I bought this bike to use as a daily driver, and my main reasons for trips into the city are grocery runs and takeout meals, smaller fabrication materials trips, post office runs for my little mail order hot rod parts business. Options are to put a little rack on the back fender for a soft tail trunk--but it looks so clean right now, big saddlebags (not on this chopper), a custom trailer, or... and this is my preference... an ultra-light DIY 'leaner' cargo sidecar to carry a cooler and several grocery bags.

Turns out the geometry is simple: you just make two pivots inline with the bike's wheels, with the front slightly higher than the rear to aim sidecar subtly in direction of turn due to differing arcs. Aluminum box would net a really light, rigid frame, and an Akront or similar aluminum rim would complete an ultra-light rig. I think a simple swing arm suspension with a light-duty coil over ATV shock would reduce bounce and keep the tire on the pavement without inducing 'bump steer.'

Now, on these old bikes, one can utilize the OEM sidecar mounts (see pic), making fitment a snap. Well, I won't use the rear because it's out of line with the tires; just the front mounts to hold a custom center pivot. But there's a space on the aft end of a plate that used to mount the steel yoke for the rear passenger pegs just behind the tranny--and it's just a touch lower than the front sidecar mounts. So, that oughta be okay if it doesn't interfere with the shotgun pipes...

Best of all, I don't think I need to register a sidecar separate from the bike itself.

I've talked the wife into a spool gun for Christmas, so all I need is a few weeks off... I'll post a sketch of the frame plans as it comes along...


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I am wondering if you are aware that way back when there was a company that made "Flexible" side cars, pre-war.

https://thekneeslider.com/flexible-tilting-sidecars/

Maybe some of the figuring is already done for you, with some research into how they did it back then, good luck.

 

Hey, thanks a lot for this. Indeed, reading about Flxible (with the weird spelling) on a different website is what inspired me. I found another website that has videos of various DIY projects and at least one or two manufacturers of leaning sidecars. I can't afford and don't want a heavier, human-carrying car like the commercial offerings, and none of the DIYers was quite what I have in mind.

Essentially, I want to build an ultra light 'flat bed' with low sides to retain cargo, but perhaps with a small fairing made from aluminum panels, primarily to reduce drag but also to look cool. I will add a few of the unobtrusive round LED brake lights I found--extremely low draw and bright light in a compact housing that fit under my bobbed fender beside the existing fixture (see attached pic, which doesn't do them justice: they are bright). Evidently, you can use resistor leads or something to use them dual-intensity as running and brake lights. I've got one of those Cycle Electric generators, so no problem powering a couple of extra bulbs.

I love the Flathead, by the way. Very cool.

 

A new thought--and kind of a bummer. In beginning to sketch the rear arm in my mind, I'm starting to think that the side-by-side Paughco shotguns I have will interfere with the arc as the bike leans to the right. Might have to go with a traditional single fishtail exhaust--which would, however, allow me to fit the original-style tool box I have...

Hmmm... well, also, the kick starter arc might hit it where I was thinking of attaching the rear arm. Need to ponder the rear linkage some more...

 

Put the side car on the other side, back in the day they did either side.

 

Hey, there you go. I'd just have to be careful about center median strips when turning left, but that's no huge obstacle.

The arm would just have to afford enough lean angle so as to pass through the upper and lower runs of the final drive chain. That should be an easy experiment to do.

Thanks for the suggestion!

 

You know, with these attachment points on both sides at the rear of the frame (1st pic), a single-wheel aluminum trailer with a uni-shock would work, too. Less wind resistance, as it'd be essentially drafting the bike and wouldn't increase the frontal area like a sidecar would--though what I have in mind is very low profile.

The other advantage of a single-wheel trailer is that it's easier to dodge semi retreads and other refuse on the highway...

However, I think an ultra-light cargo sidecar is more unique, and it doesn't need to be separately registered like a trailer. Also, the mounts I have in mind would be very easy to release. Also, it's easy to allow clearance for the side stand or I can make a rod on a pivot that swings up and supports the bike at rest. Finally, the sidecar can haul more bulky stuff than an inline trailer (and I don't want a dual wheel trailer) and I can find parking more easily with a short squarish package. Oh: and I suppose I could add a driving light, too...

I was looking at the left-hand side and, indeed, it looks like a properly configured arm could extend behind the sprocket between the upper and lower runs of the final drive chain. I really like the side-by-side shotguns with vintage Sporty mufflers (see 2nd pic), so am leaning toward the sidecar option (couldn't resist the pun...). My original toolbox mount is perfect to attach a custom mount that will grab both mufflers right where they clamp onto the pipes...

 

Leaner sidecars are dangerous. Compared to a normal sidecar. Big reason many that offered them stopped making them. Even Hannigan stopped making them and will not even support one with parts anymore.

 

Why are they more dangerous than a rigid hack? I've watched videos of people piloting them along alpine roads in Europe at a pretty smart pace. . My friend with an old BMW R60 with rigid hack would never go around curves like this.

Could you explain you concern, please?

 

After reading this I couldn't help thinking of Barney Fife with his 1925 Model JD and Side car, They must of had a Blast filming the Episode