Need a little extra room to fit those 35 inch tires? Body lift and spring lift not enough? So, the decision is down to coil conversion or spring over. Worried about bump steer and axle wrap?
For the YJ, there is now an option - a spring over lift from Rubicon Express, High Steer System from Terraflex, and a Skyjacker 5th Link.
Larger tires require varying combinations of body and spring lifts. There does come a point where body panel trimming is required in addition to the body and spring lift. Then, the choice is spring-over or coil conversion. And, with any modification, there are pros, cons, and trade-offs.
The Terraflex High-Steer replaces the stock tie-rod and steering knuckle with components re-aligned to work with larger tires and higher lifts.
The Skyjacker 5th Link System is designed to stabilize the rear axle and prevent axle wrap.
As I have an existing 2 inch body lift, I opted for the stock springs with the spring over conversion for a total lift of about 6 inches. Just moving the spring u-bolt nuts and protective cover adds much needed ground clearance. Again, it is about pros, cons and trade-offs.
For starters, I am working on a 1994 Wrangler. Axles are modified “stock”. Modified in a Dana 30 is upfront with a Posi-Lock replacing the stock vacuum operated central axle disconnect. And, the rear is a Dane 35 with Warn Black Diamond full-floating axle and lock-out hubs. Gearing is 4.56 with rear Detroit and front Posi-track differential lockers. Between the 4.0L and axles sit an NV 4500 and NP242C.
Installation is straight forward with a few critical points to watch. Welding is required and is best left to and expert with proper welding equipment.
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Centering and pinion angle are critical. It is best to assemble new spring perches and snug bolts to hold everything in position. Re-align spring pack centering pin so that the nut is on top. Adjust axle tilt to provide correct pinion angle adjustment eliminating the need for axle shims. After carefully measuring to locate the axle center and correct positioning of the spring perches, tack weld the spring perches in place.
Now, the bolts can be loosened and spring perches welded in place. When re-assembling, coat the u-bolt ends and spring bushings with anti-seize compound.
As the spring-over kit provides greater articulation, the stock brake lines become a weak link as they would be stretched to capacity. Hence, the kit provides stainless-steel replacement brake lines.
With the high-steer option (lower left), wheel off-set is an issue to consider. Stock jeep wheel offset is 4.5 inches. The high-steer option requires an offset of 3.5 or less to provide clearance for the upper steering control arm ball joint end.
The Skyjacker 5th Link (upper right) option is touted as correcting the axle wrap common with spring-over conversions. While the provided kit does include required parts, it assumes a "stock" transmission and transfer case configuration. Swapping transfer cases should pose no problem as the aftermarket products are designed to fit stock mounting points.
Mounting issues with the 5th link are apparent when the transmission is swapped. As I had swapped transmission and transfer case, the configuration was shifted rearward by almost two inches. This meant the designed mount position for the 5th link cross member would interfere with the transfer case.
The 5th link installation instructions call for positioning the mounting bracket 2.5 inches from the center of the rear bolt on the skid plate. This provided minimum clearance with the transfer case and 5th link cross member. Changing transfer case oil would not be a simple task of removing a drain plug as the cross member is close to the transfer case with no clearance to remove the plug without removing the 5th link cross member.
And, with the cross-member installed in a position to clear the transfer case and skid plate, the brackets that mount to the rear drive shaft will not mount as provided. For my installation, the brackets were trimmed almost 2 inches to retain the correct bolt position angle.
The final consideration involves the sway-bar. Many jeep owners remove the sway bar (and front and rear track bars) to provide more off-road articulation. While this may work well off-road at slow speeds, it does inhibit street performance. A sway-bar is required for on-road stability. Track-bars are optional.
The stock sway-bar with extensions can be used. Mounting tabs meed to be welded to the front axle. After market options are being investigated.
As with all after market installations, some custom modifications may be necessary to complete the installation.
In recap, the installation involved the Rubicon Express Spring-Over Kit, Terreflex High-Steer Kit, and the Skyjacker 5th Link. The install is complimented with Bilstein shocks and BF Goodrich 35 inch KM2 Mud Terrains mounted on 15x8 Eagle Polished Aluminum rims.
Additional pictures of the installation can be viewed in the 4x4Wire TrailShots Galleries.
The installation work was done by:
Off Road Warehouse (ORW)
7915 Balboa Ave
San Diego, CA 92111