# Hub Motors???



## madderscience (Jun 28, 2008)

To sum up pretty much everything I've heard or seen about hub motors:

Hub motors are viable and readily available for small EV's like bicycles, motorcycles and 3 wheelers. 

However for several reasons the technology doesn't scale well to full sized automobiles. The unsprung weight, issues with suspension and brakes, exposure to elements and the amount of torque needed without the benefit of gearing to allow adequate performance make them unlikely to be feasible AND economical for quite a while.

Cheers


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## Thunderhawk (Jul 27, 2011)

That's kind of what I thought, or more people would be doing it and there'd be more info to be found.

So to be more conventional, in the classified area there is a thread titled "Ultimate Conversion Kit! Cheap". What are the capabilities of the "kit" listed, considering a 2,000lb car?

If I'm going to do this, I need to deal with a 50 mile round trip commute and need to do most of that at 75mph, so as to not be the jerk slowing down the flow of traffic.


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## Bowser330 (Jun 15, 2008)

http://www.ev-propulsion.com/motorcycle-hub-motors.html

Would need some custom work to get it mounted into a lightweight car wheel/rim....

30kw peak hub motor (40hp) for 1,300$ + 1,000$ Kelly controller = 2,300$

Can support 400lbs of weight each...

So 4 motors can support 1600lbs, would cost 9,200$, have 120kw peak power (160hp)

I think i read the motor weighs 60lbs...


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## dataman19 (Oct 7, 2009)

Hub motors (aka: Pancake motors)..
..
Great idea - bad practicality.
..
We were investing in a Hub Motor design. The company was stationed in Florida. They had a really great design and fantastic prototype. Went down and looked at their design, everyone loved it, the Engineering Group, the Design Group, the Prototyping Group, even the Bozos in the Investment capital group.
..
Went to set up a manufacturing/assembly plant. In the process built several pre-production prototypes. Even in the Arizona heat, the performance was phenominal. Then the off road testing... Failures... Failures... and more failures. Why???? Why????
..
Finding: Hub motors may work great under ideal conditions. But in real life they have massive problems. The ceramic Composites are subject to micro fracturing due to suspension stresses imposed at the wheel (they shake to pieces). No amount of shock vibration isolation will relieve this.. Once they start fracturing, dirt, moisture and just about anything else gets into the motor.
...
Came up with a fix - mounted the motor on a trans axle assembly and used CV axles to absorb suspension travel and vibration issues. (Kinda like a Corvair or early VW trans axle).
..
Problem was the investment Group (the Apollo Group out of New York) Decided that they had had it. They took their cues from the investment bankers chant "EV's are a FAD Industry, no one will take EV's seriously". So they pulled the funding.
...
The three prototypes are now in the Arizona Scrap Metals yard (they have been chipped up for scrap), and the project is dead.
..
Another $500K + well spent.
....
But I still believe that Pancake/Hub Motors can be refined - I just hate that we had to go out of business because of investment short sightedness.
..
Dave Mason
Phoenix, AZ


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## Thunderhawk (Jul 27, 2011)

Thanks for that info. Maybe they will become viable sometime in the future.

"The possible is what you can do today, the impossible will just take more time."


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## bruceme (Dec 10, 2008)

dataman19 said:


> Finding: Hub motors may work great under ideal conditions. But in real life they have massive problems. The ceramic Composites are subject to micro fracturing due to suspension stresses imposed at the wheel (they shake to pieces). No amount of shock vibration isolation will relieve this.. Once they start fracturing, dirt, moisture and just about anything else gets into the motor.


Very good post... I was afraid of the same. Did anyone consider induction motors. Mostly copper/steal, no ceramics, vibration safe. Just a thought.

-Bruce


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## DJBecker (Nov 3, 2010)

They still face the same problem -- unsprung weight.

Performance oriented wheels are highly engineered to be as light as possible. Being just a pound heavier than other products would put you out of the performance market. Even casual drivers that can't tell a car is 200lbs heavier can feel the difference of an extra pound on each wheel. 

Putting an extra 50lbs on each wheel is absurd if you want handling, comfort and longevity with on-road driving. This is well known. I would expect that someone designing a hub motor would first instrument a mock-up with the expected weight to document the vibration and shock load, and demonstrate why they can ignore generations of common wisdom.


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