october2023 - 29

Here are the top six areas of focus in suspensions, including how to
identify problem areas and how to fix them, helping to smooth out the
inspection process and ultimately creating a more comfortable ride.
EVIDENCE OF MOVEMENT
» Cracked edges on a bushing is evidence
it's nearing the end of its useful life.
Link Mfg.
EVIDENCE OF MOVEMENT
» Look for signs of scraping around a bolt to determine if it's under-torqued.
Under-torqued bolts
The most typical damage happens because of
loose fasteners that were not torqued properly
at the initial install, said Mark Molitor, sr. product
manager of chassis suspensions at Link
Mfg. " Maybe it's only hit 75% of what it should
have been torqued to, " he noted.
Before you can tell for sure if a fastener is
under-torqued, a shakeout test should be
performed. " You want to drive around for 500
to 1,000 miles to shake things loose, " Molitor
explained. " Then the technician can go around
and start looking for signs of movement. "
The most apparent sign that sliding has
occurred is if the area around the washer or
bracket appears different than the surrounding
area, typically because the loose brackets
scrape off dirt.
A visual inspection is the preferred method
over listening for clanking, Molitor said,
because the suspension systems on a work
truck, like a dump truck or cement mixer,
are too far from the driver to hear. Plus, the
symphony of other rattling equipment doesn't
help. So stick with the eye test.
Worn rubber bushings
Molitor said worn bushings are likely the
hardest to identify, since many bushings
are not in easily seen places. However, if
the bushings can be seen, then a visual
inspection of the edges can help to determine
if they are getting close to the end of
their life. He said to look for tears, bulging
rubber, or a bent spacer. If seen on a lateral
control rod, for example, it may no longer
be fully controlling the lateral position
of the axle.
LIGHT MISTING
MEDIUM MISTING HEAVY MISTING
LEAKING
" You're going to start wearing out other
suspension parts, and you'll start having
excessive tire wear-at $1,000 each, "
Molitor said. " You don't want a $200 control
rod having a set of (four $1,000 tires)
being worn out prematurely because of a
faulty bushing. "
Worn or damaged bushings can cause
axles to track erratically, increasing tire
wear and possibly reducing fuel mileage,
Blaine Brothers' Adams said, adding that
misaligned air springs may likely be an
indication of worn bushings, alignment
issues, or fatigued U-bolts.
» Misting is a sign that the seals are lubricated, but oil runs show evidence of a leak.
Shock absorber leaks
Shock absorbers should be inspected for damage to the shock body or the rubber mounting
component, advised Melanie Elliott, marketing manager at Hendrickson. A leaking shock is not an
out-of-service issue, but Elliot warned it can lead to reduced service life, increased tire wear, and
ride quality issues.
A warm shock still provides some level of damping, so take the truck out on a short trip and then
feel the shock, Link's Molitor explained. Touch the frame rail to get a reference temperature, and if
the shock is not warmer, it no longer provides the necessary damping, adding that a little bit of oil
coming out is acceptable.
" That just means that it's keeping the seals lubricated. So misting is good, but runs are bad, "
Molitor said. " Shine is fine. "
» A bent spacer is likely the result
of a worn rubber bushing.
Link Mfg.
October 2023 | FleetMaintenance.com
29
Link Mfg.
Link Mfg.

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october2023

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