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Post by srx660 on Aug 14, 2018 8:28:17 GMT -5
Found this forum about building the Terracraft TC-2 RT while looking at different chassis configurations for my chassis. Still think i will build a square box style with triangulation everywhere possible. The Terracraft TC-2 build www.motohouston.com/forums/showthread.php?t=341951I think the TC-1 2 place tandem trike they build is kinda ugly. Although a nicer body would be nice i still like the basic shape of the TC-2. srx660 |
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Post by DaveJ98092 on Aug 14, 2018 12:23:50 GMT -5
Nice concept. But they used what looks like 0.125 to 0.25 inch wall tubing everywhere so the weight is much more than it could be. Triangulation tubes could be as thin as 0.062" and still take a very hard hit before bending into worthlessness.
The problem of building a trike frame is that you most likely will NOT have an impact in the lower frame area. You most likely WILL slide under the bumper of the pickup truck that pulled out in front of you and your HEAD hits the rear bumper or the rearend. So a very strongly mounted "A" piller is needed in front of your face.
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Post by Liteway on Aug 14, 2018 13:56:45 GMT -5
Good point about the a pillars. Lots of deer around here along the county roads, and they sprint from cover directly in front of you in an instant, especially at night or times of poor visibility.
I stay off the roads at those times, but they can get you in broad daylight too.
I haven't been able to bring myself to weld on A pillars. In order to be effective I would need to run additional bracing from the a pillars to the roll hoop and that brace is something else to bang your head into and makes egress/ ingress a bit harder.
Those are my poor excuses.
If I were building another trike I would try to incorporate them from the get-go because aside from safety considerations the structural advantage would allow a reduction in tubing below the shoulder line.
Yeah, I don't get the .125 tubing thing, as most tubes are under compression or tension and have no bending loads to speak of unless you fail to triangulate effectively. One size everywhere does not make sense. I used primarily 1.125 dia, 058 wall but also .090 (engine attachment points and swingarm main tubes) .065 (front suspension attachment points, doubled roll hoop, swingarm bracing) ,.048 and even a couple of .032s. all 1.125 diameter. The bigger the diameter, the thinner the wall you can use for the same bending strength.
At 80 lbs, bare frame, I consider mine overbuilt.
Colin Chapman was fond of using mild steel 1" diameter .032 in lots of the chassis, some which weighed under 60 lbs! (Lotus Eleven variants.)
He did stiffen things up by bonding/riveting thin aluminum sheet to the tubes here and there, another good technique for minimizing weight, increasing strength.
Of course he infamously didn't give a hoot about crash protection.
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Post by DaveJ98092 on Aug 14, 2018 17:10:52 GMT -5
Most steel motorcycle frames are around 0.032" wall thickness.
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Post by Liteway on Aug 14, 2018 20:43:07 GMT -5
Most steel motorcycle frames are around 0.032" wall thickness. That sounds a little thin Dave, the handle bars on my bicycle are .065 and when I cut up the my donor sport bikes frame to dispose of it with a sawsall it appeared to be about the same thickness as the .065 stuff I had been cutting to form the trike frame. I must admit I did not measure it directly though. |
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Post by DaveJ98092 on Aug 14, 2018 20:57:57 GMT -5
I just went out and measured a cut section of my wrecked Burgman 650, its 0.0394" or about 1mm thick. This was a triangulation bar so they may use smaller tube in this area.
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Post by Liteway on Aug 14, 2018 21:23:47 GMT -5
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Post by DaveJ98092 on Aug 14, 2018 23:21:08 GMT -5
I have not cut any other tubes. That one tube was damaged by a rock or something after my first collision. The bike slid 400 feet and picked up a lot of crud from the shoulder. SO DID I. There is a tube on the other side that runs down by the cylinder head that got bent. Can not see it in this picture. Lots of tubes in a Burgman 650. There is another "SUB" frame up front not shown for the front fairing to hang on.  |
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