The 24 Hours of Lemons Forums → Lemons Tech → door bar bends
For a NASCAR style door bar is it acceptable to have three or maybe even 4 bends? I did a search and didn't see anything that answered this for me. I want to keep the main hoop and A pillar bars as far out as possible and this will make it harder to get the door bars done.
"nascar" door bars bent like you are talking about are not that strong. Could you notch the b pillar to make them intersect the main hoop better?
They liked our cage last inspection we had (summit point '10.) Though i agree the door bars are less strong when bent like this
Its usually necessary to have 3 bends to fit them. Nascar style door bars help absorb impact where a straight section wont, it will just be strong. A 3rd bend will weaken the bar but it is necessary in most cars. Keep the extra straight leg (that reaches the main hoop) as short as possible. A 4th bend may pass if its absolutely necessary and very short (not sure though.) Basically you want as few bends as possible. The main hoop is just to the right of the edge of this pic.
Tieing tubes in like this
will help give them some strength. Keep the door bars as close as possible to the b pillar and the main hoop. Put the main hoop only as far back as necessary. The bottom tube is a straight shot from the front tube to the main hoop. A lot of the impact forces get transferred to the bottom straight tube along with the main hoop and the front tube in a door bar impact so if you want it strong with 3+ bends in a door bar dont skip out on the bottom tube or the vertical tie tubes.
I have also seen where the cage builder adds a spreader plate with a little foot up to the middle of the bottom tube to help keep it from bending in a crash. I dont know if it would be considered an extra point, not that you need to worry about that for Lemons though.
Nascar style door bars usually have a minimum of 3 bends sometimes 4 it's the only way to get them outside the plane of the cage. More than 4 bends and it's just a bent pipe.
http://4.bp.blogspot.com/_0tq6LmDi_Fs/S … +Bar+3.jpg
http://2.bp.blogspot.com/_0tq6LmDi_Fs/S … +Bar+4.jpg
http://2.bp.blogspot.com/_0tq6LmDi_Fs/S … +bar+5.jpg
I think that the operative theory here is that although the bends in a NASCAR-style door bar weaken the tube marginally, the extra distance that is provided between the driver and the bars (and thus from the colliding vehicle or wall) is more important.
You could always weld some plate to the outside of the door bars to provide extra strength and reduce cockpit penetration in the event of t-boning.
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