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I talked some time ago about building a trike. Old VWs for a reasonable price were more difficult to come across than I thought they would be. So I have started looking at using a old GL1000 or even a CB750 as the foundation.
I have seen conversions of this type using HD servi car differentials, converted ford diffs, and home brew contraceptions. Being a computer engineer and not a mechanical engineer I am thinking the home brew thing is out. I would not want to ruin a part that could be used to restore a motorcycle so old HD parts are out (and hard to find anyway I am sure.)
So that leaves conversion of an auto or similar diff. I found that web site that promises that "coming soon" they will tell how to convert a diff to chain drive. Since the site looks like it was created in the 90s with every animated gif they could find I am not going to hold by breath for the instructions. I am sure you would want to cut some out of the width and that would require some custom drive shafts to be made. But how does one convert the diff to chain drive? Or is a auto diff just way to heavy to even consider for conversion? I found a company that sells chain and belt drive diffs but $4K for just the diff is a little pricy. If I am spending that kind of money I can get the VW.
Torqueman
Battle Creek, MI
V-Strom 06
Goldwing 03
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It seems to me one of the trike makers used to use rear axles from Ford Pintos. That was a relatively narrow car, so the axles could be used as they were. Of course, Pintos haven't been around for a while, so the salvage yard might be the place to look. They then used a Gold Wing for power, which has a shaft drive. I think I'd be looking for a shaft drive bike, making sure the shaft turned the proper way. I would guess you would want a bike with the drive shaft on the right side, not the left. Then the rear axle from a suitably small RWD car, and go from there. The axle might have to be slightly offset to one side to get the axle input U-joint to line up with the bike's shaft. Tire outside diameters on both bikes and cars are comparable, so the axle ratio would likely be acceptable. The complete rear axle would also have brakes already on it. Hope that gives you some ideas, and hope someone who knows more about it than I do chimes in.
Predictions are very difficult, especially about the future.
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Torque - what kind of system do the old 3-wheel ATVs use?
Now, let me get this right - is it one down, four up?
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| Rootie (and Torque): About a month ago I was given an old Honda ATC 110, a three-wheeler. It doesn't have a differential at all. It uses a solid drive axle, with a chain drive on one side and a brake on the other side of the central frame. It also isn't really wide enough to be stable as a road vehicle, in my opinion. I think the four-wheelers are the same.
Predictions are very difficult, especially about the future.
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I would think ATVs would be too small and week. Those are made for 20HP ATVs. I would bet even a CB 750 engine would snap it in no time. The Pinto is a good idea. I imagine they will practical give those diffs away. I believe it would be necessary to offset it so if you are doing that you would have to narrow it anyway. Unless of course you used a V6 or similar car engine. Not really what I was looking for as I would like to get good gas mileage out of it.
I looked at the Ural setup. No possible way to make that work. Servi car would be best and I found a place with parts but the diff housing was not available. Everything else was. I have a buddy with a foundry in his garage. I might be able to cast the housing if I had one to make the sand mold from. Probably not. 
I was really thinking using the 750cc engine. They are so inexpensive and lots of parts available. Still the chain might be the sticky point if using a Pinto diff. Was the Yugo rear wheel drive? Any of them get saved from the crusher?
Torqueman
Battle Creek, MI
V-Strom 06
Goldwing 03
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| torqueman: I once used a Toyota rear axle assembly to make a 3 wheeler. However, it was electric. I would be inclined to use a rear axle from a Toyota or Datsun, etc. They usually have good ratios, around 3.7 to 1, and they are metric--like the rest of your bike. If you go with the VW, it is more versatile, can have a 5th gear added, and can adapt to a great number of engines, can be used upside down or right side up, or turned around backwards! However, the type 1 VW would require an independent rear suspension--adding complexity to your project. Don't worry about "offset" of the driveshaft. ALL driveshafts are off set, usually in a verticle plane. The important part is that the angle of the output shaft on the transmission (as seen as a straight line through the crankshaft) MUST be the same as the angle on the final drive pinion as seen as a straight line through the pinion. If you get this wrong, you will get vibration, or worse. Sounds like a fun project. Howabout a Turbo Diesel three wheeler?
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Thanks trauscher1. Good information. I have been having a hard time finding a VW for a song that is why I expanded my thinking. I will keep looking. Garage sale season is coming up so maybe something will surface. I am looking for a real low budget project.
Torqueman
Battle Creek, MI
V-Strom 06
Goldwing 03
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