Fleet Maintenance - 31

car and light truck, heavy duty truck and bus, and
off-highway equipment markets.
"Sometimes [drivers] hear clunky noises coming
out of the steer axle," says Alejandro Ayala, senior
product manager for Kaiser gaff and suspension
products for STEMCO. STEMCO supplies a line of
high-performance systems and components to the
commercial vehicle industry.
If a driver reports any difficulty with the
steering or strange noise from the steer axle,
technicians should further investigate. First, a
technician should check for uneven tire wear.
"With a kingpin issue, it would be inner [shoulder] tire wear," Ayala says. "The tire, instead of
being straight [and] perpendicular to the ground
starts to open from the bottom out. So inner wear
is most common."
Beyond looking for uneven tire wear, technicians can also determine a steer axle kingpin issue
by performing a check on the entire wheel end.
"If they have the truck up, the best way to check
if [the steer axle kingpin] needs to be replaced is to
lift that front axle off the ground and apply pressure to the top of the wheel and on the bottom of
the wheel and check for end play," Stockwell says.
"End play is basically too much movement in the
tire. Obviously, you have to turn left and right,
but you don't want there to be any movement up
and down. Use a dial indicator and do a proper
measured check; if [end play is] over ten thousandths of an inch, we recommend you replace
that [kingpin]. You might not quite feel ten thousandths of an inch [of movement], that sounds like
a very small number. So that's why we recommend
doing it whenever you get the opportunity to have
the axle off the ground."

"Lubrication is
key for the life of
the kingpin."
Alejandro Ayala, senior product
manager for Kaiser gaff and
suspension products for STEMCO

»Meritor's Xact Search helps users find an
appropriate kingpin kit for their steer axle.
Photo courtesy of Meritor

Performing such a procedure with a dial indicator every time the steer axle is lifted will provide
the fleet with a log of end play; staying on top of
increasing end play increments can prevent tire
wear and decrease tire replacement frequency.
"When [the steer axle kingpin is] new, they're
going to have about three to four thousandths
of an inch of play," Ayala says. "It's not a rule,
but that's in general terms. Once it hits the ten
thousandths [range of] movement, those tires are
going to be wearing out fast. And that's the indication you need to replace a kingpin. If you're
inspecting the [movement] and logging that,
you can see when your kingpin needs repair.
Do you wait until the tires are worn? Or, do you
put the new tires on and wear them prematurely because you already have a kingpin [that is]
worn out?"

And now, the hard part

You would be hard pressed to find a technician
that claims they enjoy replacing steer axle kingpins. The procedure is tenuous and time consuming, not to mention technical and precise with
minimal margins for error. Though procedures for
steer axle kingpin removal and installation vary
from vehicle to vehicle, there are some universal
steps, tips, and tricks to consider.
The first step of steer axle kingpin replacement
requires the entire wheel end to be torn down and
removed from the vehicle, leaving only the spindle
knuckle connected to the axle beam.
Once the knuckle caps and the draw keys are
removed, the kingpin itself must be extracted.
"The toughest part of this job is to see how the
kingpin is going to come out," says STEMCO's
Ayala. "Will it come out? Sometimes it is kind of
frozen into the axle and it's very hard to remove.
Sometimes, once [the technician has] removed all
the components, a single tap [to the kingpin] and
the kingpin falls out. That's where the technician
becomes very happy, and says, 'Yeah!'"
However, if the kingpin is seized in the bore,
extraction can be troublesome. The kingpin can
become seized when humidity and debris enter
the bore; over time, that contamination can lead
to rust that can essentially weld the pin and bore
together. Presses, hammers, and any tool at a
technician's disposal will need to be utilized in
order to remove a seized kingpin. STEMCO offers
the QwikeXtract King Pin Removal System,
which includes a 50-ton hydraulic press to aid
technicians in the removal of seized kingpins.
"One of the biggest challenges that technicians
face is getting the bushing out of the knuckle
without damaging the bushing bore," says Dana
Aftermarket's Donnelly. "We recommend they use
a punch to remove the knuckle and a press tool to
reinstall it. It's not a good idea to use a die grinder
for removing the bushing."
With the kingpin removed, technicians will
need to clean and clear the bore before installing a new kingpin kit. With the previous kit
removed and debris cleared, technicians need
to measure to ensure the bore is round; a round
bore will ensure a proper fit of the new kingpin
kit, as well as prevent premature wear on the
new kingpin.

Knuckle vertical
play inspection
Dana Aftermarket suggests performing the
following knuckle vertical play inspection to
understand kingpin wear. Mount a dial indicator
on the axle beam; reference the dial indicator probe on the knuckle cap; using a lever,
pry the steering knuckle downward; zero the
dial indicator; using a lever, pry the steering
knuckle upward. Note the indicator reading.

E FAMILY
1.
2.

1. Reference on top of knuckle
2. Dial indicator
3. Pry bar
4. Pry knuckle downward

D, EFA, I FAMILY
1.
2.

1. Reference on top of knuckle
2. Dial indicator
3. Pry bar
4. Pry knuckle downward
Images courtesy of Dana Aftermarket

STEMCO offers the Axle Pro Equipment (APE)
to help establish a round bore and a properly snug
fit for the steer axle kingpin.
"With the Axle Pro Equipment, we drill the
bore and we treat it to bring it to the OE specs,"
says STEMCO's Ayala. "That bore, we sleeve it
with a hardened steel sleeve that is going to be
stronger than the casting of the axle, thus making
the bore stronger for life. The APE is an equipment to drill that bore, align it, and then fill it
with a sleeve to bring the dimensions back to
where they need to be."

May 2020 | VehicleServicePros.com

http://www.VehicleServicePros.com

Fleet Maintenance

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