Well after looking at the trailing arm thread, Maybey you whould just have them Waterjet from 1" plate:
http://dtsfab.com/index/index.php?topic=988.0
We need a picture of Enemy's setup hint hint. He is the only one on here running rear A-arms that I know of. His didn't seem to have a ton of gusseting, and wasn't as wide based at the frame, which IMO will add quite a bit of strenght to yours.
Ok I decided to grab some of Enemy's pictures from another thread....... Couple crosstubes to keep anything from buckling. No undergusseting for the shock mount.... You better ask DS what tube he used to get a baseline.
I would like to add this for everyone's info. yes a wider stance at the frame would be stronger ( enemy's is 1 1/2 that of the wheel side ) and I like fabr's idea on his front end a-arm mounts. if you were to use something similar on the rear but upright that would help a lot also. on the rear lower h-arms on enemy's rail we did use 1020 dom 1 1/2" od 1" id 1/4" wall tube and three straight pieces across them for bracing. there has been no problem with the arm bending front to back but the tube has bent slightly under the shock. so that is why I say in the above post that fabr's idea of full length shock mounts is a must or atleast 12" long or so. enemy does like to spend half his time in the air. for most this would never be a problem but for those that like to play hard this shock mount idea is a must!!!
the lower h-arm tube on enemy's rail is I think 23" long itself ( 26" long heim to heim ) and the shock is mounted 12 1/2" out from the frame side , just over half way on 1 1/2" od 1" id 1020 dom tube and it has still managed to bend "slightly" after one season, so we will have to build some full length shock mounts ( thanks for the idea fabr ) for the new h-arms. I don't believe plating half the arms would help in fact IMO it would actually weaken the arm for an up and down load.
I would also like to add that if you build with c- channel for frame side arm mounts that you need to tube gusset the mounts to spread the load out and brace the tube back to the frame and or to the other side to handle the load of landing when the track width gets wider and your wing span ( so to speak ) is grabbing a lot more ground, the forces applied to the rear of the arms is very high!!!! hope this is of use to someone.
on another note I still think that enemy and his builder did one hell of a job
