Increase spring rate. This company has the best selection thickness wise. Other names are more famous, but you don't have as many options to thickness. They are expensive, but when you don't have an option for stiffer springs it is your only option. I wanted my car the same height, so I measured the space between the springs and try to match that. What you see is $163 worth of rubbers and the yellow is a Shore 40A the softest they have, the black I think is a Shore 50A. They have 80A and 95A too. I plan on getting stiffer ones, but will start on the soft side as not to over power the damps.
That will have to be later, I am fighting an embedded kidney stone and they are forcing me ( covid 19 ) to try to pass it, it was 2 inches to the bladder, and 4mm it is a 60% chance. It is a 7 days now and in the exact same spot. I have ok at times, days are better then nights. I have had 4 major events of an hour each of pure torture. I am calling them today to save a slot for Monday surgery since no electives are being done, there are plenty of same day surgery rooms open. Pain killer addiction is now my worry. I HATE HATE these things, but have to use them. The last time I had one I was 20, now I am 57 and they could not see any in the kidney. So kidney stone maintenance will be a new part of my life, as to not get one of these again.
Kidney stones are REALLY bad, so bad that when my brother had a few some decades ago, I promised myself that I would do everything I could to avoid them, and I have since. Your post reminds me to recommit to the steps of avoidance, because the alternative is awful!!
Before I went in to the hospital I was able to get the fronts in. I was not able to throw it into corners in race mode. I just drove it slowly to the Dr's office since my Kona is stiffer then a normal car, it beat me up even with 30 psi tire (normally run 37+) pressure I deflated it to. The front rubbers increased the stiffness a bit and helped reduce roll just a tad, but noticeable. I still have to install the rears later after I get my kidney stent out and can heal to take a stiff cars jostling. Probably a good 2+ weeks out for full race mode evaluation review.
I did some testing this weekend, and some big pluses and a minus. I put the 40 Shore A in the front and 60 Shore A in the rear. I left out the extra 40 Shore A in the rears. My findings are it increased spring rate an est. 10%- 15% which in some corners help on body roll by a lot. The minus is in some corners and clover leaf on ramps it felt a bit rubber bouncing ballish, and I don't think it is a damping issue in any way. Too soft of rubber has been brought in to the springs. So I ordered 95 Shore A for all four corners and I will cut up the others to add 1/2 or 1/4 of the soft ones to tune them on either side of the 95 A implants. 95 Shore A is likened to a skateboard wheel, where a 40 a is likened to a pencil eraser, the 60A is like a rubber bouncing ball. I should have them within 2 weeks for some more testing.
Oh BOY!!!!!, were those 95 durometer a bear. Since I bought the 5 inch and 3 inch diameters and they have to be spread to fit a 6 plus and 4 inch diameter spring. They were so hard, it was hard to open the diameter up after you put one full cut in the donut ring. I put them in the oven with a 2 3/4 to 3 inch piece of steel splitting the donut open. I slowly increase it to 300 degrees to no avail on stress releaving the donut. I can handle them at 200 deg. with gloves and that temp had the same effect as 300 deg. in making them softer to flex more on the install. You drill zip tie clamping holes in the side center to hold them on the springs, since they want to slide down most of the time from spring movement.
I could get the back ones on and greased and zip tied. The fronts were not having any of that, because of they are so much bigger and I was fighting their mass. I came up with taking a side relief grind with the corner of my 8 inch bench grinder stone, in 5 relief grinds. So a "V" cut a 1/4 into the donut side so when I grabbed both ends at the cut and pulled it open I had less material to fight. That helped but there was no way to get that passed the front strut shaft with the boot there. You don't have the leverage to open it unless you are pulling the 100lbs pull next to your chest. So the next idea was to use a 1/4 drill and drill 3 drill holes in the slit 1/2 way into the 1 inch plus material to reduce even more material. I heated the donut back up to 200 deg. and just barely got it past the strut and boot.
The harder rubber got rid of the rubbery feel and the car handles very flat with only a hair increase in ride stiffness. It is remarkable on how flat it is. This will be good for autoX. I added 1/2 a ring of the 60A in the rear and will add the other 1/2 tomorrow. The rear needs a hair more spring rate. I may order another two rear 80A and split the 80 on both sides of the 95 in the rear. The front has less coils so you take out 1 coil with these donuts it makes more of a spring rate increase then one donut in the rear with twice the coil count.
So I killed the minus and when the new rear 80A get ordered I think it will be perfect. I plan on taking these out in fall because when it is zero degrees and lower, the car is very stiff, no need for the added stiffness since I wont be thrashing as many corners in winter like I do in summer.
Hope you’re doin better with your “Stone”.. Been there too and it’s no fun.. Similar to giving birth..
Drink lots of water... Better to hold the phone, than to pass a stone... Good thing you like working on your cars... it’s a good distraction ... Stay well !