The arms bolt to the flanges that are welded to the mild steel DOM main bar. The reason there are 3 bolts instead of 4 is simply tire clearance. I am running a 245/40-18 tire on a 18 x 8 rim. The tire just kisses the subframe at full lock under severe cornering...just enough to wear off the paint. Sitting still there is no contact at all.
I was concerned a bit about the strength of the flange connection but after running this setup in Velocity since May for over 6000 miles I am comfortable with the flange design. The splined connection is great, except I have a plasma cutter and I don't have a broach, hence the flanged connection!
The hollow bar has a wall thickness is .134". The bar is not rate adjustable, although that is not a bad idea. It is also not heat treated. While common wisdom says you gotta have a heat treated bar, I've been running a mild steeel DOM bar on my C10 truckfor over 2 years. I take it off every 4-5 months to see if it has taken a set or twisted in some way, but its still good. So is the one on Velocity.
The main bar is contoured like the original and will clear an LS1 in a stock subframe. I am confident that it will clear normal SBC and BBC applications as well, but I have not personally tried them.
Thanks for the great questions!
How much is this setup? thanks
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Mike your friendly USAF B-1 CREW CHIEF
72 Chevy Nova in pieces trying to rebulid this bucket of bolts (really just a labor of love)