bgoetz

I have a Koni Yellow/GC setup, I didn't install it, but the original owner did shortly before I bought it. It currently has 380/440 springs, but I want to go a different direction with some 525 that I have and toss them on the front and then max the front camber.

What is the easiest way to do this, if I just unbolt the shock and not the top hat can I just unbolt the bottom of the strut and slide it right out, leaving the top hat in place?

Do I need to re preload everything?

Is there any way to calculate how much higher these springs will cause the car to sit (same spring type, same length)?

iamxpl

take the whole assembly out. its only 2 more bolts. You need to look up motion ratio i believe.

bgoetz

I found those, but how can I take that and calculate the change in height? The ratio I found is .70 front, .67 rear

Slowcrash_101

Motion ratio means that you will lower the car by one inch for every .70 inch you shorten the shock. You will also need to calculate your ride frequency to know what the best springs to use. Combined with a damper force plot and you can make a very educated guess. Any more in depth and you would need a post rig and actual testing. Both of which are prohibtly expensive for most of us s2000 owners.

bgoetz

Yeah 525/440 is where I am headed, figure I have nothing to lose by tossing the 525 on the front, if I crank the front camber out and the car feels like it understeers too much I will just toss 500lb springs on the rear. Might as well at least try the 440s as they are currently on the car.

So with regards to ride height, if the springs are the same length only 145lbs stiffer is there any way to at least estimate how much lower I will need to adjust the perch to keep the same height?

ZDan

With 525/440 springs and .70 front and .67 rear motion ratios, your wheel rates will be 257 lb/in front, 198 lb/in rear. Seems way too front-stiffness biased to me, and a HUGE swing in F/R stiffness.

To maintain same ride height going from 380 to 525 lb/in front springs, assuming 750 lb on each front corner:
Force in the spring is going to be 750 lb / 0.70 = 1071 lb.
Deflection of the 380 lb/in spring is 1071/380 = 2.82"
Deflection of the 525 lb/in spring will be 1071/525 = 2.04"

You'll have to move the perches in the "lowering" direction by (2.82-2.04) = 0.78"

bgoetz

Thanks Dan!!

I am kinda thinking along the same lines with regards to rates, but it seems lots of guys are going with this type of setup. If you look at how OTS Ohlins are setup they come with a similar bias. I have an 01 with a stiffer rear sway, currently it has an oversteer bias, but is controlable but not confidence inspiring if that makes sense. My thought was by going this route I could max the front camber, leave the rear @ -2.2 and hopefully have a fairly predictable track/fun summer/local autox setup. Again if it turns out that this setup sucks, I am out nothing as the 440s are already on the rear.

Thoughts?

iamxpl

thank you for making that easier for us!

ZDan

You would want to revalve your shocks if they are set up for 380 lb/in springs. Personally I wouldn't increase stiffness more than ~20-25% keeping the shocks the same. 525/380 = 1.38, that's a big jump...

bgoetz

ground control said max was 550 before they recommended a revalve. I think when you build the setup you choose the spring rates and up to 550 is just a OTS Koni yellow. Guess we will see how it goes!