jeg242s said:
thanks for the reply. Much more than I could have hoped for. One question though what is a "halo bar"? My sister recently ran mine into a sign and the sign fell on top of the car punching a hole in the top and was considering what to do to "fix" it. I didn't know how much support the roof gave. I'm thinking if I cut just the flat part out and had a "primitive" roll cage welded in. (Primitive meaning just a bar going across behind the drivers head and back seats heads, and tacked down to the floor. Also a bit of "triangulation on the bars going behind the driver/back seats) Just wondering if you guys thought that would work or not? It's be used for a bit of DDing and a bit of off roading.
Having a "tight" repair should work. The roof panel is NOT structural, but it IS reinforcement.
I'm planning on taking the sunroof out of my 88 (when I can get an OEM roof panel someday - I'm tired of it raining in my truck, but I'd like to have it look original and not hacked-up) and I'm considering getting a "no-weld" kit from Eastwood to do the job. I'll still have to "flange" the edge of the hole (so the repair panel sits flush,) but fixing the panel in place is done with a structural adhesive and rivets. Should be plenty strong for the loads on the panel - the rivets are strong in shear, and the presence of a mechanical fastener should be enough to keep the adhesive (OK, "glue") from shearing loose.
I'd expect something similiar should work for your repair - moreso, since it's smaller.
Oh - a "halo bar" is the loop at the very top of a full roll cage - forming a "halo" around your head. Thus, the moniker. If you have a full-chassis cage, you'll have a loop around the top, and that is the halo.
If you're going to use a cage for off-road without any backseat pax, I'd at least design in a "half-halo" (from the windscreen eyebrow to the C-pillar, behind the front seats) and have that triangulated in place. If you EVER think you're going to haul pax offroad, have the half-halo go to behind the rear seat (to the D-pillar.) With that triangulated, you should still be OK - but a "full" halo (from the windscreen to the liftgate) would still be best - you could support that at a minimum of six points, and triangulate everywhere.
Anything else I can help with? You might want to pick up a book on race chassis design - I don't recall the title at the moment, but Carroll Smith wrote a damn good one, and it's subtitle was "How to Build Winners That Don't Break." The man was only a lead racing engineer for 30 years or so... I have found all of his books highly useful in my researches, and I've got to get a couple to finish my set.
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