how to power single rear wheel ???

[s'ko]

So now that the BRAT is completed.

 

I am jonesing for a new project.

 

I have been kicking around the idea of a three wheeled motorcycle.

 

I would like to make it 3WD. So can anyone thing of a way to make it work that way? I guess I could take a rear diff and put it back there but the weight it a bit of a hinderance. I am trying to get it to weight less than 1500 lbs.

 

are there lighter rear differentials that I can use? Doesn't honda or someone make a shaft driven motorcycle?

 

BW

[Jerry DeMoss]

Yes honda does make a few shaft drive motorcycles,one is the goldwing. Also there were some early 80's three wheeler atv's that were shaft drive made by honda as well as some of the utility type 4wheelers.

[cubastreet]

Moto Guzzis are shaft driven, and I think maybe the BMW boxer bikes are too.

[Reveeen]

making something like this?

 

http://www.freewebs.com/jzrusa/

[s'ko]

something like this

http://www.designmassif.com/trihawk/ WARNING, website has sound. There is the noise of a car starting. turn speakers down or off at work.

 

I bought these plans

http://www.rqriley.com/doran.html

but they are pretty useless. They were not drawn by an engineer and a lot of the measurements you have to infer or use geometry to get. Like the a arms do not have lengths for the various parts. .

It is basically a metal backbone that's made of out 14 ga 8X4 inch tubing. But he doesn't want you to use a single piece of tube, you have to get 14ga sheet metal and bend it to make 2 8X2 channels and then weld it together. Then the engine and stuff goes onto the backbone. It's not a ladder frame. The composite fiberglass foam core body is secured on top of frame w/reinforced mounting points. THERE IS NO CAGE or METAL TUBE INSIDE THE BODY.

If I build to his specs I need to get a yellow jumpsuit that I can wear while driving it. That why I will be the yolk inside of the eggshell.

It's an interesting starting point and the use of EA81 hatchback parts is good. I have most of the stuff in the garage so I am good to go there. Just need the design and the metal to make it.

 

So I was kicking around the idea of the powered single rear wheel. I get a welded rear diff and mount a DOJ cup w/a sprocket welded onto it. This will go a the pivot point of a rear swing arm. Chain will go all the way down the swing arm and then connect to the rear axle.

The swing arm will be located on the passengers side to offset the weight of the driver.

 

main problems are

1) mounting the sprockets (will have someone else weld for me.

2) gearing. Gearing will have to be close to 1:1 so it matches the front wheels.

[Reveeen]

a metal backbone that's made of out 14 ga 8X4 inch tubing.you have to get 14ga sheet metal and bend it to make 2 8X2 channels and then weld it together

 

I would look at using metal industrial door frame. The concept of a single backbone splaying out at both ends (front and back) was developed by Colin Chapman (as far as I know) for use in the Elan, and newer Lotus cars. This was after his space frame efforts (Lotus 7) and his marine plywood fiasco (Europa). I linked you to that JZR page so you could see the way they are built (if you poke around there you get a fairly good look at the frame/body set-up that can be built in any garage using simple tools).

 

Adding in a third wheel driving is going to increase the complexity, not to mention the added weight, I *think* the trick to this type of vehicle is extreme light weight. Plus too, you don't really want to be welding chain sprockets, as they will be a regular maintenance item.

 

BTW: I have a 900 shaft drive Honda in my shed (title), and a 9000 Saab, lined up here for a similar project, just haven't got to it yet.

[s'ko]

nice.

 

Yeah I was thinking of that problems with a fixed sprocket.

 

I think that making a collar on a set of DOJ cups and then bolting the sprockets onto those will be the answer. The other option is the use a shaft driven motorcycle rear end, but I am not sure if you can get matching drive ratios.

 

I have a FT4wd single range tranny from a GL-10 w/3.7 drive ratio.

 

I agree with the weight issue. I will be making it first as a 2WD to get it to pass the weight test and other stuff like that, once it get a bit of miles I might see if powering the rear wheel is beneficial. One think I could do is power the rear wheel via an electric motor so it would be a hybrid. But then you have the weight issues of batteries. There are light weight batteries from Braille but they are pretty pricey.

 

like I said this is a back burner idea that is gonna sit for a long time.

[Reveeen]

Typically, the weight in such a vehicle is about a 90/10 bias with the front being the 90%, I'm not sure there would be a benefit to driving the 3rd (rear) wheel.

Not only would you look at gear ratios, tire diameter on that 3rd wheel would be the deciding factor as to the ratio you want, maybe using a shaft drive motorcycle unit you would determine the final ratio of the unit (final drive+tire, or the effective final ratio) and work forwards from there, adjusting your front tire size?

 

Here (in this neck of the woods) motorcycles do not inspect, nor do they have emissions. You have the option of licensing as "home built" (the insurance company does a double take, and adds a 1000% surcharge), or you incorporate an existing serial number (weld in the steering neck somewhere with numbers displayed where they can be seen) and go with that ownership. I have a V-6 powered trike licensed as a 400 Yamaha, no one the wiser, and affordable insurance.