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Thread: Ural sidecar conversion (thinking about it)

              
   
   
  1. #1
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    Ural sidecar conversion (thinking about it)

    Hey everyone

    New to the forum.

    In addition to some fine two-wheeled motorcycles I've owned, ridden, and enjoyed, I also have two Ural sidecar rigs. The older one is a 2007 Tourist, with frankly, enough engine challenges that I'm getting sorely tempted to convert it.

    So... starting to think about a conversion of this lovable tub.


    Kicking around some ideas at this point.

    I've seen a few sidecar conversions (for instance, there's a Dnepr sidehack on evalbum: http://www.evalbum.com/3944). And Ural themselves deubuted an electric a few years back (prototype) using a Zero motor and battery pack (https://www.imz-ural.com/electric)

    So this would hardly be the first. But I believe I still want to give it a go.

    --

    So, some basic design ideas that I'm toying with, and would appreciate advice on.

    1) Hub motor or DC (or PMAC) motor. Hub motor would be relatively simple. Avoids having to deal with the driveshaft. DC motor is simpler. PMAC motors offer more power.
    Not looking for insane power or top speed (it's a Ural!) but would need more torque than an average conversion. Also, I'd like to work towards pretty significant range if I could.

    2) Where to put the batteries? It seems like I'll have a lot of room between where the ICE engine is today, and also the possibility of putting them either on or under the floor of the sidecar.
    Also seems to mean either I don't need the most energy-dense batteries available, or could really add to the range.

    3) I'm not a machinist, have never welded. Mechanical aspects are not going to be my strong suit on this potential build. Advice? Do I find a friendly machine shop? Is it easier than I think?

    4) Those drum brakes... may have to convert to modern Ural wheels with disc brakes, but then there goes the budget.

    Thoughts? Reactions? Advice?

    Thanks in advance.
    (and if this belongs in a different forum section, please let me know).
    Last edited by UralRider87; 18 July 2021 at 1831.
    Ural Rider, thinking about my first conversion

  2. #2
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    Ah,

    Just ran across this over at DIY.

    https://www.diyelectriccar.com/threa...3/#post-863369

    Someone converted a Dnepr (same as a Ural) first with an ME-1003 direct-connected to the driveshaft. Was having trouble, then he switched to an AC-30.

    As someone over there said, "Yes this is a common problem with this set-up. Not enough gear reduction and no way to increase it. The motor turns too slow, draws too much current and overheats."

    This would seem to argue for a hub motor. Enertrac look more appealing than QS. I see they have 10kW air-cooled and 20kW liquid cooled. (though the thought of running two coolant hoses down the swingarm kind of makes my head hurt).

    A hub motor would avoid the whole shaft drive issue.

    yes, adding unsprung weight - but it's a Ural. It's not exactly sport suspension to begin with.
    Ural Rider, thinking about my first conversion

  3. #3
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    A hub motor, used to turn the drive shaft, would work. Enertrac actually did some vehicles using their hubbies to drive drive shafts, or axles. Using a hubbie as a mid-drive with small reduction is a common way to improve performance, and avoid unsprung weight, in E-assist.

    https://www.electricbike.com/12-ebik...-as-a-non-hub/

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    Quote Originally Posted by Warren View Post
    A hub motor, used to turn the drive shaft, would work. Enertrac actually did some vehicles using their hubbies to drive drive shafts, or axles. Using a hubbie as a mid-drive with small reduction is a common way to improve performance, and avoid unsprung weight, in E-assist.

    https://www.electricbike.com/12-ebik...-as-a-non-hub/
    Oh that is really interesting! Not at all what I was expecting but that's really cool.

    I was thinking of replacing the rear wheel of the Ural entirely. Enertrac will lace a custom wheel for you (it seems) so I was thinking of a full drop-in replacement rear wheel. Thus saving having to deal with the shaft at all.
    My concern about the shaft is:
    1) alignment - getting a mid-mount motor and drive shaft properly aligned looks to be a real challenge.
    2) weight & power loss - driving the mass of the drive shaft and the rear bevel gear has to be less efficient than driving the wheel either with a chain or directly (hub).

    But on the flip side, will a hub motor have enough power to drive the (relatively heavy) Ural? It's about 750 lbs right now before engine & trans removal.

    Really neat idea to use a hub motor in a mid-mount with reduction - hadn't seen that before, thank you.
    Ural Rider, thinking about my first conversion

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    Quote Originally Posted by UralRider87 View Post
    Oh that is really interesting! Not at all what I was expecting but that's really cool.
    driving the mass of the drive shaft and the rear bevel gear has to be less efficient than driving the wheel either with a chain or directly (hub).
    Yeah. And yet Harley chose to run a a bevel gear set to a belt drive...go figure.

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    Quote Originally Posted by Warren View Post
    Yeah. And yet Harley chose to run a a bevel gear set to a belt drive...go figure.
    Good point. And in the last comparison I saw, the LiveWire had a greater range than the Zero it was up against. Hm. Perhaps losses aren't all that bad.
    Efficiency vs RPM might be more what I should be looking at...
    thanks
    Ural Rider, thinking about my first conversion

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    Quote Originally Posted by Warren View Post

    Very cool. Do you know how the Miata came out? Were they happy with it?
    Ural Rider, thinking about my first conversion

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    So... Gearing ratios.

    The final drive ratio is 4.62:1

    The wheels are 19" in diameter, and have tubed tires with high sidewalls. They're off-road tires, so do not follow the usual "180/70R-16" specification format. Tire size is 19 x 4.0.

    But easier than all that is just measuring the rear wheel. It is 26.5" in diameter. That means a circumference of 83.25 inches. Or 6.938 feet.

    ...

    Motor rpm range is 900 rpm to 5600 rpm.

    4 forward gears (and 1 reverse!)

    From the owner's manual, the gear ratios are:

    1st 3.6
    2nd 2.28
    3rd 1.56
    4th 1.19

    Reverse 4.36

    Final Drive 4.62

    ...

    Wheel RPM = Engine RPM / (Transmission Gear Ratio x Final Drive Ratio)

    Wheel Speed (in feet/min) = Wheel RPM * Wheel Circumference (in feet)
    Wheel Speed (in feet/hr) = Wheel Speed (in feet/min) * 60 (mins/hr)
    Wheel Speed (in miles/hr) = Wheel Speed (in feet/hr) / 5280 (feet/mile)

    ...


    Do all that, and you get a table like this:

    Gear Ratios.jpg


    The top speed in each gear (27 mph, 42 mph, 61 mph, 80 mph) agrees with another source, so I believe I'm on the right track.


    It should be noted that no-one achieves 80 mph on a Ural. The engine runs out of grunt long before you get there.

    Highest I've ever seen on my more modern 2017 is 70 mph, and that involved a bit of downhill and a favorable wind.

    Highest I've ever achieved on the one we're talking about here (2007) is about 60 mph. Maybe 62. And that was dicey.

    After conversion, I'd be perfectly happy with a top speed of 50 mph on this thing. 55 mph would be great. 60 mph would be amazing.

    ...

    So what does all this tell us?

    A few things.

    1) Overall gearing ratio.

    If we go with an electric motor that spins up to 8000 rpm, we're going to need a total gearing reduction of:

    60 mph 10.5
    55 mph 11.5
    50 mph 12.6

    i.e. something in the 10.5 to 12.5 range, or about 11.5 in the middle.

    If we keep the final drive, that means we'll need an additional 11.5/4.62 = about 2.5 : 1 gearing reduction.



    2) Or if we connect an electric motor directly to the final drive shaft, we have only the final drive ratio of 4.62:1.

    That means, we won't want to spin the electric motor any higher than about 3500 RPM. More likely 3200 or 3300 max.

    FD only:

    RPM Wheel Speed (mi/hr)
    ---- ----
    1000 17.1
    2000 34.1
    3000 51.2
    3500 59.7
    4000 68.3 - that would be really fast on a Ural
    5000 85.3 - definitely in the danger zone here
    6000 102.4 - nope
    8000 136.5 - never



    3) So if I go with a high-rpm electric motor, I would need to limit the top RPM. Or build an approximately 2.5:1 gear reduction.

    Or, if I go with a lower-rpm electric motor, it would probably work just fine coupled directly to the final drive shaft.
    Last edited by UralRider87; 02 August 2021 at 2046.
    Ural Rider, thinking about my first conversion

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