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Author Topic: Monocoque frames  (Read 462 times)

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Offline javelin grl

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Monocoque frames
« on: January 09, 2017, 12:48:01 AM »
Some of my favourite race bikes used monocoque frames (Ossa 250, 750 Norton, Kawasaki KR 500). Just out of curiosity are any readers working on or racing monocoques or using one on the street? I remember Barry Sheene briefly using an air cooled Seeley monocoque Suzuki 500 twin until the water cooled bike was ready in early 1973ish.
A monocoque would definitely stand out at bike shows however frame building is well out of my league!
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Offline sav0r

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Re: Monocoque frames
« Reply #1 on: January 09, 2017, 08:05:03 AM »
I am in the design stages of a monocoque frame as well as engine (just the crankcase), and transmission. My design is technically a semi-monocoque as it uses tubes, stressed panels, and the crankcase as the load bearing members. The crank case also forms the front bulkhead for the control arms (Hossack front end). Right now I am a little hung up on the power transfer aspect of the project, specifically finding OEM transmission internals that can be adapted to my engine design. The engine is a 300cc triple, should make right around 100hp, but will require pretty high RPM to get there, something like 17k-18k. Unfortunately the monocque is mostly a collection of sketches at this point, but I have been actively getting the crankcase into CAD and have it fairly close as far as the function of the engine is concerned anyways. I believe it to be machinable on my machine  as well (harder than you might think with 3 axis). It's a big project that's going to take quite a while, I already have many months just in the conceptual part of the project and have hardly begun sussing out the true details. The financial burden is probably the biggest issue. It's hard to invest in raw aluminum and tooling when the family needs to food.
« Last Edit: January 09, 2017, 08:11:04 AM by sav0r »
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Offline m in sc

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Re: Monocoque frames
« Reply #2 on: January 09, 2017, 09:01:49 AM »
interesting timing. my friend is going to build a bike here soon using a Rockwell 440 snowmobile engine (that's sitting on the floor of my garage)... we (z1 was there as well) started verbal design and came across the idea of incorporating the 2-into-one exhaust as part of a monocoque upper structure. I mean, why not? there will also be some stainless tubing for the rear of the frame but it should be pretty interesting. keep in mind he used to work in f1 fabrication in the uk for Williams and Benneton, and now is a local welding instructor at the college, so the skill set and experience is there. He's got some super wild out of the box ideas.
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Offline javelin grl

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Re: Monocoque frames
« Reply #3 on: January 09, 2017, 11:00:29 AM »
Thanks both look forward to seeing them.
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Offline sav0r

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Re: Monocoque frames
« Reply #4 on: January 11, 2017, 02:36:29 PM »
Sounds like an interesting project, M. Using a CVT or mating to a traditional gearbox? Those 440's were used in a lot of race cars over the years, sprightly units.
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Offline m in sc

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Re: Monocoque frames
« Reply #5 on: January 11, 2017, 02:53:42 PM »
not sure. he was was actually contemplating mating it to an rd case since he saw how small one was.. and belt driving it to a jackshaft in place of the crankshaft and using the conventional trans/case. not sure. personally id like to see a cvt on it to keep it light and simple, but its not my project. also considered mounting it sideways and using a bmw style transmission with a big dry clutch. hes in it for weird and the sake of a fabrication project.

last one he did was a suicide/jockey shift rigid trellis frame contraption based on, of all things, a Kawasaki csr 305.  why? cause it was like 50 bucks. 
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Offline sav0r

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Re: Monocoque frames
« Reply #6 on: January 11, 2017, 02:58:16 PM »
Sounds sweet. I was considering the RD transmission as well. My engine won't generate much torque and the bike should be light, but I'm not sure it's quite up the task.
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