Caliper Clinic: Defective Parts, If Not Monitored, Can Easily Strip A Company Of Its Profits - Engine Builder Magazine
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Caliper Clinic: Defective Parts, If Not Monitored, Can Easily Strip A Company Of Its Profits


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Defects exist in almost all products. Preferably,
defects are found and corrected prior to shipment to the customer.
However, on occasion a defect can be overlooked and end up in
the customer’s hands. Not all defects result in an unsafe condition.
But even a product that is boxed or labeled incorrectly can leave
the customer with a sour taste in their mouth long after the issue
has been resolved.

Defective parts, if not monitored, can easily
strip a company of its profits. An automotive parts rebuilding
association has been quoted in the past as saying that the automotive
hydraulic parts industry has an average of between 4%-6% warranty
and defects rate. Defects as well as warranty claims not only
affect a company’s profits; they erode customer confidence in
a specific rebuilder’s product as well as potentially that of
all rebuilt products. With the stakes this high, anyone can see
why it is so critical to be able to define the root cause of defects
and warranties and to take corrective action quickly.


Defects and warranties can be separated into
two categories – Actual and Alleged. This is important not only
to harness a customer who may be manipulating you for their own
benefit, but also to show you which customers actually need to
learn proper diagnostics and installation procedures. Additionally,
separating actual from alleged warranties will allow you to focus
your efforts on correcting actual root causes of a return.

Some people are unaware of the difference between
a defect and a warranty. A defect is a fault or imperfection of
a part prior to installation or use. A warranty is a defect that
has affected the integrity or implied performance of a part. In
most cases, a warranty occurs after the part has been installed.


To help define these further, some common examples
of brake caliper defects and warranties are listed below. Note
that the types of defects and warranties listed below may be caused
by an actual defect at the rebuilder’s facilities, however, it
is possible to cause many of these same conditions while installing
the product on the vehicle.

Types of defects

Stripped Threads
– May have been damaged during rebuilding, however, it’s also
possible that the damage was done by the customer during installation.

Missing Parts
– Parts may have been left out during rebuilding or possibly pilfered
by the customer.

Leaks – Seal
damage may have been done during piston installation by the rebuilder,
however, it’s also possible to damage a seal with extreme heat
or contaminated brake fluid.


Boxed incorrectly
– The box may have been labeled incorrectly, but occasionally
the customer orders the wrong part number and simply needs to
return the one that was sent.

Caliper will not fit
– A caliper that will not fit over the rotor could be caused by
brake pads that are too thick, an incorrect bracket, or a piston
that is too long. On occasion the cause is a rotor that is too

Types of warranties

Stuck piston
– The use of a substandard piston will cause sticking, however,
using contaminated fluid may also cause the seal to swell and
the piston to stick. Extreme heat around the seal area can also
affect piston movement.


Premature pad wear
– There are many things that can affect brake pad wear, however,
there are some telltale signs that may help determine the true
cause. Extreme inner pad wear with normal outer pad wear can be
caused by seal swell or piston damage, but it can also be caused
by riding the brake pedal such as in "two-footed driving."

Extreme outer pad wear with normal inner pad
wear can be caused by slides, pins, bolts or bushings that are
binding or stuck due to lack of lubrication or incorrect lubrication.
With this type of situation it is common to find petroleum-based
lubricants were used and caused swelling of the rubber which caused
the caliper to bind.


Extreme pad wear on both inner and outer pads
may be caused by an improper rotor surface, a damaged brake line
or hose, or simply aggressive driving habits.

Loose parts
Loose parts may be due to incorrect parts or parts that were installed
incorrectly during rebuilding. However, don’t rule out a worn
casting or possibly incorrect installation by the customer.

Noise – Noise
is probably the most common brake complaint when only brake pads
have been replaced or when it is required that the technician
assemble the hardware and brake pads into the caliper. An improper
rotor surface, improper lubrication, loose brake pads or foreign
material that has contaminated the friction surface can also cause


The chances of noise can be greatly reduced
when the caliper has all pads and hardware properly attached and
lubricated. Constrained layer shims can further aid in noise control.

Because many customers will not use a warranty
card or take the time to write out the reason for each return,
it may be difficult to determine the reason for the return. Incorporating
check-off boxes with common return reason(s) printed on the package
will allow the customer to fill in the reason easily. It will
also ensure that the product is returned in your box.


All product returns should be isolated from
all other inventory until the return can be inspected and the
true cause identified. Each customer return should be logged on
a spreadsheet that lists the product part number, alleged problem
and your findings.

One common check that often gets overlooked
is to verify that the returned part is actually a part that you
produced. Separating product returns into different categories
and carefully reviewing them on a regular basis will allow you
to determine where there may be production problems, incorrect
or substandard parts or materials, incomplete procedures, lack
of training or possibly a customer that is "playing games"
at your expense. Once this information is determined, what you
do with it is up to you.


As you can see, determining the true cause
of a return may not always be easy. However, it will tell you
a lot about what you may be doing wrong. It may also tell you
a lot about your customer or your customer’s customer as well.

Engine Builder Magazine