For those of you who have not had the joy of doing suspension design, particular on a tube-frame car, this crap is a mental challenge. Either that, or I'm mentally challenged, or both. The challenge is that ideally, everything needs to be co-planar so that the bell crank is loaded in 2-d shear. Once there is misalignment among the components you get ugly bending moments which dramatically reduces the stress limit factor of safety on the bell crank.
The following points need to all be (roughly) in the same plane:
- Rocker pivot
- Rocker - damper connection
- Rocker - pushrod connection
- Rocker - antiroll link connection
- Damper mount / pivot
- Pushrod / lower control arm connection
- Antiroll link / antiroll bar connection
Given that 3 points define a plane, you're trying to design a really over-constrained system. Replacing one of the frame elements with that big billet aluminum piece should help a good deal with making sure everything's aligned. The '68 Lola T150 features something similar on the rear of the car, but not quite for the same purpose. The damper and rocker mounts are in single shear which isn't ideal, but you can live with it. The mounts are fairly stout, but still not heavy.
At the same time you're getting everything in plane, you have to attempt to..
- Have good load paths
- Meet your targeted installation ratio and progression
- Make sure none of your components intersect the frame, control arms, driver, or other such things.
I haven't even taken a look at installation ratios yet. I'll have to see how terribly hosed those are and make adjustments. For now I wanted to have something where I knew I could physically locate the damn thing. All of this helps to locate the front anti-roll bar (FARB) assembly, among other things. In this case there will be another pickup point on the front end of the rocker, which will shoot a link forward to the FARB assembly. My intent is to have both the FARB and RARB adjustable from the cockpit.
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