Nohachi's suspension ramblings thread

[NoHachi]

Thanks to everyone so far for this collaborative effort. I have some spare time this afternoon, so I'll try to crunch the numbers for the most basic AE86 setup.

@Bean and drako:
The 305mm LCA length, balljoint to ground, LCA pickup point to ground and shock tower to shock tower measurements are the ones I am most certain of (less then 5mm variation). The variation is mostly in the strut length and in the height of the shock tower (+/- 2 cm or so). Also the angle of the strut might be wrong (iPhone measurement), but the numbers seem logical enough. All in all, I don't think I did too bad for a rough model.

Kind request for CAD wizards:
Now that we have the rough basic geometry fixed. If you have time and interest, we could look at the following things:

The car I measured had no cyl head or front apron. As a result the car was light and sitting higher on its legs. The thing had +1 degrees pos. camber. 1st step is to shorten the strut length untill the strut angle is 9 degrees. That should give the stock 0.3deg neg camber of an AE86 and a good RCH baseline.

Second: Who knows how much a typical 8/6 sprung hachi is lowered? Further shorten the strut by this number and then add 33mm's of Roll centre adjusters below the hub mount location. What is the new RCH?

Last: Once we have the shortening/lengthening of the strut down. It should be easy to measure the strut angle in the drawing for each position. Subtract 9 degrees from this number and multiply with minus one. Now you have the theoretical geometric camber. Could someone try and plot a basic AE86 cambercurve? Starting at a 10cm longer strut and finishing at a 15cm shorter strut? This one measurement has serious implications for our choice of spring, so I'll try to confirm everything with on-car measurements later.

@Drako: What did you study? Do you happen to remember what the slope of the line between the roll centres was?
The numbers aren't too shabby..but I still don't understand the design choices entirely. The ford focus has a terrible rch (around 100mm) and a very high cog (600mm or more). Still, they seem to handle pretty decently.