That brings me to a couple weeks ago when I picked up a 1/2 Crown from Ak47bravo on here.
I installed the rear springs and there was a noticeable drop and stiffness difference, but in looking at the fronts I realized the Crown springs are nearly identical to the OEMs... The coils are slightly larger, the OD of the spring is a little bigger and the spring is a little shorter overall, but not by much. I took a bunch of measurements off the springs and calculated up the spring rates for them.
Here are some comparison pics between the Crown and OEM coils:
At the same time, I also looked into cutting the stock springs and what sort of spring rate that would produce. If you didn't already know, cutting the springs actually makes them stiffer. It makes sense because the spring is shorter, so there's less of it to share the load and deflect.
The formula here is: Spring Rate = (G*(d^4)) / (8*N*(D^3))
Where G is the torsional modulus, d is the wire diameter, N is the number of active coils, and D is the mean coil diameter.
As you can see, the Crown springs are only 6% stiffer than the OEM ones. Unsurprisingly, the Belltech springs are less stiff than the OEM ones.
What is slightly surprising is how much stiffer the cut springs are. By taking out a single coil, you get a 24% increase in the spring rate. This corresponds to about a 2" drop from what I've been able to see from people that have done it.
Knowing all that, I decided to cut my OEM coils.
I cut off one coil and put them back in, and the truck handles MUCH better. The coils are WAY stiffer than stock and the truck sits at least 2" lower up front. As with all these trucks, the driver's side is slightly lower. I may shim that spring slightly to get the truck level.
I also cut my rear springs, but I don't have any rate calculations on them yet, partly because they're a progressive spring and it's hard to figure out where the change in rates occurs. Originally I cut two coils off, but it still sat too high so I went ahead and cut a third. There's maybe one full low spring rate coil left, so I realistically can't cut any more of the rear off.
Here are the pics of how the truck sits now with one full coil cut from the front and three full coils cut from the rear:
After cutting the rear springs again, I attempted to align the front of the truck. Sadly, I didn't have enough camber or toe adjustment to get it correctly aligned, which was a fear of mine going into this. I pulled my tie rods off and cut a little bit from the end to allow me to bring the toe in a little bit, and it seems like it's pretty close now, but the wheel still sits juuuuust a little to the right. I may take another little bit off the end of the rod and try to align it again.
Here are some pics of how it sat after the first round of cutting the tie rod ends. The toe is damn near zero with it being just a hair off, and the camber is pretty close to zero too. I also think my rear axle is fairly centered left to right, which is surprising. You can also see in these pics how much higher my passenger side is, which is a little bit of a problem. I need to shim the drivers side back up.
After deciding that the rear still sat just a liiiiitle bit too high and realizing that I couldn't cut any more of the coil, I bought a belltech rear spring kit. I went ahead and just threw it in without taking any comparison pictures or measurements of the coils since I was in a hurry. Don't worry, I'll take all the measurements and pics when I put the crown stuff in.
Here's how it sits with the cut OEM fronts and the Belltech rears. I haven't cut any off the belltech either. I'll get some more/better pics, the sun in that one was unavoidable. Also, my drivers side now sits WAY lower in the back than the passenger side. I'm seriously considering a ballast of some sort. And yea, that's a big ass lifted truck in that pic. I'm pretty sure the bed of his truck was higher than the cab on mine...
Yes, that's a double rainbow.
My biggest issue right now is that the front camber is maxed out and I'm fairly sure I still have negative camber. I may see about devising a better way to solve that little issue. I'll keep you guys posted as time goes on.
I'm planning on swapping in the crown springs this next week and running with those for a little bit while I work with QA1 on possible coilovers. We shall see, but I need to take a bunch of measurements on the truck anyways, so this will be my opportunity. Might end up driving the vette to work for a week or so. Ah well.