Using Honda springs for coil overs

[NoHachi]

Coilovers don't keep springs captive...at decent ride heights. You need a helper for that.
8kg is fine for an AE86 track car if you have a cage or mayor body stiffening. A street car will be giving up a lot of speed and grip on backroads though..particularly on street tires.

Requirements for spring travel are calculated from two influence factors. First you want to be able to absorb spring compression from maximum cornering force. Anywhere between 0.8 and 1.6G's depending on setup. Then you want some extra margin on top of that because you will always overshoot steady state by a margin and also want to be able to absorb bumps during hard cornering.

4.8kg is normal for a honda civic but pretty high for an AE86. YOU CANNOT COMPARE SPRINGRATES BETWEEN CARS WITHOUT KNOWING MOTION RATIO's AND CORNER WEIGHTS! Hondas have high motion ratio's so 4.8 is equivalent to something MUCH lower on a McPherson car. I'm willing to bet 4.8 is pretty sweet on an AE86 street car, so worth a try. Not good for slammed status though.

Oh and most AE86's weigh around 1000kg without the driver, nearer to 1100kg with driver and full tank of gas. Just look around on the internet for pics of cornerweight scales and don't trust people who pull numbers out of their asses like I am doing at the moment.