4WHEELOFFROAD.COM 4-WHEEL & OFF-ROADNOVEMBER 2019 45
WHAT BREAKS AXLES
“
There
are a lot of
variables
”
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Aftermarket axleshafts bolt
in; yet can benefit from several
advantages over factory offerings.
The better metallurg y of 4130
chromoly is stronger and with-
stands shock loads and torque
loads better than stock axleshafts
do. These Dana 44 shafts also
have more material around the
yoke for even more strength and
are machined to accept full-circle
snap rings.8
Oops! The ring-and-pinion in
the front of this IFS truck was
huge, but that didn’t make a dif-
ferent when the aluminum case
flexed to the point of failure. Thishappened with stock tires in a
low-traction situation when the
traction control tried to transfer
power from one side to the other.9
Rolled splines actually rise
above the diameter of the axle-
shaft so the root of the spline is the
s ame size as the a x leshaf t , rather
than cut into the shaft. This process
is more expensive and complicated
than just cutting the splines, but
results in a stronger axleshaft.10
Yokes are most often broken
as a result of binding, from
when leaf springs wrap or the
suspension droops farther than
the U-joint allows. The larger 1350
yoke on the right is not only stron-
ger than the 1310 yoke on the left
but also allows for more angularity.11
Typically, knuckle breakage
results from a hydraulic ram
that has too much stroke, caus-ing the ram to still apply pressure
after the knuckle is at full lock.
Aftermarket knuckles are available
for Dana 30, Dana 44, Dana 60, and
Toyota k nuck les that are made
from stronger materials, have more
ribbing, and even provide better
steering options than stock.12
This Toyota ring gear broke
as the result of a shock load
that chucked the teeth off the
gear. The tires were spinning on
loose terrain, and the vehicle slid
back and came to a sudden stop.
In this instance a larger ring-and-
pinion would likely have survived
without breaking.13
Full-floating rear axles use a
spindle on the housing, simi-
lar to the front end. This means
that the hub and spindle hold up
the weight of the vehicle and the
axleshaft just has to transfer pow-
er. Full-floating axles are stronger,but al so heav ier, than semifloat
axles, and they predominantly
came from the factory in eight-lug
configurations.14
Drive flanges are stronger
than hubs, but it is easier
to replace a hub than a broken
axleshaft or ring-and-pinion.
Sometimes hub bolts can loosen
and sheer off, which are more of
a challenge to repair. We prefer
studs to bolts for hubs, and ARP
even makes stronger hardware for
some hub applications.15
While these two ARB Air
Lockers are both designed
for a Ford 9-inch, there is a huge
difference in strength between the
t wo. How big? The RD99CE (Com -
petition) locker on the left is 290
percent stronger than the standard
RD99 thank s to forged internal s,
improved lubrication, and deeper
clutch tooth engagement.7
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