Using Honda springs for coil overs

[roman]

NoHachi Wrote:Coilovers don't keep springs captive...at decent ride heights. You need a helper for that.

Keeper springs only add extra downwards suspension travel, below the static ride height. The ride height 'up' from there is determined by the spring rate of the main spring, the weight of the car, the length of your shock absorber, and how high or low your bottom spring perch is with a particular spring.

Quote: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.

Yes, but then how do you calculate the affect that roll has on your car at 1G? you'd need to know swaybar spring rate, static and dynamic roll centre position, centre of gravity, leverage on spring by suspension geometry, and weight of the car at each corner presumably. And then work out how to calculate how much this is going to tip your car at a certain G force.

And then its still a guesstimate at best, until you take your car out to test.

Dont get me wrong I'm all for having as much suspension travel as possible! But when ride height becomes lower and the spring rates get harder, there's less scope for potential suspension travel anyway. It's the limits of hitting wheels against bodywork etc that is more a determining factor in how much suspension travel under compression that you can have.

Quote: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.

I agree that 4.8kg spring will be equivilent of a softer spring in the case of the double wishbone, because the spring is further inboard and the leverage on it requires a harder spring to accomodate. (is that what you mean by motion ratio?)
This isnt bad news though, it just means that in case of using this spring for Mcpherson strut / AE86 etc theres good spring rates to be had even with the full length spring, if 4.8kg or there abouts is a suitable rate for the application. 4.8kg or there abouts just seems low compared to what everyone seems to reccomend as a good setup though.

Quote: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.

Haha yep.

I'm hoping my car (carina) will be under 1000kgs, but I think the motor/box/diff will make it too heavy for that in a slightly bigger shell than AE86.