Ok, I put my springs on my FJ40 this weekend and their roughly 52" in length, I flipped my rear hanger around and used a 1.5" over stock shackle@ 50 degree's and now my spring(while cycling the suspension) over extends to the rear and locks up against the frame to the rear. What's up I thought you wanted the spring at 45 degree's with weight on it for the best flex. I believe I can fix it with a cable to prevent over extending but why? The rear hangers have open retainers and the spring kicks up about 1/2 inch or so and am debating putting on a cable to prevent this but would like to fix it.......if possible. If I move the hanger back then I loose the angle and want improved ride and flex....thanks, sfsl

A simple fix to your problem might be a longer shackle. The reason that this happens is that the combined length of your spring hanger to shackle hanger and the length of the shackle is roughly the same as the flattened length of the spring. Lengthening the shackle will allow the spring to flatten out without the shackle having to go all the way to the frame. The other solution is to move the shackle hanger.

I usually run my shackles at about 30 degrees. This seems to provide the ride and flex we're all after, without raising these kinds of issues. I sure hope this makes sense:rasta:

Eric, Its not inverting to the frame forward but rather backwards but will try a longer shackle, as this will modify the geometry(sp) and might correct the problem. Wish I had a digi camera to snap a few shots but the vehicle goes to a lower position.(Over cams itself)

Yep, if you don't set up your suspension right, that can happen. Your shackle hanger is too far forward for your spring and shackle lengths. As a general rule, you don't want a 45* shackle with the weight of the vehicle on it, you want a 45* angle when the main leaf is totally FLAT. With the main leaf totally flat, it can't get any longer so the shackle will be at it's furthest rearward position.