Like you say above, I've read 600lb spring rate.
Did the install last week, took me a few days because I pulled the lower control arms and installed new bushings, lower ball joints, and inner and outer tie rod ends. I also installed Light Racing upper control arms. For the rear I used toytec's 2" superflex coil and the 5160's.
I've only been driving it for two days but so far I am very happy. My 4Runner is my DD but I've always felt the ride was soft and bottomed out too easily. It rode too much like a marshmallow. This new setup rides exactly how I want. Firm over gentle rollers and corners but very smooth over big hits. It's what I think Toyota should have made the stock suspension ride like. I've only driven on road so far but Rebound and compression in the front feel perfect, the front end literally just floats over pot-holed streets, very controlled. I don't have a steel bumper or any extra weight in the rear usually. I can't wait to take it in the dirt, I did some serious rock crawling when I first got my ride 5 years ago and the stock suspension worked great for not having much clearance. I'm sure this will work great in the rocks as well but where it will really shine is on rutted and washboard fire roads. It really works well on high frequency impacts.
The rear compliments the front well, I think the 10% increase in stiffness in the spring rate of the superflex coils works really well with the 5160's. My only criticism is that the rebound might be a touch over damped in the rear. When hitting big transitions or whoops in the freeway you can feel the rear take a second to come back to ride height. It absorbs the impact well but is a split second slow to rebound.
I didn't take any before and after measurements, I'm just hitting 100k miles and the stock springs were sagging a lot, especially the front. When I first assembled the front struts I set the circlip on the 4th, or second to highest groove. What bilstein claims is 2" over stock (when new). From reading the 5th gen forums and how they got more lift than expected I figured I'd end up with about 2.5". Like I said I didn't measure but I was pretty shocked at how high the front came out. I bet it was 3" plus. It came out easily higher than the rear.
Now I know a lot of people are into leveling spacers and such, but I for one like forward rake in my truck. Dead level looks ok, but the second you put something in the back your riding a wheelie down the street, like all those F-250s with six inch lift towing a trailer full of quads riding the rear axle on bump stops.
I ended up moving the circlip down two grooves to the 2nd groove from bottom (which bilstein says is .5" lift). I guessing I ended up with a solid 2" lift. It compliments the rear 2" coils very well. The forward rake appears to match the factory look but everything is about 2" higher. I like the look, the wheel well gap is lower in the front but the bottom line of the rocker panel appears level. My plan is to let both front and rear springs settle in then decide if this is where I'll leave it. Right now I'm leaning towards it staying how it is, but I think some would want to go one step higher in the front.
I do think the fact that I got much more lift that described by Bilstein in annoying for the reason of making an installation decision, but I am glad that there is a lot of lift available in the setup without having the pre-load the front spring a lot by running it on the highest setting.
Anyway, I'm very happy with my decision, even thought it was a leap of faith since as far as I know no one else has installed them on a 4th gen and reported back yet.
My advice to those that get the 6112's is go set it lower than you think you want. And now that I think about it I wouldn't install them with stock rear springs, even on the lowest setting the front will probably end up right at or a little higher than the rear.
Overall I would definitely recommend this setup for those looking the improve and lift the suspension. If you were running a steel front bumper and winch and steel rear bumper and tire carrier I might consider a full coilover setup with a higher spring rate like the radflo or icon. But even so with the amount of lift I got I could always go a step up to make up for the extra weight in the front or even ask eibach for a little heavier weight coil.
I'll report back with pictures in the next few days
