How to mount a wheel to a weed eater engine (direct drive) when building an r/c car?

I want to use a weed eater engine to make a fast r/c car. I have already stripped the engine down to it's basic components (removed all the plastic leaving only the bare engine) to make it easier to mount to a to the vehicle.
I pulled an 8" pneumatic wheel off of a Razor electric scooter which i plan to somehow mount to the clutch system of the engine.The idea is to have a direct drive system to cut down on the complexity of a chain drive (I have the chain drive off of the electric scooter). To do this I'm thinking of bolting the wheel (which has 3 treads that previously mounted the sprocket to the wheel) directly to the bell of the clutch (the part that the clutch engages at a certain rpm and connects to the engine to the driveshaft of the weed eater). Is this a good idea or is the bell not strong enough to bolt a wheel to?

For those of you who don't know what the bell is that I am referring to: http://i1.ytimg.com/vi/6FcFkbxhAXU/hqdefault.jpg

Once I have the wheel mounted (it will have a single rear wheel), I will use the front end of a spare r/c car for the steering and the drive motor to pull the throttle cable on the engine. This will probably be mounted to a plywood base.

Ideally, the best option would be to have servos hooked up to an Arduino controller to control the steering and throttle, but a WiFi Arduino ($80) (could I substitute it for a Raspberry Pi?) + 2 servos ($30) is outside of my price range.

What do you guys think of my design? Any suggestions?

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Hi epic, i dont want to discourage you but you have another problem, you will need to gear the output of the engine down by at lest 4 to 1 Probably better at 6 to 1 as those little engines have very little torque Have a look at these little gear boxes that fit to pocket bikes One is a CTV transmission and the other a single speed at about 5 to1 http://www.scooterpartsrus.com/529_sprocket.htm
http://www.scooterpartsrus.com/49cc_gear_box.htm

They are cheap will bolt straight on to a 35cc Honda, or Chinese copy and some 2 strokes as well, and you will have a sprocket output at the right ratio for your RC car. You could then bolt you wheel on to the gear box or use a chain.
Ive used them before for a couple of projects and they a very strong and good value for money

have a look at this short video
http://youtu.be/xmW4iJo_8Jw
http://www.youtube.com/watch?v=xmW4iJo_8Jw
Seem the video didn't
embed. bug? click on this http://www.youtube.com/watch?v=xmW4iJo_8Jw

Ok it looks like it might work this time :-)
I have done a couple RC speed boats with weed whacker motors with a friend of mine I did the electronics servos ECT he did the machining.

Don’t mess with the clutch if it is out by the tinniest amount it will vibrate the motor into a million pieces. Take it apart put it back together not a problem add or subtract metal or weight from it out of balance and it can be real exciting.

We added bearings to the clutch housing and attached the drive shaft to the prop with a ball and socket universal joint mounting it to the clutch the same way as drive shaft of the weed whacker did.

Joe
epicnoobpwn (author)  Josehf Murchison3 years ago
So can I buy a clutch drum with a keyed shaft? How would I attach a sprocket or wheel to the clutch?
My buddy that did the machining custom made the parts at work.

Where the ball and socket universal joint is in the Pic you mount the sprocket.

It would be nice If they did make a conversion Kit however I don’t know of one.

Joe
Here is a Pic of the rig.
Answer Weed Whacker.png
So your going for a 3 wheel drive vehicle?

What is so complicate about a chain between the engine and the rear wheel shaft? You don't have to use different sized sprockets. Have each sprocket the same size and it's still a direct 1 to 1 ratio on the drive wheels. No to mention more stability in the vehicle and more traction. The power of the engine on a small car may cause to to waste a lot of time with the a single rear wheel spinning out.

Bolting it to the bell housing would be fine but if the wheel/sprocket has a collar then adding a set screw wouldn't be a bad idea either. But i doubt the engine will create enough torque to cause the wheel/sprocket to be ripped from the housing.
epicnoobpwn (author)  mpilchfamily3 years ago
Yes it will be 3 wheels.
The question is how do I attach a sprocket to the weed eater's clutch?
I think your idea of bolting it to the bell will work, if there is room behind the bell for a bolt head. I'm sure you can find a sprocket that can be fitted to the shaft itself.

Is the shaft threaded or keyed? Either way you can get a sprocket machined to fit the shaft. But that will cost some money and have to be sent to someone with the equipment to do it. But like i said before, if you get a sprocket that will fit over the shaft and has a flange that you can use a set screw to hold it to the shaft would be your best bet. Something like this that is just slightly larger diameter than the shaft. Then if your rear axle is a similar diameter a second sprocket can be slid onto the shaft to drive the wheels.

I think a 4 wheeled vehicle is your best bet. If you go 3 wheeled then the engine is offset to one side which may tip the vehicle over on a turn to that side. With 4 wheels the engine can be centered, the chain drive off to one side delivering the power evenly to the 2 rear wheels offering a more stable vehicle.