By Gene Markel
1. The customer will not be
happy if he brought the car in for a knocking noise, was sold a couple
hundred dollars worth of struts and or ball joints, etc., and the noise
is still there. He takes the car elsewhere and the knocking noise is
fixed with a couple of $20 sway bar bushings. Despite how bad the parts
are, that guy is going to think he got beat. It’s important to address
2. A weak shock absorber, for example, that does
little to dampen bumps will increase feedback through the steering
linkage to the driver. The driver may think he has a steering problem
when, in fact, the real problem is poor ride control. When bad shocks
allow tires to leave the road, you obviously can’t control the vehicle
properly. The driver won’t be able to steer, brake or control the
vehicle. Furthermore, bad shocks create uneven tire wear and excessive
wear on other suspension components.
3. Most people (70 percent)
think the primary function of shocks and struts is to provide a
comfortable ride, so replacement is seen as a low priority. Only 21
percent of the people surveyed by a leading shock manufacturer knew
that new shocks and struts can improve handling and ride control.
If the protective rubber boot that seals the shaft is torn, cracked or
leaks, road splash and dirt can enter the strut and accelerate wear. If
the boot has failed, the joint is doomed to a premature death.
If a customer is really serious about improving the handling
characteristics of his vehicle, you can recommend a performance
handling kit that includes stiffer or adjustable shocks/struts, stiffer
(or lowered) springs, a stiffer sway bar and stiffer suspension
6. After seven to 10 years of service, many of these
older systems start to develop leaks that allow air to escape from the
system. The same thing can happen to plastic air lines. Wiring
connectors, solenoids, compressors and height sensors are also
vulnerable to corrosion and vibration, which, over time, may lead to
failures that disrupt the normal operation of the air ride system.
Do a simple bounce test. A bounce test can be used to visually
demonstrate the lack of resistance in badly worn dampers. Push down on
one corner of the vehicle and rock the suspension several times, then
release it. Repeat the test at each corner of the vehicle. Good dampers
should stop the motion within a bounce or two. Weak ones won’t.
8. If brake lines have to be opened to disconnect them
the struts during strut replacement (cutting the brake line mounting
ear can sometimes make this unnecessary), you’ll have to bleed the
9. Don’t reuse the bearing plates unless they
are in perfect condition. Pay close attention to the condition of the
upper bearing plates. These support the weight of the vehicle, and are
often in poor condition. A bad bearing plate can cause steering
stiffness, noise and poor steering return (memory steer).
Inspect the tires. Uneven wear or toe wear would tell you the wheels
are out of alignment. Uneven surface wear across the face of the tire
can indicate weak ride control components. One sign is tire cupping as
a result of improper tire balancing or improper damping force in the
shock absorber. Also, tires may have inside or outside excessive edge
wear from improper wheel alignment. This should also prompt you to
suspect things like worn tie rod ends, collapsed control arm bushings
or maybe a bent strut or spindle.
11. When installing a new
cartridge in a rebuildable strut, about 3-ounce (a shot glass full) of
ATF must be poured into the strut housing to aid heat transfer from the
12. When installing a new cartridge in a rebuildable
strut, follow the installation instructions regarding the use of
spacers or washers under the body nut on rebuildable struts.
Differences in height among replacement cartridges make the use of such
13. Shock absorbers affect weight transfer
from side to side when cornering and from front to back when braking or
accelerating. When shock absorbers are worn, the weight transfer is
excessive. This can overload the front tires while the rear tires lose
grip, and go from sticking to sliding, causing brake lock-up and loss
of control of the vehicle. Tire adhesion is critical to safety and
handling, especially in sudden avoidance maneuvers.