Quote:
Originally Posted by strat61caster
Like racecomp says, front and rear suspensions are entirely different, putting the same spring rates will create two vastly different feelings at each end of the car, if I may quote them, the rough math below illustrates it pretty well:
|
Hi strat61caster, I already read that thread and for my part am fully aware. The same math obviously applies to the stock suspension.
The OEM e.g FR-S is 2.3k front and 3.8k rear. So if you put a 10k in the front and divide it with 2.3, you get an increase of 434%. If you equally increase the rear with 434% it would give you a spring rate of 16.5 k.
10k/16.5k would probably be a very bad combo - so that's what meant with that they react differently to increasing rates. In the rear an increase in rate apparently has a bigger impact than on the front - due to the different constructions. Thereby is
not automatically being said, that the same applies to a reduction from the OEM values. E.g. the GT86 (my car) is OEM only 3.3k in the rear, which percentually is a big difference to the FR-S. So maybe the rear suspension doesn't react that much to changes in the lower end of the scale but exponentially more to higher rates? Where as the front perhaps react to changes in a more linear fashion?
So the objective may not be to make a selection in spring rates that
equals in same motion-compensated-rates front and rear. The goal for my part is to make the car handle as neutral as possible, within the limits of the parameters I can affect with my choice of suspension (coil overs / anti sway bars). From the the availability of kits out there and what experiences people report, it seems that as you increase the rates, the motion
uncorrected rates should be about the same, preferably with a slight rear bias.
With the basis, in my case, being dampers matched for 6/5 rates. What can I change, in order of ease/costs:
1) Alignment
2) Anti sway bars settings
3) Spring rates - but limited within the ranging of the dampers.
4) Revalving
With my cheap choice of ST XTA coilovers the last option drops out. It wouldn't have been a cost efficient purchase, and from the start my plan was to see what could be obtained within the limits of 1 and 2. I am keeping option 3 open, but would only do mild changes (like changing the rear from 5 to 6, as I doubt the quality of the dampers would support making big changes. Personally, I think the same logic goes for the Öhlins MP20, it would have been more cost-effective to make a different decision from the beginning, rather than revalve and change springs - hence they got eliminated from my list of choices.
I would like to point out that I am a
theorist. I spent a long time gathering as much information as I could on the subject and still have a lot to learn, which is a process I enjoy a lot.
I still probably overlook a lot of theory and most importantly; the practical experience is still completely missing. So the above may have a lot of errors, which I then hope some else will then correct me on here.