Fleet Maintenance - 33

But if you don't take out enough, then when you
push the pin in it can cause an uneven wear again
between the bushing."
Meritor offers two different types of no-ream
bushings as well, including the FastSet spiral
bushing which can be twisted into the knuckle
by hand.
"That's the easiest way for anyone, even a new
technician, to be able to complete a front steer
[axle kingpin] job," Stockwell says.
"When installing the bushings on the spindles, we always recommend doing a spindle
spread [test] - pass the kingpin from one bushing
to the other bushing and it should feel as a slip
feels with no binding," Ayala says. "There are
two bushings per spindle, and you can check if
the pin goes through one bushing or the other,
but the pin should go through both bushings
at the same time. Sometimes technicians forget
to do this. They go and install the kingpin and
finish the repair and the stiff steering continues
to happen because the bushing will not align.
That's a key test before you go in and complete
the install."
Installing the lip seals is another important
step in steer axle kingpin installation. There
is a lip seal for each bushing, facing towards
the axle. The lip seal allows grease to come out
from the bushing, allowing worn grease and any
contaminants to be removed, while simultaneously preventing contamination from going into
the bushings. As vehicles go through various
environments, the axle encounters dust and
moisture. If the lip seal is not properly installed,
that debris enters the bushing and allows for
wear and degradation.
With a round bore and properly installed
bushings and seals, technicians can now follow
the axle manufacturer's guideline for assembly
procedures.

Lube it or lose it

Once the knuckle is fastened to the axle beam
via the kingpin, the final step in the installation
procedure is to apply lubrication.
"Lubrication is key for the life of the kingpin,"
says STEMCO's Ayala.
During installation, grease is introduced at two
points in the steer axle kingpin system.
"The upper and lower knuckle caps are threaded to allow for the grease zerk to be installed,"
says Dana Aftermarket's Donnelly. "The grease
zerk is the entry point for greasing once the kingpin kit assembly has been completed. We recommend SAE lithium-based grade 1 or 2 [grease]."
It is required that lubrication be applied to the
steer axle kingpin system beyond its initial application at the time of assembly.
"That's actually the biggest thing [in order] to
keep kingpins in service longer, is making sure
to do the frequent lubrication," says Meritor's
Stockwell. "We suggest a varied schedule based
on the application of the truck. For example, we
recommend [for] a low mileage, hard service
[truck], like a garbage truck or a frequently
stopping city delivery truck, to be [greased]
approximately every 15,000 miles. But a line
haul or a high mileage application can be

»Pictured is a worn shim, part of the
kingpin kit. Dana Aftermarket suggests
replacing all parts of the kingpin kit,
including shims, when servicing.
Photo courtesy of Dana Aftermarket

the wheel end, measuring end play each
time the steer axle is lifted and tracking
increases. Awareness of increasing end
play can alert a fleet to service the kingpin prior to irreversible consequences,
such as excessive tire wear.
Applying lubrication at the appropriate
intervals will not only prolong the life of
the steer axle kingpin, but will ensure its
operational capabilities, mitigate steering difficulties, and ease future servicing
when it comes time to replace the kingpin. Vigilance and discipline will win
out, and a fleet's adherence to adequate
preventive maintenance will increase
vehicle uptime.

done less frequently, like at
every oil change or closer to
50,000 miles."
Meritor developed a chart to
establish a preventive maintenance schedule, recommending intervals at which to
apply lubrication to the steer
axle kingpin depending on
the vocation and usage of the
vehicle in service.
Fleets should also consult
the Technology & Maintenance
Council's
Recommended
Practice 651 to help understand
proper lubrication intervals
and guidelines.
"Maintaining proper lubrication in the system is going
to help a ton and allow for a
long life of the system," Ayala
says. "With proper lubrication,
it even helps with the kingpin
not being locked when it is time
to replace it, because there was
always that lubrication instead
of the rust. Maintaining proper
lubrication is key."

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Conclusion

Steer axle kingpin servicing
is extensive. There are many
different stages throughout the
process, each with their own
considerations to account for
when establishing an efficient
and effective procedure. To
combat common pain points,
fleets can implement practices in each of these stages
that will pay dividends in the
long run. Create a running log
that measures end play with

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Fleet Maintenance

Table of Contents for the Digital Edition of Fleet Maintenance