View Full Version : Calculated rear anti-roll bar rates
I posted this today in the what did to your car today thread showing the calculated rear anti-roll bar rates of the typical bars we have or put on our cars.
http://www.audizine.com/forum/showthread.php/472672-What-did-you-do-to-your-B7-today?p=9362344&viewfull=1#post9362344
boostin20v
01-08-2014, 07:58 PM
Would be nice if you posted the info and formula in this thread for future searching. Also be nice to include the Hotchkiss 24 and 29mm bars at the various stiffens settings.
Would be nice if you posted the info and formula in this thread for future searching. Also be nice to include the Hotchkiss 24 and 29mm bars at the various stiffens settings.
Making me work, eh? Will do, give me a few.
Ok, here's the table expanded to include 24mm and 29mm bars made by Hotchkiss. Mind you, that the well known formula used assumes that the main bar is straight (solid or hollow) and the 'arms' are straight as well (but can be at an angle). So, the calculated reaction forces are relative to the bar's diameter, not it's exact shape. Not a big deal, really - we're not splitting hairs here. If I were in a competition situation, I would measure the rates using a bar dyno (I've done data acquisition software and report packages for two of these, as well as shock dynos and fuel flow benches). Anyway, on with the new data...
29.0 mm 1019 lb/in (Hotchkiss)
24.5 mm 600 lbs/in (034 motorsport)
24.0 mm 478 lbs/in (Hotchkiss)
22.0 mm 337 lbs/in
20.0 mm 230 lbs/in
18.0 mm 152 lbs/in
16.0 mm 95 lbs/in
The formula is based on this geometry:
_________B
___________
A /___________\ C
| /____________ \
| /_____________ \
All dimensions are in inches
force = 500000*(BarOD^4-BarID(if hollow, zero if solid)^4)/((0.4244*A_90'Length^2*Bar_Length)+(0.2264*C_hypot enuse_Length^3))
Please don't make me re-derive the constants [;)]
Sorry about the crappy schematic of the bar, I hope you can figure it out!
Would be nice if you posted the info and formula in this thread for future searching. Also be nice to include the Hotchkiss 24 and 29mm bars at the various stiffens settings.
I don't know what to do about Hotchkiss' various stiffness settings, because I don't know what the dimensions of the links are. The formula I posted doesn't consider the link length nor the distance of the mounts to the wheel center.