> > Replace your pots. Any pots, regardless of "quality", are a hit and
> > miss affair, some seem to work forever, others die quickly.
> You understand pots very well :) we have been trying to explain that
> they do fail and there is no predicting when, no matter who makes the
> wheel unit and no matter what it costs, a pot is a pot and will fail.
> >Trev
> Of course the guys who spent the price of a new car for thier wheel will
> jump up and down and swear that this isnt true but anyone with any
> ability to understand what a pot is and how they work knows better
>Trev
A word from ECCI about pots. No, a pot is not a pot. Anyone who really
understands what pots are and how they work knows that all
potentiometers are not created equal. There is no mystery about the
failure rate of some pots vs others in a driving system application.
A pot is a mechanical and electrical device that must abide by the laws
of physics just like everything else. Pots are available at every price
level imaginable from .50c to $450 each... yes, $450. What
differentiates them is the engineering of the internals for a given
application, the quality of their construction, and the resulting
performance. Some are designed for kids toys and some are for use in
F-16's.
Most lower priced pots are engineered for a static situation, such as a
set-once-in-a-while audio volume or tone knob application. The use of
this kind of pot in a dynamic constant-motion application such as
driving controls will result in a high failure rate. The use of cheap
general use pots from consumer electronics retailers will also result in
frequent failure, because the construction quality is just not there to
assure accuracy and long life. Internal construction variables include:
bushing material, shaft material, manufacturing tolerances, wiper
geometry, wiper material, resistor material, wear characteristics of the
resistor surface, etc. ECCI has done LOTS of homework on this topic and
uses specially modified potentiomters that are engineered to survive a
very long time with high precision in a driving control application. The
experiences of most ECCI users describing YEARS of pot life with intense
daily use are not chance or fiction.
Another major factor in pot failure is the mechanical construction
quality of the driving system itself. Side loading on the pot bushing is
a very common cause of failure. The causes are different for steering
and pedal units:
#1 is imprecise lateral alignment of the steering shaft with the pot.
ECCI uses precision machined bearing bores with sealed ball bearings for
the steering shaft. When the bore is aligned at the factory it will
never go out of alignment. The use of a flexible connection can minimize
the effect of small side displacements and is needed, even in ECCI units
for installation tolerance, but it must not be too flexible, or steering
precision will be lost.
#2 is axial displacement of the steering shaft. Movement of the steering
shaft forwards and aft will cause wiper failure in the pot. ECCI locks
the steering shaft so it cannot move axially. The ECCI bearing structure
cannot wear over time to cause axial looseness. If the steeering shaft
of a wheel moves in ond out AT ALL, you are likely to have problems.
#3 is excessive side loading of the pedal pots due to the design of the
pedal unit. ECCI pedal units are designed to eliminate torsional and
side loads on the pot shaft that cause failure here in many other units.
ECCI pedal pots last even longer than the steering pots due to the less
frequent motion.
The vast majority of ECCI owners have never had a need to change pots at
all despite heavy use. Most of the small percentage of units that have
needed a replacement were due to two specific problems, each of which
was corrected quickly: one batch of defective pots from our supplier in
early '97, and a warped connector in mid '97. When the 25 units affected
are removed from the statistics, less than five percent of ECCI units
shipped since the inception of our company in 1994 have needed
replacement pots, a record of which we are proud.
There are those out there that will try to sell you less by working hard
to convince you it is the same thing. If anyone wishes to know the
record of ECCI products, just ask ECCI owners, not those who have
something else to sell.
Andy Cers
ECCI
HTTP://ourworld.compuserve.com/homepages/extreme
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