maxbraketorque
NAXJA Forum User
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I suppose a number of people would say the best recipe is to not buy them or throw them in the garbage, but I decided to give them a try, in part because my XJ came with the RC 4.5" long arm lift, and because the price is hard to beat ($260 shipped). One of the POs had taken two of the five leaves out of the original leaf pack, and it was badly sagging. They also had installed some crappy shackles, so I tossed those in favor of a set of the Rusty's 0.75" lift shackles which are super beefy and fit well.
For reference, the RC 4.5" lift leaf pack is a 5-leaf pack that is 52.5" eye-to-eye along its arc. I believe that this is about an inch longer than stock. The leaves are a mix of 0.33" thick and 0.26" thick leaves. The main leaf is 0.33", leaves two and three are 0.26", and leaves four and five are 0.33". A leaf spring rate calculator puts the estimated spring rate at 215 lbs/in. The claimed spring rate is 185 lbs/in. With the leaf pack installed and the vehicle sitting at ride height, the shackle is essentially vertical.
I started first with all five leaves, and the ride was very firm, too firm for all but perhaps someone carrying a sh*t-ton of gear and several big passengers. The firmness is perhaps not surprising considering that the shackle is near vertical. Another issue is that the rear of the car is about 1" higher than the front with this combo. RC says to use their leaves with the stock shackle. I tried to do this, but the stock shackle will move through its entire possible range of movement for this spring, and I didn't care for that. However, using the stock shackle would have given a much more level ride height.
Next I removed the middle leaf (0.26" thick). Removing this leaf doesn't actually mess up the leaf pack geometry, at least based on standard approaches. Each leaf is roughly the same amount shorter than the one above it. The estimated spring rate for this arrangement is 190 lbs/in. I manually measured the wheel weight by placing 450 lbs over the rear axle, and I got a measured rate of 260 lbs/in. Amazingly high. This rode quite a bit better than using all five leaves, but it was still overly firm for an outing with minimal load. With this combo the rear is about 0.75" higher than the front.
My next iteration was to take the now unused middle leaf, cut it to match the length of the 0.33" thick bottom leaf, and use it in place of the bottom leaf. The estimated spring rate for this combo is 160 lbs/in. This rides really nice, and the rear is now only about 0.5" higher than the front. I have yet to take it offroad, but I suspect that it will be quite nice for a minimal load outing. Nice thing is that I still have the original bottom leaf, and it only takes me about an hour to swap the bottom leaf, so I can swap back to it relatively easily if I think I need it for some reason. Now I guess I get to see how long it takes before these springs start sagging.
For reference, the RC 4.5" lift leaf pack is a 5-leaf pack that is 52.5" eye-to-eye along its arc. I believe that this is about an inch longer than stock. The leaves are a mix of 0.33" thick and 0.26" thick leaves. The main leaf is 0.33", leaves two and three are 0.26", and leaves four and five are 0.33". A leaf spring rate calculator puts the estimated spring rate at 215 lbs/in. The claimed spring rate is 185 lbs/in. With the leaf pack installed and the vehicle sitting at ride height, the shackle is essentially vertical.
I started first with all five leaves, and the ride was very firm, too firm for all but perhaps someone carrying a sh*t-ton of gear and several big passengers. The firmness is perhaps not surprising considering that the shackle is near vertical. Another issue is that the rear of the car is about 1" higher than the front with this combo. RC says to use their leaves with the stock shackle. I tried to do this, but the stock shackle will move through its entire possible range of movement for this spring, and I didn't care for that. However, using the stock shackle would have given a much more level ride height.
Next I removed the middle leaf (0.26" thick). Removing this leaf doesn't actually mess up the leaf pack geometry, at least based on standard approaches. Each leaf is roughly the same amount shorter than the one above it. The estimated spring rate for this arrangement is 190 lbs/in. I manually measured the wheel weight by placing 450 lbs over the rear axle, and I got a measured rate of 260 lbs/in. Amazingly high. This rode quite a bit better than using all five leaves, but it was still overly firm for an outing with minimal load. With this combo the rear is about 0.75" higher than the front.
My next iteration was to take the now unused middle leaf, cut it to match the length of the 0.33" thick bottom leaf, and use it in place of the bottom leaf. The estimated spring rate for this combo is 160 lbs/in. This rides really nice, and the rear is now only about 0.5" higher than the front. I have yet to take it offroad, but I suspect that it will be quite nice for a minimal load outing. Nice thing is that I still have the original bottom leaf, and it only takes me about an hour to swap the bottom leaf, so I can swap back to it relatively easily if I think I need it for some reason. Now I guess I get to see how long it takes before these springs start sagging.
