Sam's Off-Road Traction Bar
By Jody Campbell
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.
Installation:
The
installation of the Traction Bar does require a welder and someone who knows
how to use it, so if this is not you, then find a buddy who can help you out
or a local shop for this install. The instructions included with the
traction bar were very well written and describe a basic install in full
detail. The instructions stress that during installation, your traction bar
must be nearly perpendicular to the forward shackle, creating a 90 degree
angle. We just about nailed ours at 89 degrees. This is crucial because
keeping the shackle 90 degrees from the traction bar itself keeps the pinion
from being able to rise under load. The other item the directions specify is
that you should attempt to locate the bar as close to the center of the rear
end as possible. Our suggestion to you, Leave the bracket an inch or two
away from the cast center section of the housing on one side or the other so
you have room to run your weld bead. Don't weld to the cast portion of the
axle, trust us this is not a good idea, it may cause the housing to bend and
crack later on, again trust us, it will crack! This is the voice of
experience! Once you have to brackets welded onto the axle tube and the
shackle positioned correctly you can either bolt on the shackle hanger or
weld it in place. We did both. Now simply install the bushings, tighten the
bolts and go give it a test. If you followed the included instructions, you
will have eliminated the evil spring wrap and still have all of the
flexibility afforded by a spring over conversion.
Sam's Off Road
4345 Southwest Blvd
Tulsa, OK 74107
Phone: 1-800-446-5503
FAX: 1-918-446-5373
Web Site: http://www.samsoffroad.com.