- Location
- Port Orchard, WA
Letterman said:So I just have to ask why flip the top V's?
This seems to miss the intersection idea, there is none on the top of the a-piller, and it also has no intersection on the front or rear at the center of the rig where the V's come together.
Seems like this design would have better intersections, support maximum impact, and not shear:
(sorry for the bad photochop, not much time to play today)
Not trying to rag on it, looks better then any exo-cage I ever built. Just my thoughts, if it was mine I would chop out the 2 V's and flip them for much better intersection points, and it would also put a LOT more triangulation into the design.
the theory is that the diamond gives the same triangulation as what you have, but supports the center for the over windsheild bar better in the case of a full roll.
The whole point of the triangle is to constrain the plane and keep the outside rub rails from colapsing in. the tubes are also to put a structural bar above the driver and passengers head so in the event of a turtle, there is no rock sticking through the sheetmetal and into the drivers head.
as far as the shear, the 'b' pillar holes in the roof, and the d pillar holes in the roof will be RTV'd and bolted to the roof, picking up the whole roof as a shear plane to hold the rub rails from deforming.
the choice to go to the center of the front windsheild bar was because every time an XJ ends up on its roof, its on that bar, and with keeping a windsheild, and not running bars up to the center of that bar from a lower windsheild bar, this is the best way to add as much support as possible.
the diamond connects to the 'b' hoop where the 'b' pillar support bars go down into the chassis and through the roof, gaining the most strength possible for the 'a' hoop.
thoes front corners and rear corners benifit from this, almost as effectively as if the tube went from the center of the b hoop to each corner.
take 3 popsicle sticks.
drill a hole at each end of each popsicle stick.
put pins in them, making a triangle, constrained at each corner.
now stand up your triangle, and push on the the top corner down and see how that corner is constrained from side loading, just as the a-pillar and d-pillar corners are constrained...
hoto:
