UMI vs. HRpartsNstuff Sway/Anti-Roll Bar

[malibuguy]

Im running a UMI rear bar I bought used from a GN guy locally. Its the 3034 unit, 1" solid.

Works well, noticeable improvement of roll stiffness over a factory f41 rear bar.

 

[UMI Sales]

What is the wall thickness and material on UMI's 1.375" drag bar. HR parts shows a 1.250" diameter 4130 with a .250 wall thickness. We can use strength of materials to determine which one is actually a stiffer bar. though the UMI is adjustable which adds a nice layer of tenability. All things being equal, the .125" larger diameter adds a fair bit of theoretical stiffness over the 1.25".

For the axle mounted anti-roll bar, 1-3/8" OD, 0.250" wall, 34" active torsion length, 6, 7 and 8" arms depending on hole chosen.



The standard mount bar is 1" solid but poses a unique calculation problem and therefore I've never seen a rating for that style.

ramey

 

[1982 SS]

What material? 4130? Given the same (or similar) alloy, the UMI is definately stiffer than the HR parts bar. The only other one that I can find in a larger diameter is trick chassis's 1.625" .083 walled weld in bar. Without digging into the the machinery handbook I'm inclined to believe the UMI bar is probably the stiffest bar second only to TRZ's more exotic weld in double bar. I know I'll be putting a UMI drag bar in mine after I get a 9" in the back.