# The Drawing Board



## mattW (Sep 14, 2007)

The big question I have been asking myself since getting this car is how am i going to get power from the motor(s) to the wheels. It sounds simple in theory, but is not as simple in practice. Below is a view of the car from underneath. There is a reasonable amount of room around the back wheels to fit motors but not really a simply way to get power to the wheels. _Note: You can also probably see the mechanism that allows the car to be steered from behind (the long diagonal rod). I will be removing that as one of the first jobs as it is just getting in the way

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The two options as i see them are 

1) buy new 10" rear wheels with built in sprockets to attach to two seperate motors via chains, these wheels would probably also need brake pads. The only 10" wheel and sprocket i could find was through a company in melbourne on ebay. I think they were for ATV's but they cost about $100 each plus $30 postage. They look nice and would do the job well, but thats more than i really want to spend on this little car. 

2) The other option is to attach two smaller electric scooter motor/wheel/brake drive assembly under the car where they couldn't be seen (see http://secure.oatleyelectronics.com//product_info.php?products_id=193). Ideally these would simply replace the existing rear wheels but with the big wheel arches the car would look a bit strange without visible wheels at the back so i am resistant to remove them completely. The other option is to keep the real wheels and set the drive wheels in line and at the same height with the rear 'show' wheels', I prefer this option as it would keep the car's looking nice. It will reduce the efficiency and i'm sure won't do the cornering any favours but shouldn't be too much of an issue on the kids car. The built in brakes are are nice bonus as is not having to worry about transmission and alignment and those other less enjoyable design challenges. At $32 each these are a much cheaper option than buying seperate wheels and sprockets and motors and brakes and shouldn't affect the drivability of the car too badly. If it does end up a problem i can either set the drive wheels lower so that the show wheels are up a little bit off the ground or i can remove them altogether and try and try my hand at fiberglassing up the rear wheel wells to look better without wheels (could be a useful skill to learn for aerodynamics adjustments on my full size EV but not something i want to do unless i have to). 

If money was no object i would go with number 1, but for ease and affordbility i think option 2 it the way to go. Oatley electronics has the drive assembly as well as controllers, batteries, chargers and even LED kits to make some headlights so i think i will be getting all my components from the one place. Looks like it will cost about $200 to get a 24V system with everything i need so i'll hopefully put an order in after my next pay check (it sucks being a poor student with no savings =P). They sell motorbike style throttles but not pot boxes so i might need to convert the steering wheel to a set of handlebars, but then i can put push-bike brakes on there too so that might be the best plan. I plan to ring the tech guys to see if i should use one contoller with the motors in parallel or run two contollers off a common throttle. Once i get the components i should be able to put this together pretty fast. For now i just need to finish the design decisions and put in my order...


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