Axle-wrap, it sucks worse than a visit to a proctologist with big, cold hands and long, crusty finger nails. That’s exactly why, when we decided that our Project CJ was getting super-flexy, flat springs mounted over the axle, versus the stock ‘kinda-flexy-but-not-enough-to-impress-your-friends- and-family–under-the-axle’ position, we knew we would be inheriting an age old problem, one we hadn’t ever experienced with our OEM configuration. Its called spring wrap, that’s right folks and it ain’t pretty. What is this you ask? It’s a condition that occurs while ascending a steep hill or mashing the gas pedal, transferring all of the engine torque to your differential causing it to rotate upward, binding the u-joints and turning your leaf springs into a letter “S” instead of a flat condition or a lazy letter “U”. Larger tires, lockers, low gearing, V8 muscle, and super-flexy springs further aggravate this condition. A certain amount of axle wrap is normal, in fact it’s absolutely necessary. Without it, you’d snap U- Joints and other parts left and right. The problem however, is two-fold; one, when your axle “wraps” too much, deflecting upward way too far and binding suspension components or two, when the axle unwraps or “rebounds” to quickly, giving your suspension and rear-end catastrophic results.
We have seen all types of home made traction bars, locating bars, and ladder bars that were meant to eliminate spring wrap. Some worked and most didn’t. The one thing that was common to nearly all of them was that they either limited suspension flex or hampered precious ground clearance. That is until we saw the trick set up on Sam Patton’s (from Sam’s Off Road) big, bad CJ-7. Sam took the basic concept of a ladder bar and figured out a way to let it flex with the suspension. The key to Sam’s traction bar is the shackle used at the forward, pivoting end. To understand how this shackle works you must understand that the only thing causing a leaf spring to wrap up is the pinion being forced to rise when gas pedal gets mashed. This pinion rise is normally not a problem in Jeeps with the springs mounted under the axles, because arched springs have a higher spring rate in order to create the desired lift, and because the curve of the spring actually creates its own resistance to wrapping. With a flat leaf spring the spring rate is substantially lower and the lack of arch allows the spring to deflect easier. Sam’s off road traction bar allows the axle to move forward and backward with the natural flex of the spring because the shackle pivots, but does not allow the pinion to rise and create any wrap in the spring. After we installed the Off-road traction bar our axle wrap problems were instantly cured. We opted for the cheaper of the two traction bars Sam’s offers, our suggestion to you, get the one with Johnny Joints on both ends. (In its simplest form, a Johnny Joint is a highly modified Heim Joint with rubber/poly bushings) Our less expensive option has a Johnny Joint at the forward (shackle) end and two sets of leaf spring bushings at the other. The leaf spring bushings limit travel a bit and cause some binding. With the Johnny Joints in both ends all of the binding is gone. While ours still allows the Jeep to flex very well and cures the axle-wrap problem, the suspension will move much more freely with Johnny Joints at both ends. If you want to give ol’ spring-wrap the finger and kiss it goodbye forever, give the guys at Sam’s Off-Road a call now.