there for the purpose ?

Thanks, would appreciate any help
Mike

I ran a MAC 10T a few years ago and I remember it being silky smooth on start up, whether on the flat or on a steep hill.
I think the MACs are fussy on what controller you use, and mine had a controller from EM3EV, which I believe Paul tailored to suit the MAC series of motors.

Yes, for sure using hall sensors will improve the startup under load. Sensorless systems really want the motor to be moving before applying power.

I checked, the sensors are connected and I am using an EM3EV controller. Is it possible that the nylon gears are distorting, absorbing the energy and then snapping back ? There is enough power so that is not the issue, its just "snatching" off the line. On the flat it's pretty smooth, not really silky, but not on the steep its quite rough.

Mike

There may be some settings in the controller that are programmable to soften the start. The gears and clutch will have some free play so if the motor starts too suddenly, they could bounce as you say. The solution is really to make the motor ramp up speed a little slower to minimize the shock loading.

Thanks Fetcher. It seems there is hope with a slower power ramp up, although the controller has now started making noises intermittently while the motor doesn't move. Its quite hot as well, hope its not cooked before I've finished the experiment.
Mike

P.S., Fetcher, what is the mid-motor on your ID/face photo
Mike

That's an old MAC/BMC 600W from a Currie drive. Those originally had an integrated controller which was prone to blowing. With an external controller and forced air cooling, I pushed it to 2,500W.

One thing you can check also, with the controller off, try lifting the wheel and spin it backwards and feel the resistance. This will engage the clutch and spin all the gears inside. You should feel resistance, but it should be smooth. If you have damaged gears, you will likely feel it.

No pedal, 15% grade, sounds like a jerky start all right. ( I don't mean you). I'm just saying, flogging the shit out of it that bad, I'd expect some problems.

One possibility is something going wrong with one phase. A bad connection on the big wire, the hall not working, or working well, stuff like that. Any tiny issue would result in intermittent power to one phase when under the heaviest loads. Might seem fine under light load, but on that start, woah. Start looking hard at all the wires and plugs to start with.

It shouldn't jerk with all 3 hitting, but it should go UHHHHHGGGHHH and grunt like a hog. Pedaling hard on a start that steep would help a ton.

Did you ever figure out what was causing the jerkyness on your motor? I have a new motor that is doing the exact same thing, I have 4-5 MAC/BMC hub motors in various rims and a new one I just got off ebay came laced in a 26" rim with controller and throttle all in a kit and it jerks like a 12 year boy that just discovered the women's underwear section of Victoria Secrete catalog.

I tried everything. The controller it came with had a 3 speed switch and on my other bikes i had never had reason to use such a switch or the controller did not even have the option but on this one I decided to wire up and try. Moving to switch 1 after wiring it up helped a lot but it was still pretty noticeable. The next thing I did was swap the controllers with the other bike I had been riding for years thats torqy but not jerky. there is a difference. And that further helped the problem to be less Jerky. And then the last thing I just did a few weeks ago because I had an event come up and I needed a simple lightweight pedal bike and that was the only one I had running. Was I pulled some of the batteries. So I was running it on 48-50v and now I am running on 36v-40v and I really didn't even notice a loss in top speed or power.

In RETROSPECT, I think the whole problem is that the new motor is a 6T and it is just the way it is. It was labeled as a 8T, But I have a 8T from a trusted source I have put many many mile on and this one is geared way faster so it must be a 6T which I think adds to the jerkyness.

But yes, it drives me f**king bonkers trying to ride that thing. Jumpy is one thing but riding something that feels like it has a rubber-band inside that is bounces the motor back and forth makes for a hard ride,