Newsletter Articles
Newsletter articles written by Richard Stewart for Palmer Spring Company,
specialists in truck suspension and brakes
Don't Let Alignment Problems
Get Your Truck DownMost trucks, especially highway tractors, are out of alignment
to some degree or another. Left unattended, alignment problems
can cost you money and make your truck difficult to steer,
affecting safety. But if you learn to recognize the telltale signs—
and take your vehicle to a competent shop for alignment service
as soon as they appear—you can preserve your bottom line as
well as maintain the safety and comfort levels of your truck.
"Short tire life is the biggest cost factor, but it's not the only
one," says Russell Lamoureaux, general manager of the Palmer
Spring Company in Providence, Rhode Island, an independent
shop specializing in truck alignment service, suspension and
brakes. "You burn more fuel when you drag tires that are out
of alignment," he adds. "Plus, you have higher maintenance
costs on components."
Proper alignment involves a number of factors that affect
how the wheels behave when the truck is in motion. They
include camber, caster and toe — terms which relate to the tilt
of the wheels and steering axis. Each of these alignment factors
must be adjusted to precise tolerances to get the best
performance and efficiency out of your truck.
Hitting potholes, curbs and other chassis-shocking hard
objects can affect alignment, notes Lamoureaux. Toe is the
most important setting for heavy-duty trucks, he says, noting
that positive toe, called toe-in, is normally spec'd on steer axles.
Zero toe is best for drive axles and trailer axles.Watch Tire Tread Wear
Uneven tire tread wear is usually the first sign of an alignment
problem. "The fastest tread wear is from incorrect toe," says
Lamoureaux, who has been servicing medium and heavy-duty
trucks for more than 40 years. "For every 1/8" that toe is off,
the tire will drag about 30 feet in a mile. It scrapes the rubber
right off the tire," he says. "I've seen toe be off by 1-1/2".
That's usually when somebody changes their own tie rod ends."
He recommends a front-end alignment afterwards.
A feathered wear pattern in the tread ribs—one edge
rounded and the other sharp—is an indication of a toe problem.
"When you can feel the sharp edges as you move your hand
from the outside of the tire toward the inside, that indicates
that more toe-in is needed," he says. When the sharp edges
can be felt in the opposite direction, less toe-in is prescribed.
Camber, the tilt of the wheel that determines how the tire
sets on the road surface, also affects tread life. Excessive
camber wears out tires quickly and should be corrected as
soon as it is detected, Lamoureaux explains. "Too much
negative camber (wheel tilted inward at the top) wears out
tires on the inside shoulder," he explains. "To much positive
caster (outward tilt at the top) wears them out on the outside
shoulder."
Alignment specialists can often determine the source of a
problem by reading the tread wear on a tire. For that reason
worn tires should not be replaced until after an alignment
service has been completed.
Caster, the forward-aft tilt of the steer axle relative to the
vertical centerline of the wheel, affects handling. "Incorrect
caster can make the truck pull to the left or the right, and it
can set up a low-speed shimmy at around 15 mph," observes
Lamoureaux. "In severe cases the truck has to be stopped
and restarted to stop the shimmy."
Loose wheel bearings and other worn components are
often the cause of problems, so alignment specialists check
all front-end components for wear. "We look for any
mechanical problems on the truck that could be causing
handling problems," he says. That includes brakes, steering
and suspension components.
Tire and wheel imbalance is another common cause of
uneven tire wear. High-speed wheel balancing equipment
makes the job quick and easy. Improper tire pressure is
another culprit. Check it regularly and keep your tires
properly inflated to improve tire life. Excessive tread wear
on both shoulders is typically a sign of an under-inflated
tire, while wear on the center treads signifies overinflation.
Lamoureaux recommends several alignment checks a
year to keep a truck within spec and operating at peak
efficiency. "It doesn't make sense to put off having a truck
aligned when it needs it," says Lamoureaux. "It ends up
costing more in tires and parts if you let it go too long."
Axle Rebushing Offers
Major Maintenance Savings
Hitting potholes, curbs and other hard objects can take a
toll on a truck's steering axle. Over time, the eye holding
the kingpin on each end of the axle can wear from repeated
hard knocks, creating play in the kingpin. The result is
wheel vibration and difficulty in steering the truck,
symptoms similar to an alignment problem.
But a front-end alignment is not the solution in this case.
The answer is rebushing—boring the eye to a larger size
and press-fitting a sleeve to firmly grip a new kingpin.
That's a specialty of Doug Dwyer, manager of the Ace
Spring Division of the Palmer Spring Company. He's
rebushed over 1,200 front axles, saving the owners of
those trucks the cost of buying replacement—easily
$2,000 or more for a new axle, depending on the truck.
"A machine shop can bore and sleeve an axle, too,"
acknowledges Doug. "But they're going to charge three
times as much as we do, since they're not set up to do
axles."
Palmer Spring charges a flat $90 to bore each eye. The
job can also be performed on the eyes of the steering
knuckle, also known as the spindle, which is just as
vulnerable as the axle to deformation due to excessive heavy
service, notes Doug.
"When a truck comes into the Palmer Spring shop with
a wheel vibration problem, the first thing they do is check
for excessive play by rocking the wheels from top to
bottom," he explains. "Even a little bit of movement can
wear your tires out; and you won't be able to steer very
well, either."
Normally the front axle is removed and taken to the
shop at Ace Spring not far from Palmer Spring in
Providence. Customers can also remove the axle in their
own shop and transport it to Ace Spring. Doug will even
take the jig and boring machine
to a customer's shop to do the job without removing the
axle from the truck.
To rebush an axle, he first cleans around the eye and
checks for cracks. "We can repair axles in even the worst
condition—except if they're cracked," he says. "Once
it's cracked, it's junk. You can weld it, but it will never
be 100% safe. That's why we don't do it." He uses weld
to fill in any gouges and grinds it level with the surface.
The shop stocks sleeves and kingpin kits in all the
common sizes for truck axles and spindles. Spindle eye
kits contain all the hardware needed to complete the
repair, including new grease fittings, bolts and thrust
bearings. The kits cost between $75 and several
hundred dollars.
To bore an eye, Doug determines the size of sleeve
he needs, then adjusts the cutting blade on his portable
boring machine, designed especially for the job. A jig
centers the cutting apparatus over the eye, and pulls
the cutter down through the eye, then back out,
completing the boring operation.
Doug next taps the sleeve into the eye, then bores
the sleeve slightly to accept the new kingpin. He fits
the kingpin, then secures it with lockpins, and the axle
is as good as new—for a lot less money than buying new.
Copyright © 1998-2008 Stewart & Associates Communication Arts. All rights reserved.
