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Old 10-09-2013, 10:52 AM
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Graham08 Graham08 is offline
Master Fabricator
Join Date: May 2006
Location: Iron Station, NC
Posts: 1,800

The way sprint car bars work, there are splined ends with shoulders that ride in bushings. Pretty much all dirt cars run 30" long bars with 1-1/8" splines. 29" long bars are also commonly available, and a couple manufacturers offer 26" bars, but they're sort of rare. By "non-standard diameter" I meant the spline size. Stock car sway bars are made in 1-1/4" and a number of other larger splines, but that would all be custom stuff for my application, and none of it is cheap.

The center of the bar (the "effective length") has the diameter adjusted to change the rate. So in solid bars, you're able to get somewhere around a 0.750" or 0.775" diameter as a minimum, and 1.125" as a maximum, in 0.025" increments. Some manufacturers will custom make bars with the center larger than the ends, but the max diameter is limited by the ID of the tube it's going in.

Bars are normally made out of heat treated 4340, so it's not something you're going to modify yourself.

You can have bars custom made shorter...a number of supermodifieds run 18" bars...but then you're at the mercy of the manufacturer on delivery time. Plus, depending on geometry and how the bars get used, the fatigue life can be short.

My problem was that I was going to be limited to a max wheel rate of around 300 lb/in or so, plus the bars, tubes, arms, etc. add up to more weight than the equivalent coil over. So, I'm going back to coil overs in the rear, with the geometry adjusted to get the mounts as far outboard as possible. At least with coils, if I need a different rate, I can get it overnight from several different manufacturers. I think Hyperco's range is like 85-800 lb/in for the 10" long coils I'm going to be running, so if I can't find a rate that works it's my fault.

Last edited by Graham08; 10-09-2013 at 10:55 AM.
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