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Learning how to build Lotus Seven replicas...together!
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PostPosted: July 13, 2016, 10:33 am 
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Bobber wrote:
Still planning on the Big Block? What plans are you working from?


Not following here...

also i sent the main and middle tube drawings.

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PostPosted: July 13, 2016, 1:00 pm 
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Whoops, forgot which car I was working on. But while I'm at it, can I size your chassis for a blown big block Chev? I just happen to have something for you in back.


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PostPosted: July 13, 2016, 1:06 pm 
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Bobber wrote:
Whoops, forgot which car I was working on. But while I'm at it, can I size your chassis for a blown big block Chev? I just happen to have something for you in back.


still not following...

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PostPosted: July 14, 2016, 11:24 am 
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I haven’t added all the tubes yet, but I wanted to see how much strength this structure gets out of the side rails alone. The side rails don’t do much, less than 1000 ft lb per degree. The problem is that the front and rear "boxes" do not tie the rails together well.

The side rails and roll bar are 2”x0.065” wall tubing. Everything else is 1”x0.065”. Chassis bare weight is at 125 lb.


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PostPosted: July 14, 2016, 11:49 am 
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that looks way off from my cad model which says 205lbs. the main suspension boxes are also 2.0 x.065. There are also a few x braces missing in the rear suspension box.

i sent you an email with the tube sizes.

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PostPosted: July 14, 2016, 1:52 pm 
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I threw in some more steel to stiffen it up but I still can’t even get up to 1000 ft lb per degree. Bare chassis weight is 145 lb. Is there an analysis by someone else that may indicate why I’m not getting much strength out of this chassis?


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PostPosted: July 14, 2016, 2:14 pm 
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that still looks off. the rear suspension box should be 2" tube. Not sure why it is like that. here is the only other simulation that i have.


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PostPosted: July 14, 2016, 3:00 pm 
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Yes, right now I am experimenting with the tubes to see who contributes to the stiffness. I've been analyzing the chassis for pure torsion. Is that what your program is optimizing for? Have you analyzed your side rail framework independent of the end "boxes". I may try that.
Were the end boxes designed for Team 321 suspension?


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PostPosted: July 14, 2016, 3:08 pm 
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Bobber wrote:
Yes, right now I am experimenting with the tubes to see who contributes to the stiffness. I've been analyzing the chassis for pure torsion. Is that what your program is optimizing for? Have you analyzed your side rail framework independent of the end "boxes". I may try that.
Were the end boxes designed for Team 321 suspension?


that was all done for me a long time ago. i think it was optimizing for torsion. My suspension boxes were designed to fit my engine and my own custom suspension. I kind of think this thread was hijacked for its original intent of the lotus chassis. Should we start a new one?

Something has to be way off. It was mentioned before that the At-om chassis has around 4k lbs torsional rigidity so mine should be at least that or better... agree?

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PostPosted: July 14, 2016, 4:00 pm 
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I agree it might be a good idea to isolate this piece of thread. I'm seeing something I don't understand in the At-om structure and I have to chase that down. Where did the 4000 ft lb number come from?


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