Circle Track Sway Bar

[JonMortensen]

Cross posted from Hybrid Z

One of the main things that I wanted out of a circle track style hollow bar with splined ends was lighter weight. Turns out the arms that you can buy off the shelf are 3/4" thick steel and are REALLY heavy, so this ended up being a lb or two heavier than the modded MSA bar that I took off.  If you're looking at this for a light weight bar, look elsewhere.

This is probably revision 457 of my sway bar setup. Some of the highlights of my previous attempts: Started with an MSA front and rear bar set. I had originally bought MSA front and rear bars. Then I had changed the rear end links and they ended up hitting the frame rails. Then I got an ST rear bar and modded it by drilling out the bushing saddles and adding zerks. Made double shear control arm attachments for modified stock arms. I tried to get a guy who custom bends hollow bars to make me one, can't remember the name now (Simonson???), but finally gave up after repeated attempts to contact him, including ones like: "I've got cash in hand. Want to buy a bar. You have made the sale. All you need to do is answer this email." No reply, so I finally decided to do the same thing a friend of mine had done successfully: I cut the ends off of aftermarket MSA front and rear bars and welded on 3/8" x 1" steel bar and drilled the new ends for adjustment. Then I mounted the bars on heims joints to reduce friction (more on this later). Then I mounted the front bar on top of the frame rail for splitter clearance. Then I installed an oil cooler, and the bar interfered, so I moved it back underneath, and that is what led to these latest revisions.

The previous bar in its last iteration had the 3/8 x 1" bar stock welded on at an angle so that the end links leaned in towards the fenderwell significantly. I had found that this would give me the best clearance around the suspension parts. Before I ever ran it, Richard (260DET) pointed out that this would give me a falling rate sway bar, so I revised it by bending the ends vertical. There were several adjustment holes on the bar, but after fixing the end link angle, the end links bottomed out on the bar or the control arm mount that I built, so I could only use one hole per side, so I basically spent a lot of time cutting up a sway bar and welding crap to it and ended up with a non-adjustable sway bar with a bunch of useless shit welded to it. I probably should have left it the way it was, but even in that state the whole thing was pretty janky, and the only saving grace was that my spring rates were so stiff that it probably kept the bar from being used enough to bend the ends or snap the welds off. People have a big problem with welding to a spring, and I get that, but having done it and knowing others who have done it on race cars with stiff rates (meaning not a lot of sway bar twist) it works. It's not ideal, and I'm not saying that it is, but it works. It did hold up for 5 or 6 autoxes with 2 drivers but I wouldn't put this up as my best fabrication project. I wanted the new one to be functional, mount on the bottom of the frame, fit under the splitter, and clear the power steering ram on the rack which sticks out quite a ways on mine. 

Mounting on heims is controversial. One of the main things I was after with my suspension was reducing friction, so when tube80z suggested this as an alternative to poly, I was immediately interested. The idea is to have ears on the sway bar that connect to a rod end that is installed into the frame. This allows the sway bar to move up and down much more freely, but it also allows the sway bar to twist and doesn't restrict its shape while it twists. The bar should make a (slight) S shape in the center, and allowing the movement that the heims joints do should make it just a little bit easier for the bar to do its thing. I don't know that this is a huge deal, I think the bigger thing is allowing the bar to move freely, but there are IMSA and GT cars running this kind of setup, which is what tube80z showed me, and that's what convinced me to try it. I already had reinforced the stock sway bar mounting areas with a plate on top and bottom of the frame rail, and tubes connecting top to bottom in the front and back of the plates. I had used a pretty thin walled tap tube, but later decided it was probably too flimsy, so changed to a much thicker walled tube welded nuts on top and bottom. I'm still using those tubes. This still produces a lot of "WTF are you doing?" kinds of comments. Back in the day Cameron (Heavy85) was pretty outspoken as a critic and Coffey seemed to like the idea IIRC. You decide whether it's great or a waste of time and effort or doesn't make any difference at all. I was convinced enough to do it. 

The stock bar has the dip in the middle for oil pan clearance, and with the ears I had on the stock bar the center part of the bar would hit the splitter as it moved. I was hoping that the straight center bar would improve things, but no, just created a different problem: it hit the power steering ram. I figured I could use longer mounting ears to drop the sway bar down away from the ram. It was tough to see how everything would line up when it was all done, so I made them longer than necessary. I spent a lot of time making sure that the end links wouldn't bind and that the bar could move all the way through the suspension travel without hitting the ram or anything else. Had to trim sections off of the arms as well for sway bar clearance. 

The arms are very thick and strong, and I was only able to put about 1/16" bend in one with my 12T press. Was thinking of cutting or grinding them thinner so that I could bend them, or just giving up, but found a local metal fab shop with a huge press. Took it down there and explained what I wanted and watched/helped as the guy bent them to fit. Also wanted double shear so I welded an extension to the arms as well, and used high misalignment bushings on both ends to keep it from binding. Found that 3/8 male and female rod ends weren't short enough, so had to trim the threaded part of both to get them short enough, but there is no binding. The front adjusting hole on the arms is for the droop limiters, not a sway bar adjustment. 

Cleaned it all up, welded, painted, stuck it in the car and the ends of the arms where the bolt holds the splines tight hits the splitter. Now that I had it all on the car though, I could see that the ears were longer than necessary. Cut an inch off of the ears, redrilled and they're on there now. I haven't put the splitter back on, but I'm sure everything clears.  Couple pics of older iterations in here as well.

Off topic: the brake duct doesn't clear the arm, so one of my projects for the winter is to point the brake duct inlet forwards for clearance.