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Author Topic: GT380 ground up build  (Read 1838 times)

Offline jpmobius

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Re: GT380 ground up build
« Reply #50 on: Jul 10, 2018, 11:27:12 »
Looks like a considerable volume in the big tubes.  Oil tank? 
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0

Offline themotoworks

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Re: GT380 ground up build
« Reply #51 on: Jul 10, 2018, 12:08:03 »
yeah, oil in the cross tube and gas in the main tube, it adds another .75 gallons, so the fuel cell under the bodywork can be smaller

Offline doc_rot

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Re: GT380 ground up build
« Reply #52 on: Jul 10, 2018, 20:01:14 »
Very nice. Reminiscent of the EGLI frames

Offline themotoworks

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Re: GT380 ground up build
« Reply #53 on: Jul 11, 2018, 14:09:38 »
finished machining the axles for the swingarm, they do double duty and hold the rearsets as well, thus the smaller outrigger bearings, most of the rearset force winds up on those bearings and the rearset hanger is kept from rotating by a screw going into the rear aluminum plates... kinda involved but when it's all laid out well it goes together pretty easy, also finished the rear rocker, still waiting on getting the rocker bearings in but they should be here tomorrow and I can start putting the rear end together, will start machining swingarm parts today too






Offline jpmobius

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Re: GT380 ground up build
« Reply #54 on: Jul 11, 2018, 17:01:53 »
That is going to be a slick set up - hope you will provide a thorough description of how all the bits are fixed in place.  Tapered rollers are pretty unusual for a swing arm pivot, though I have often thought of doing this myself as it would seem the optimal means to eliminate lost motion in this very important pivot.  Love the rollers for the foot controls, I have built rear sets doing this very thing (though not coincident with or part of the swing arm axle) and never fail to be pleased with the still perfect and zero play precision motion after many years of use!  Lovely old school fab work on the rocker as well - after seeing the aluminum frame plates I expected you would carve up another block for this part.  I personally am partial to the "built by hand" look of fabrications like this which seem to becoming scarce with so much CNC work being so prevalent - nice!
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0

Offline themotoworks

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Re: GT380 ground up build
« Reply #55 on: Jul 11, 2018, 19:34:39 »
I think I might actually switch back to ball bearings, having the swingarm mounted the way it is due to the engine mounts being waaay off to one side made things very complicated and the sealing system for the thrust bearings is probably going to fail in service, ball bearings are way simpler and still handle the anticipated loading, but with less margin than the tapered ones, but if the thrust bearings leak grease and pick up road grit asap, then that's no good either... good thing there's mcmaster, swapping to ball bearings is just a day away.  love those guys

Offline themotoworks

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Re: GT380 ground up build
« Reply #56 on: Jul 13, 2018, 12:56:48 »



got some more sketches, the design is getting a lot closer to 100% done, starting to convert the bodywork to actual shapes now, kinda interesting working from an artists renderings and to figure out how to make an actual shape that conforms to what the various views are showing...

Offline jpmobius

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Re: GT380 ground up build
« Reply #57 on: Jul 13, 2018, 15:06:50 »
Going to be a good looking motorcycle.  As I think someone else mentioned, don't underestimate the exhaust - it will take up a very large piece if visual real estate not present in the renderings!
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0

Offline RR100

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Re: GT380 ground up build
« Reply #58 on: Jul 13, 2018, 19:08:01 »
Perhaps I missed the discussion, but have you decided upon material and construction method for the bodywork?
As jp said, pretty bike. The rendered muffler placement really fits aesthetically, but seems impossible packaging for a two stroke no?

Good stuff in any event.