Welp, Eibach springs have been purchased. Now I'm sure most of you by now are wondering if I'm just a glutton for punishment, and I think the obvious answer is a resounding YES!
Anyways, they came in yesterday and I had to do side by side comparisons since I now have stock (non-mtech), H&R, and Eibach springs. And away... we... go.
Front springs, from left to right, in order of shortest to tallest, we have H&R, Eibach, and stock.
As you can see from a height perspective, the Eibachs are right in the middle, but there are some other notable differences. The H&Rs have 6 total coils, while the Eibach/stock only have 5, and the H&Rs are much more tightly wound. Certainly a much higher spring rate for the H&Rs. This is important when you start looking at things like "flat ride". This is an idea I learned about from Fat Cat Motorosports, which I mentioned in my last post. In terms of front to rear suspension frequency, you want the rear frequency to be ~20% higher than the front, to allow the rear to settle faster and stay in concert with the front. With this much higher rate in front, I wouldn't be surprised if the frequency becomes higher in the front that rear, causing the rear to still be reacting to the previous bump, as a new bump hits the front. The end result is a non-cohesive suspension that feels much bumpier and less stable over imperfections.
Measuring spring thickness, the H&Rs come in at 13mm
Eibach right around 12.5mm
And stock at 12.5mm as well
Once again, the H&Rs seem to be much stiffer up front than the stock and even Eibach. Given this increased stiffness, it seems aftermarket struts are basically a requirement to keep up with the front spring rates. Moving on to the rear, the springs once again line up from shortest to tallest in the order of H&R, Eibach, and stock.
This time the H&R and Eibachs both have 6 coils, while I'd consider the stock to have 6.5. Once again measuring spring material thickness, the H&Rs are 15mm
Eibachs are the thickest by a significant margin this time, at 18mm
And stock sit right at 15mm as well
So taking these findings into consideration, it seems like the H&Rs stiffen up the front springs considerably, but only minimally increase rates in the rear. Whereas the Eibachs seem to have minimal rate increase in the front, and a potentially large increase in the rear. While the Eibach rates are probably better overall than the H&R, I'm wondering if a mix of Eibach front and H&R rear might be the best of both worlds? At least in terms of lowering the car with a ride only slightly stiffer than stock.
Well, I'll be installing the Eibachs this weekend, so we will soon know. And do believe that I'll be experimenting the H&Rs in the rear as well, if the Eibachs don't feel right.