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Old 01-16-2020, 07:01 PM
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Default Chain Drive w/ Axle Articulation

I'm currently drawing up some rough blueprints for an off road kart/buggy build, and right now my focus is on the rear axle/chain drive. I want to do a solid axle with "semi-independent" rear suspension, much like a trophy kart as seen below.

My question is how does the chain cope with articulation? I've watched YouTube videos of similar set-ups (like Grind Hard Plumbing's Jeep kart) that shows the rear axle articulating with a chain drive, and obviously Trophy Karts use the same system, but it was my understanding that while chains can go up and down on a swing-arm like that of a quad or a Yerf Dog Spiderbox, they couldn't "twist". Anybody running a similar setup on their builds? What should I know before trying to build it?
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Old 01-16-2020, 07:48 PM
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The pivot point of the swing arm and the sprocket off the engine need to be in line with each other, same axis to prevent tension issues. So middle of the sprocket needs to line up with the middle of the bolt for the swing arm pivot.
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Old 01-16-2020, 08:28 PM
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I understand how it's supposed to line up to maintain tension for an "up and down" motion, but what about a "twisting" motion? Solid axle quads, for example, can compress but can't articulate due to how the swing-arm is attached. I'm just wondering how the chain is able to twist when the rear axle articulates like seen in the picture below:

Some guys on a different forum weighed in and said (and I quote) "chain drive and axle articulation are a very bad combination", which doesn't always seem to be the case as this is how trophy karts are set up. But at the end of the day I could always remedy this by either mounting the engine to the swing arm itself (although this would massively increase unsprung weight and probably isn't the best for the engine to be taking such a beating) or just take the easy route and have a non-articulating rear suspension like a quad. Just kicking around ideas.
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Old 01-16-2020, 08:42 PM
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Unfortunately you can't have what is poorly called semi-independent suspension. You can't get that movement. You would have to make the sprocket on the live axle on like a pivot of some type that will allow of a lot of travel like that, as well as the sprocket on the engine. Unfortunately, you are either stuck with full independent suspension, or stuck with a swing arm. You would need a gimbal on the axle sprocket so it could stay straight, but the axle running through it lifts side to side.

If you could find a small differential, then make a small drive shaft, run the engine perpendicular from the normal parallel and run the jackshaft to the driveshaft and that will give you what you want. Here's a BAJA SAE buggy that has that exact setup.

Edit: Yeah I have no idea how they get the sprocket to do that without like some sort of gimbal in it to allow the axle to move like that.
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Old 01-16-2020, 08:49 PM
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Oh well, it was nice to think. I know IRS is an option but it's both more complex and expensive. I'll stick with the chain drive and swing arm. I know this is how a lot of crosskarts are, quads as mentioned before, and Sidewinder buggies. If it works for them it's good enough for me!
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Old 01-16-2020, 08:55 PM
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I'll keep searching. Maybe I'll come across a forum that is dedicated to Trophy karts.

So according to Jody (ProtoDie) the chain can handle some articulation, but it will shorten the chain and sprocket life by a lot for it. Here's a link. http://www.minibuggy.net/forum/drive...ns-newbie.html
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