First post here on pirate. After having been lurking for a couple of years...
I have a '98 Cherokee that currently has 2" of lift via 2" lift coils in the front, and a full length add-a-leaf in the rear. ( I think it's rancho... I bought it with it on it 5 years ago...)
I have 33x12.50x15 BFG AT's on it with a LOT of trimming done to the fenders. (cut too much in the back... stupid pinch weld... I'll weld it back eventually)
I have settled on wanting between 4-5" of lift, and the rest will be trimming and bump-stopping.
After DAYS of searching, I have decided that 2" pucks in the front are just as good for crawling as 4" lift coils, as I'm not going to be jumping the heep anytime soon and the amount of up-travel and the spring rate are just fine at the moment. Granted, I'll have to find a way to keep them from falling out if I flex far enough to unseat my springs, but I'm pretty sure I can find a way to solve that problem. The lower control arms that are on my jeep at the moment are just over 16". This should be fine for a 4" lift as the length of arm recommended for 4" lift is 16 3/8" according to http://www.lunghd.com/Tech_Articles/Suspension_Steering_Axles_and_Brakes/Control_Arm_Chart.htm I'm not too concerned about the roughness of ride that I'll get from 3/8" of difference... Eventually I'll do a long arm to provide more articulation but that takes $$$ and I really don't have much (school is expensive).
My real dilemma is what to do in the rear. I have a set of 2" lift shackles nearly made, but I came across a set of 4" lift springs on craigslist the other day, and that started me thinking...
It seems to me that using lift springs really only adds to the stiffness of the ride, and basically functions like a lift block except with more lateral support to limit axle wrap, and decreasing the torque applied to the main spring by decreasing the length of the lever at the axle end. To the best of my knowledge the cause of axle wrap is the torque applied by the twisting of the axle under load. when you use a lift block you increase the length of the lever which increases the amount of torque applied to the spring. This is the major disadvantage to just putting a 4" chunk of metal under the springs and using larger u-bolts. The other disadvantage to using leftover metal from your last project for a lift is that it doesn't actually give you any more usable suspension. As near as I can tell all that it does is move the chassis of your vehicle higher over the axle. This can give more clearance for bigger tires by allowing the tire to pivot more before entering the wheel-well, allowing your tires to actually go into the wheel-well before hitting the outer body panel or fender flare. However, this doesn't provide any more articulation of the suspension. You don't get any more up or down travel out of your suspension, you just stop spashig body panels and cuting those expensive tires. In essence it's a body lift.
Using lift springs alleviates the axle wrap problem by adding more leafs to the pack, each with a decreasing length. This causes only slightly more torque to be applied to the mainspring than stock and therefore spring-wrap is less likely. Other than that, from what I can tell it's really about the same as using a lift block. You are just moving the vehicle higher over the axles and not providing any more articulation. The Up-travel will be limited by the spring rate (which is usually increased in lift spring packs and/or by using an add-a-leaf), as well as the length of your shackle and it's relative starting angle/position.
Using a shackle lift doesn't increase the torque applied to the main leaf. And if your are using a longer shackle you are increasing the amount that the leaf spring can "change length." This allows your axle to have more up or down travel (depending on the starting angle) but not both. It seems to me that using a lift shackle is the only way to actually increase the amount of travel in your rear axle. The other lifts are all just gimmicks to get us to spend more money.
There are limits though. With axle drop comes problems with pinion angle and binding at various other places, along with the problems associated with the slip yoke at the transfer-case. Using a shackle based lift will also cause more torsional stress to be applied to your springs (twisting) and may wear them out faster.
Ok, so that was an incredibly long explanation of what I think I know in order to just ask this question:
To add 2" more lift to my jeep that is actually usable the shackle lift is the right way to go right? Or did I over-look something with the lift spring pack?
Are there other factors to consider?
I know that I'll have to shim my axle with 3.5-4 degree shims so that the pinion angle is correct.
At 4" of total lift according to the guys at Teraflex I will be at the MAXIMUM before I HAVE to do a SYE, and my shocks should still work. I should be able to get by for awhile.
Is there anything I missed? I know I could just put the shackles on and call it good, but all of the little things add up, and when you are already eating Ramen, and it's your daily driver, you want to be sure.
Any help would be appreciated...
I have a '98 Cherokee that currently has 2" of lift via 2" lift coils in the front, and a full length add-a-leaf in the rear. ( I think it's rancho... I bought it with it on it 5 years ago...)
I have 33x12.50x15 BFG AT's on it with a LOT of trimming done to the fenders. (cut too much in the back... stupid pinch weld... I'll weld it back eventually)
I have settled on wanting between 4-5" of lift, and the rest will be trimming and bump-stopping.
After DAYS of searching, I have decided that 2" pucks in the front are just as good for crawling as 4" lift coils, as I'm not going to be jumping the heep anytime soon and the amount of up-travel and the spring rate are just fine at the moment. Granted, I'll have to find a way to keep them from falling out if I flex far enough to unseat my springs, but I'm pretty sure I can find a way to solve that problem. The lower control arms that are on my jeep at the moment are just over 16". This should be fine for a 4" lift as the length of arm recommended for 4" lift is 16 3/8" according to http://www.lunghd.com/Tech_Articles/Suspension_Steering_Axles_and_Brakes/Control_Arm_Chart.htm I'm not too concerned about the roughness of ride that I'll get from 3/8" of difference... Eventually I'll do a long arm to provide more articulation but that takes $$$ and I really don't have much (school is expensive).
My real dilemma is what to do in the rear. I have a set of 2" lift shackles nearly made, but I came across a set of 4" lift springs on craigslist the other day, and that started me thinking...
It seems to me that using lift springs really only adds to the stiffness of the ride, and basically functions like a lift block except with more lateral support to limit axle wrap, and decreasing the torque applied to the main spring by decreasing the length of the lever at the axle end. To the best of my knowledge the cause of axle wrap is the torque applied by the twisting of the axle under load. when you use a lift block you increase the length of the lever which increases the amount of torque applied to the spring. This is the major disadvantage to just putting a 4" chunk of metal under the springs and using larger u-bolts. The other disadvantage to using leftover metal from your last project for a lift is that it doesn't actually give you any more usable suspension. As near as I can tell all that it does is move the chassis of your vehicle higher over the axle. This can give more clearance for bigger tires by allowing the tire to pivot more before entering the wheel-well, allowing your tires to actually go into the wheel-well before hitting the outer body panel or fender flare. However, this doesn't provide any more articulation of the suspension. You don't get any more up or down travel out of your suspension, you just stop spashig body panels and cuting those expensive tires. In essence it's a body lift.
Using lift springs alleviates the axle wrap problem by adding more leafs to the pack, each with a decreasing length. This causes only slightly more torque to be applied to the mainspring than stock and therefore spring-wrap is less likely. Other than that, from what I can tell it's really about the same as using a lift block. You are just moving the vehicle higher over the axles and not providing any more articulation. The Up-travel will be limited by the spring rate (which is usually increased in lift spring packs and/or by using an add-a-leaf), as well as the length of your shackle and it's relative starting angle/position.
Using a shackle lift doesn't increase the torque applied to the main leaf. And if your are using a longer shackle you are increasing the amount that the leaf spring can "change length." This allows your axle to have more up or down travel (depending on the starting angle) but not both. It seems to me that using a lift shackle is the only way to actually increase the amount of travel in your rear axle. The other lifts are all just gimmicks to get us to spend more money.
There are limits though. With axle drop comes problems with pinion angle and binding at various other places, along with the problems associated with the slip yoke at the transfer-case. Using a shackle based lift will also cause more torsional stress to be applied to your springs (twisting) and may wear them out faster.
Ok, so that was an incredibly long explanation of what I think I know in order to just ask this question:
To add 2" more lift to my jeep that is actually usable the shackle lift is the right way to go right? Or did I over-look something with the lift spring pack?
Are there other factors to consider?
I know that I'll have to shim my axle with 3.5-4 degree shims so that the pinion angle is correct.
At 4" of total lift according to the guys at Teraflex I will be at the MAXIMUM before I HAVE to do a SYE, and my shocks should still work. I should be able to get by for awhile.
Is there anything I missed? I know I could just put the shackles on and call it good, but all of the little things add up, and when you are already eating Ramen, and it's your daily driver, you want to be sure.
Any help would be appreciated...
