increase your profits while reducing your comeback
rate and product liability.
When a customer engages you to repair a
transmission, transfer case or differential, you are immediately
concerned with the present operation or failure of that component. In
short order you and your customer create an agreement in principle
between you regarding the cost of that repair and your responsibility
during and after the process.
In our present society, which has been thoroughly
schooled in the attorney approach to problem resolution, having a
detailed warranty that meets all state and federal laws and protects
both the customer and your shop is a must. In the warranty you should
have a clause that covers related parts. The passage that follows has
been tested in the courts successfully and is placed here as an
example; any language incorporated into your warranty should be crafted
by legal professionals or come from a state or national trade
organization:
“This warranty is limited to replacing the
transmission or parts thereof which upon our examination prove to be
defective. It does not include breakage of gears, damage resulting from
abuse, faulty operation of any part or parts not furnished as part of
the transmission (such as linkage, clutch assemblies, shifters, motor
or transmission mounts, worn or defective driveshaft components, pilot
bearings or bushings, tires and wheels, or electric components etc.),
accident or racing. Units will not be covered under warranty if they
are run out of lubricant, underfilled or overfilled with lubricant, or
filled with the incorrect lubricant.”
This is an example of the need to make sure that
the customer is liable for the correct maintenance of all the items
that are not under your control.
Related parts can become a problem or create a
warranty issue, or they can become a profit-building center. The
difference is in how you and your people are programmed when you
inspect a vehicle for the first time. After a thorough road test, if
possible, the next step is a thorough physical and diagnostic
inspection of the vehicle.
The easiest way to establish a thorough routine is
by creating a physical checklist that all people involved in the
process must complete and sign. List every conceivable piece of
information that you need to know about this vehicle. Battery voltage,
engine vacuum, tire size (measured), tire pressures, fluid condition
and every physical aspect of the driveline, brakes, steering, shocks,
springs, struts etc. must be listed and accounted for.
Now that you have a paper trail and you know what
needs to be replaced, you are in a position to sell some work to your
customer. This is all value added for you and the customer. You now
should have a real handle on what you are getting into and an
opportunity to sell any additional work needed and protect your
warranty. The customer benefits from becoming aware of
the problems in the vehicle that exceed his
original issue. Even if the customer cannot afford to make extra
repairs at this point, you can schedule secondary repairs for later and
qualify their effect on the warranty issues.
Between handling our tech line and the 2% of our
production that is comeback related, it is easy to see where a careless
approach to vehicle inspection becomes quite costly. Driveshafts are a
huge cause of unit failures and apparently are overlooked by shops
rushing to sell and complete work.
At least once a month we see a ZF five-speed
transmission from a Ford truck that has the rear case half demolished.
This is always caused by a failed transmission mount or a bad
driveshaft. The same with an NV241 transfer case in the Dodge truck
line: If the extension housing or rear case half is destroyed on the
transfer case, it will be caused by the driveshaft. Perhaps the problem
occurred after repairs were made and well into the warranty period, but
if you have one of these vehicles with this type of problem on the
initial inspection, sell the customer a driveshaft.
Perhaps we take universal joints for granted
because they seem to be simple old technology, but remember that the
driveshaft is spinning about three to four times as fast as the tires.
The U joint on the input side is spinning at the same speed, but the
output side will speed up and slow down twice per revolution because of
driveline angle. The output yoke is traveling
basically in an elliptical path while the input is in a circular
motion. Driveline angles must be as equal as possible to cancel out the
speed differences, and these angles change with suspension movement,
load on the vehicle, spring and shock wear, and modifications such as
lift kits.
The driveshaft also is exposed to weather and road
hazards, which can change balance immediately. A third problem
frequently created with driveshafts is damage to transmission or
transfer-case seals due to sloppy installation. It is common for a
technician to roll the inner lip on an extension-housing seal when
installing the driveshaft yoke improperly. On the M5R1 series of
Mazda-built transmissions in the Ford light-truck line this causes many
lube-related failures, as the leak is slight and sometimes is not
noticed for months.
There are many instances in which driveshafts
should be sent out for balancing and alignment and need a fresh set of
joints. This makes you more money and prevents a nasty comeback. Look
at the rear springs and make sure that the coils or leaves are in good
shape. If you have a doubt, measure from the frame to the rear housing
on both sides to see whether there is a difference. Remember, your
customer thinks that GVW means he can put in as much concrete block as
it takes to fill the bed.
Check the rear and front differentials for proper
fluid level, leaks, loose pinion lock nuts and proper backlash. The
most-commonly misdiagnosed noise is from a worn rear differential and
“walks” through driveshafts to appear as if coming from the
transmission or transfer case. I would love to have a dollar for every
unit that was disassembled when the cause was in the differential.
Tires and wheels play a huge part in creating
diagnostic problems for the repair shop. Ignore tire size (measured)
and pressures at your peril. Mismatched tires create at least 20% of
all codes and failures in late-model transfer cases. With the advances
in computer integration in the vehicle there are any number of programs
(ABS, stability control, traction control, automatic all-wheel drive
etc.) that depend on accurate wheel-speed readings to function. You
cannot have any accuracy if the tire sizes vary more than one-quarter
inch or less. This tire-size difference kills transfer cases equipped
with clutch packs and viscous couplings, and it damages differentials.
If tire size/pressure is part of your checklist, your life will grow
less complicated.
A quick check for electrical codes also is part of
the road to peace. History codes can tell you of past problems, and
with the complexity of the integrated electronic systems and vehicle
multiplexing, you need to know before you quote. We have seen problems
with Ford Explorer models equipped with the BW 4405 transfer case
caused by a shorted wire in the rear-window defroster. Who would have
thought that they were related, but nothing should surprise you today.
On these vehicles the short harness that runs from the transfer case to
under the driver seat is a common failure. The usual symptom is that
the transfer case will go from 2WD to 4WDLow without being commanded by
the driver. This usually breaks the transfer-case low-range fork, as
this shift is intended to be made only under 3 kilometers per hour with
the brake engaged and the transmission in neutral. The shorted harness
will bypass all safety parameters in the design.
Related parts are a path to increased profit and
better workmanship. Limit your liability to the customer, and make him
responsible for the proper care and maintenance of his vehicle. Careful
initial inspection and a thoroughly written checklist will add to your
profits and create a professional working environment for everyone in
the shop. Related parts have a huge influence on how long your work
will satisfy your customer, and making your customer aware that there
are no unimportant parts on the car goes a long way toward making him
pro-active on maintenance. 
