1.08 torsion bars
Moving the tires outboard by any means makes the springs softer "leverage"
its going to decrease. The rated lbs are for a lever 12" long (for instance) if you measure the same torque on an 14 inch bar, you are going to see less lbs at 14 than you are at 12. Like a beam style torque wrench, you have that pivot under the handle at exactly 12 so you are applying the force at the same constant length. So in a case where you are going to increase the front track by an inch, you can probably go 8% over rating and have the same stance as the original drum track. Thats just physics talking, I bet a suspension guy could shed more light on that.
Moving the tires doesn't change a thing with respect to calculating the wheel rate of the bar. The effective length of the lever is controlled by the LCA, from the pivot to the lower ball joint.
The center of the tires may change the loads imparted to the lower ball joint because of how they load the spindle, but that doesn't change the length of the LCA. And just because you use later brakes, doesn't necessarily mean you changed the track width. Because that depends on tire offset too. So, even running later brakes, with say, 18" rims and a significant offset, you may end up with a similar track width.
I’m trying to figure out the rate of the SwayAway 1.08 torsion bars and not finding what they are. Also the online calculators aren’t much help as I don’t know some of the technical stuff they are asking for. Does anybody know or can help me figure out what they are?
The lower control arm is 12.875" long. The "active length" of the bar is ~33.8", 2" shorter than the overall length. If you look at the Sway Away website, their calculator explains that the active length of the bar starts about 1/2 to 1/3 of the way down the radius. If you look at a stock bar, that's about 1" from the end, on both ends.
If you input that information, you get
267.4 lb/in for the rate. Which should be about right, if you look at the old Mopar listings for a 1.09" bar. You'd expect it to be about the same with that small of a difference. The thing is, the manufacturer of the bars will sometimes have a slightly different constant for the spring steel they're using, so, different manufacturers don't always publish the same rates for the same size bar. If you look at Firm Feels published rates, they do not match the Mopar Performance published rates. The spring constant they're using is slightly different.
As for Sway Away, you can also just ask them. I've talked to them in the past to, funny enough, get the spring rate on their 1.08" bars for a B-body. They helped also me ID the bars as being theirs (which I bought 2nd hand). Once I provided them with the LCA length, they got right back to me.
