# Front wheel direct drive



## Salty9 (Jul 13, 2009)

It's hard to visualize the geometry you require. Do you have dimensions or drawings? Generally speaking, CV and U- joints are happier rotating around the same axis. I discovered this with a lifted Jeep I had that ate U-joints like free bar peanuts.


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## somanywelps (Jan 25, 2012)

2 13 inchers? That's what they use for electric busses...


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## JimDanielson (Oct 19, 2008)

I want lots of torque, so I am making a large diameter motor. The lamination stack will only be about 3-4inches thick. It will only spin up to 1500rpm


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## CrazyAl (May 9, 2011)

Will you be having direct drive via the differential or straight into the drive shafts?

What type of motor are you building?http://www.enstroj.si/Electric-products/emrax-motors.html


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## somanywelps (Jan 25, 2012)

JimDanielson said:


> I want lots of torque, so I am making a large diameter motor. The lamination stack will only be about 3-4inches thick. It will only spin up to 1500rpm


Weight of said motors?

What were your speed calculations?


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## JimDanielson (Oct 19, 2008)

CrazyAl
-AC induction
-Straight into drive shafts
-Do you have a link to the Australian guy's conversion project with direct drive?

somany welps
Motor Weight should be ~70lbs.

I am not sure the OD of this exact tire. But, if it is 20" OD, that gets to theoretical top speed of 89mph.


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## somanywelps (Jan 25, 2012)

JimDanielson said:


> CrazyAl
> -AC induction
> -Straight into drive shafts
> -Do you have a link to the Australian guy's conversion project with direct drive?
> ...


That sounds about right. Cooling?

And your (estimated) peak torque (and the associated current) for one of your motors?


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## JimDanielson (Oct 19, 2008)

Initial motors will only be aircooled, but there will be a substantial amount of surface area on the outside of the motor.

I have not finalized the design on this specific motor. I am prototyping a smaller motor first (half the number of poles and less then half the torque). I will shoot for about 600ftlbs each motor or more. As 650amps is about the max on curtis or Gen4, I will be aiming to not exceed that.


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## iti_uk (Oct 24, 2011)

I would think that the best plan would to be to build your own front subframe for that Tercel which would allow your motor shafts to run close-to-inline with the wheel hub axes.

For your application, you will need custom half shafts anyway, since the originals are likely to be asymmetrical in length and altogether too long to allow two motors to sit back-to-back.

Keep us posted, I'm looking forward to seeing your motors!

Chris


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## Nabla_Operator (Aug 5, 2011)

*Re: Front wheel direct drive (1000 Nm)*

For convincing performance, you need approx. 1000 Nm if you propel the wheels directly, without a gear. That is enormous!

Usual ICE family cars give 100 Nm torque (at the crank shaft) * 3,5 (in first gear) * 3,5 (differential). 

It will be really difficult to find such a motor of which the diameter is small enough not to hit the road.

---nabla---


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## JimDanielson (Oct 19, 2008)

*Re: Front wheel direct drive (1000 Nm)*



Nabla_Operator said:


> For convincing performance, you need approx. 1000 Nm if you propel the wheels directly, without a gear. That is enormous!


I was planning 2 X 600ftlb motors, ~~1600Nm total

But, I decided against this car because I dont think there is enough room around the steering system. Probably will be looking for a RWD car


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## danieltribb (May 19, 2012)

could you share some information of the motor? ?kw, [email protected]?rpm .


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## JimDanielson (Oct 19, 2008)

danieltribb said:


> could you share some information of the motor? ?kw, [email protected]?rpm .


I have more info in this thread: http://www.diyelectriccar.com/forums/showthread.php?t=73807

but the plan is ~30kw, 200ftlb, and 3000rpm max on the first motor. Stator is now built, waiting on rotor parts.

the seconds motor will be much higher torque, but about half the top rpm


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## electro wrks (Mar 5, 2012)

It looks to me your potential donor car is a rear wheel drive. It might be easier to start with a FWD car.


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## toyolla2 (Jun 21, 2010)

Jim,
going from a multi-ratio gearbox to NO gearbox is like throwing the baby out with the bath water. Direct drive is being successfully used with Chinese rail cars for reliable 300Km/hr usage, but they employ really low diameter wheels and, more importantly, a 4 wheel bogie at each end giving each railcar the luxury of eight direct drive motors. The added room under the railcar allows designers to spread the effective motor mass over a greater area. The overall effect is to not only multiply up the torque but significantly increase the total combined cooling surface area of these smaller motors thus permitting more horsepower per motor.

However in your case two motors just doesn't cut it - there is only a 26% cooling advantage by slicing a single large motor in half. Also the 3000rpm you quoted ??

You may be interested to know that the bench mark with the 13" rims on the Prius allows it to max out the axle speed at 100 mph to 1500rpm.

Please consider going the other way with 400Hz motors and a 10:1 planetary built into the end bell of each motor as per GM's Impact in 1990. They happen to have used FWD with their car but RWD is probably the best way to go as it is unlikely to compromise the turning radius.


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## evwannabeee (Nov 23, 2013)

any updates on your motor direct axle construct?


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