ProjectVF - March 19th, 2008

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Back to the Construction Sequence page

 

 

 

 

 

 

Here's a new and improved CAD drawing of the next steering mechanism.

The handlebars, attached to the steering triple-clamps with an adapter plate, push or pull on a tie-rod connected to the upper pivot arm. The pivot itself is bolted to the right side of the frame. The lower pivot arm, in turn, pushes or pulls on a tie-rod connected to the top of the right fork, which turns the front wheel assembly

 I want the steering at a 1:1 ratio, just like every other motorcycle. Cars have steering boxes, or rack and pinion systems, and thus the steering ratios vary greatly. Motorcycles, with the handlebars connected directly to the forks or upper triple-clamp, are always 1:1.

Here's how the long-suffering Test Mule looks with an all-steel prototype of the new steering mechanism. It took about three hours to get it figured out and fabricated, and the yellow paint helps it stand out. Total cost was zero since everything was recycled from the previous version or came from my scrap pile.

A couple of test runs down a local hill proved it worked better than any of my other designs, with less backlash and more feedback. It looks better, too.

 

 

 

 

 

 

 

 

Here's an overhead view, and if you compare it to the CAD drawing at the top of this page, you can see how closely it follows that design. Getting the pivot arms and tie-rods at 90-degree angles was a key element to success. Keeping the fabrication tolerances tight was another.

Before I start building the real thing, I'm going to do some further testing. I'm want to revisit a few rake & trail combinations and see if this mechanism makes a difference in the amount of effort required to steer at low speeds. Like before, I'll measure the actual forces involved just to make sure I'm on the right track.