Roll Cage, Back Bracing |
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Roll Cage, Back Bracing |
Randal |
Feb 2 2009, 08:18 PM
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#1
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Advanced Member Group: Members Posts: 4,446 Joined: 29-May 03 From: Los Altos, CA Member No.: 750 |
What is the minimum amount of bar that would need to be added from the back towers to the transmission cross member? Understanding that I am running a bar from the back hoop of the cage to the shock tower.
Could I just run a bar from a plate on the rear side of the shock, midway to the top of the transmission cross member? Just a simple triangle. Would that help? Picture below. |
McMark |
Feb 12 2009, 04:54 PM
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#2
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
Chris, I realize my 'test' isn't very accurate. I only reference it to indicate that the cross bar is quite stable in it original form.
I think the cross bar is absolutely stable in a left-right motion. The bar is only 12" from the shock towers and that's a very short run with a boxed frame to support it. I think in the left-right direction there is very little force. Forward-back is definitely not an issue. Twisting along the length of the bar is tied directly to the shock towers. If the shock towers were magically solid and untwistable/unmovable, then the trans bar would never twist. Therefore, the trans bar twist is directly linked to shock tower movement. The final force I can imagine would be for the center of the bar to move up and down due to the transmission/engine weight bouncing up and down. Since we already know the bar can handle 200lbs + gravity/acceleration of a jump, then it seems to me that the bar would not need much more support. While the stresses of racing will create forces in excess of this 200+ lbs, those forces will not be purely vertical (and if they are, then you are not in a corner, so who cares). So 200lbs at a 90 degree angle (i.e. vertical) does have some similarity to 500lbs being pulled at a 45 degree angle up and left/right. I still maintain that shock tower movement in turn moves the trans bar, and that a solid, unmovable shock towers would mean that the trans bar is solid as well (in every respect that's important). Attached image(s) |
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