ProjectVF - April, 2008

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Here's how the second paper mockup looked. Since everything was printed at full scale, it's easy to see if the design will work or not. Like before, I added reference marks to check that everything turned the same amount in each direction.

After a few tests and some adjustments, you can see that both ends are at 30 degrees in a "left-hand turn." It's just as accurate in the opposite direction and I know where the real version might need adjustability.

This more-detailed mockup took about an hour to print, glue, cut, and tack together. Like the first one, this was cheap and easy.

 

 

 

 

 

 

 

 

 

 

Here's the last steering mechanism I made for the Test Mule. It was crude and simple, but worked surprisingly well. After playing with it for a while, I decided to try it on ProjectVF

 I bought yet-another used kids bicycle and cut off the headstock to use as a pivot. I measured the headstock, forks, and gooseneck to draw them in CAD, then created a cardboard mockup before doing all the cutting and welding.

 

 

 

 

 

 

 

Here's how I transformed a bicycle headstock into a steering pivot. The levers are made from 3/16 bar stock. The bottom lever is welded to the stub of the original forks and the upper lever is welded to the gooseneck. It's not strong enough for the final version of ProjectVF, but for low-speed downhill testing it'll do just fine.

 

Designed for a lightweight, motorless chassis, this is what the steering mechanism looks like. Click on the picture for a closer look. If this prototype does well in testing, I'll build a heavy duty version.

I double-checked and adjusted the rake and trail to be as close as possible to my drawings. It's one thing to create a point in space - finding that point in the real world is something else. I still have room for further adjustments, so fine tuning is possible.

A quick coat of primer helps the different parts stand out, but it's like putting lipstick on a pig.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This odd-looking mechanism fulfills the basic requirements: it can't block the space above the engine, it can't block the rider's leg, and it has to be a 1:1 ratio. It feels solid and doesn't have much slop or free play. Click on the pic for a closer look.

The ball joints are from a Toyota pickup, and being new they're too stiff to turn easily. I pulled them out of the A-arms and used a drill motor to spin the shanks, intending to wear-in the balls a little but got carried away and overheated the nylon socket and most-likely ruined one. I'll go slower next time.

For more information on how the steering geometry works, click on the Technical Research button on the main page.

 

 

 

 

 

 

 

 

 

I bolted the brake calipers onto the forks, then clamped the lever and master cylinder to the handlebar. The lower brake lines are too long with the forks compressed, but for the moment they'll work. I added a salvage yard brake line from an old Suzuki to temporarily tie it all together.

I spliced the brake lines using a double banjo bolt and a scrap block of aluminum as a plug. It's wasn't the safest setup but for a downhill coast sketchy brakes are better than none at all.

When I get the steering and suspension finalized, I'll buy new custom lines but until then this will have to do.

 

 

 

 

 

 

 

 

 

Here's how I transformed a bicycle headstock into a vertical pivot. The arms are made from 3/16" x 1-1/4" bar stock. The bottom arm is welded to the stub of the forks and the upper arm is welded to the gooseneck. It's not strong enough for the final version of ProjectVF, but for low speed downhill testing it'll do just fine.

 

 

 

 

 

 

 

 

A few weekends of 8-hour days have resulted in a rolling chassis with a functional steering mechanism and front brakes. I welded on some temporary footpegs and was able to coast down the neighborhood hill for the first time on ProjectVF (click on the image above for a larger view) instead of the cobbled-together Test Mule. I only reached a top speed of about 5 mph but the steering works. The few slow turns I made took little effort to initiate. I know the suspension works but didn't hit any bumps other than my driveway. The brakes work, too, but the single run was so slow I never needed them.

And so, several years after buying a very-used Honda VF750 for an ambitious transformation, I was finally able to ride the motorless chassis for about twenty seconds with a top speed of 5 mph. Click on the photo to see a larger version.

Next is some testing, some measurements, some adjustments, and on to bigger hills.

 

 

 

 

 

 

 

 

 

 

 

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