Post by Archangel on Feb 6, 2007 22:22:35 GMT -5
Ok, so I've been working this for a few days now and figured I'd finally post it. I was asked via pm a couple of days ago about an SOA. I've done a few SOA's now, including my own, and I thought I'd offer this up to anyone with a YJ who's interested in doing an SOA.
If you have good welding and fabricating skills, a spring over conversion is a fairly inexpensive way to get big, meaty tires under your YJ (or any leaf sprung jeep). You can even use your existing springs, and the aftermarket pieces that are required for the conversion (such as longer shocks, slip-yoke eliminator, extended brake lines, high-steer, etc.) won't break the bank.
The amount of lift achieved by placing the springs on top of the axle tube instead of underneath it (as it came from the factory) is around 5 1/2" inches. In addition to raising the vehicle's center of gravity, serious changes are introduced into the steering and driveline angles that must be addressed. Bump steer increases for example, which is mostly corrected by modifying or installing a steering knuckle. By doing so, it raises the drag link and helps correct the geometry of your steering. In a proper setup, your draglink should parallel your trackbar. When I did my SOA, I removed both my sway-bar and trackbar and I never looked back.
Another issue is the driveline angles. A spring over conversion significantly increases the driveshaft angles between the transfer case yokes and the pinions - a complication of particular concern with the YJ's NP231 transfer case and short rear driveshaft. The rear driveshaft angle can be corrected with a shortened tailshaft housing and output shaft conversion kit (slip yoke eliminator). Now of course, another option is to change the transfer case all together, with a unit such as the Atlas II, but remember, I used the work inexpensive earlier... Atlas II's don't quite fit in that category.
On the rear axle, axle wrap becomes an issue. This is a condition where the leaf spring packs bend in an "S" shape under acceleration. This is corrected by locating the axle longitudinally ( front to rear) to the chassis (as opposed to side to side, which is the job of the rear track bar) with a custom traction bar assembly. There are many offered, and many home brewed solutions to this problem. Do some research and see which works best for you.
So, while the spring over conversion is fundamentally simple, it is a challenging operation that requires patience, good welding skills, and a few parts. Take your time, do it right, and a spring over conversion is a great way to lift your YJ or other leaf sprung jeep. It will perform quite well if its set up properly.
If you have good welding and fabricating skills, a spring over conversion is a fairly inexpensive way to get big, meaty tires under your YJ (or any leaf sprung jeep). You can even use your existing springs, and the aftermarket pieces that are required for the conversion (such as longer shocks, slip-yoke eliminator, extended brake lines, high-steer, etc.) won't break the bank.
The amount of lift achieved by placing the springs on top of the axle tube instead of underneath it (as it came from the factory) is around 5 1/2" inches. In addition to raising the vehicle's center of gravity, serious changes are introduced into the steering and driveline angles that must be addressed. Bump steer increases for example, which is mostly corrected by modifying or installing a steering knuckle. By doing so, it raises the drag link and helps correct the geometry of your steering. In a proper setup, your draglink should parallel your trackbar. When I did my SOA, I removed both my sway-bar and trackbar and I never looked back.
Another issue is the driveline angles. A spring over conversion significantly increases the driveshaft angles between the transfer case yokes and the pinions - a complication of particular concern with the YJ's NP231 transfer case and short rear driveshaft. The rear driveshaft angle can be corrected with a shortened tailshaft housing and output shaft conversion kit (slip yoke eliminator). Now of course, another option is to change the transfer case all together, with a unit such as the Atlas II, but remember, I used the work inexpensive earlier... Atlas II's don't quite fit in that category.
On the rear axle, axle wrap becomes an issue. This is a condition where the leaf spring packs bend in an "S" shape under acceleration. This is corrected by locating the axle longitudinally ( front to rear) to the chassis (as opposed to side to side, which is the job of the rear track bar) with a custom traction bar assembly. There are many offered, and many home brewed solutions to this problem. Do some research and see which works best for you.
So, while the spring over conversion is fundamentally simple, it is a challenging operation that requires patience, good welding skills, and a few parts. Take your time, do it right, and a spring over conversion is a great way to lift your YJ or other leaf sprung jeep. It will perform quite well if its set up properly.