Motorcycle engine, motorcycle suspension.
The original plan for the suspension was simple: Buy a Mazda Miata with a blown engine, take out front and rear subframes, narrow subframes as needed, weld subframes to Honda S600 frame.
This would have worked out reasonably well if not for the fact that the S600 is SO MUCH NARROWER than the Miata.
With the rear subframe narrowed the appropriate amount, the diff wouldn’t even fit. This lead to plan b: use the A-arms, but ditch the subframes.
This approach required a new rear subframe to be designed and built to accept the Mazda suspension arms. Fortunately, the lower control arms were so close together that they could just use a common tube on the bottom. There wasn’t a lot of accurate jigging for this; I 3D scanned the frame (that’s why there’s white powder on the frame in the images), drew the new subframe in CAD, and then cut the tubes as closely to the CAD as I could and hope that was enough to self-jig. It worked pretty well.
There were a few months between beginning this project and finishing it, and it got a little rusty in the interim.
Unfortunately, the A-Arms on the Mazda were too long to use in the front, so I had to use custom arms that attached roughly to the stock pickup points on the vehicle side and to the Mazda upright on the wheel side.
Both front and rear use Yamaha motorcycle shocks. The first thing people do when they get a new fancy literbike is to swap out the exhaust and rear shock. This means there are a ton of pretty decent coil over shocks on eBay right now for a fraction of what they’re worth.
After everything was located and welded onto the frame, I took it all apart and had the frame powder coated. I was going to sand it and paint it myself, but I remembered that I hate both sanding and painting.