do NOT use your curise control in the rain!!!!!!!!

do NOT use your curise control in the rain!!!!!!!!


First, factory installed cruise controls ALL sense the speed from the
transmission, not the wheels. There are ways of puting cruise control
on cars that don't have cruise control that use magnets on the drive
shaft with a sensor reading how many times it goes by in a certain
amount of time. Therefore, it senses the speed of the engine (thru
the transmission) rather than anything to do with the actual speed of
the tires/wheels or the vehicle. And, if installed correctly - even
on a front wheel drive (FWD) car, the speed is ALWAYS sensed off a
powered axle.

Second, the wheel(s) that is(are) hydroplaning is sliding along on
top of the water and has completely lost traction. It doesn't matter
if the wheel(s) is/are at a dead stop (that is, not turning at all)
or spinning at 100 miles per hour - it has NO traction at all; it is
the same thing as that wheel/tire being on ice. Even pumping the
brakes (as those of us that learned to drive up north on snow
learned) or having antilock brakes [which is essentially the same
thing as having automatic brake pumping] has no effect until the
tires/wheels stop hydroplaning. In other words, if you are
hydroplaning with all 4 tires/wheels or driving on ice, you have lost
complete control of the vehicle.

Third, every car/vehicle has what is called a differential. Even
front wheel drive cars have them. As you go around a corner (or
curve), the outside wheel has to turn faster than the inside wheel
because it has to cover a longer distance than the inside wheel. If
this were not allowed to happen, you would be chewing up your tires
at a very fast rate as one tire (inside) slipped on the pavement
while the other tire (outside) did not.

Fourth, when you are driving in the rain it is fairly unlikely that
you will hydroplane on all 4 tires. Usually the puddles on the road
aren't big enough for all 4 tires to be on them at the same time. So
only one or MAYBE two tires MIGHT hydroplane at the same time when it
is raining - and usually both on the same side of the car. (As an
aside, it is even worse than using your cruise control druing the
rain if you two front (steering) tires hydroplane at the same time -
you loose all steering control until they stop and you are more
likely to end up in the ditch than if something happens because of
the cruise control.)

Okay. Where is all of this leading? It leads to the reason it is VERY
BAD to be using your speed/cruise control while it is raining. It has
nothing to do with the speed of the engine and whether it speeds up
or slows down if a tire starts to hydroplane.

Lets say you are driving down the road in rain with your speed
control on and that you are not on any puddles so no tires are
hydroplaing. The differential is splitting the power between your
driving tires equally because they are turning at the same rate.
Suddenly you hit a long puddle of water with your right tire and it
starts to hydroplane, but the left tire still has traction.
The right tire suddenly speeds up because there is no friction
between it and the pavement; and because the differential is designed
to split the power between the tires - NOT the speed, the left tire
slows down. The cruise control doesn't measure the speed of each
tire - it measures the speed of the transmission. To the cruise
control, the same amount of power is being transfer to the tires;
however, because one tire is slipping and stealing the power from the
other, the (in this case) the right tire is taking all the power to
turn faster than the left.

What does one tire turning faster than the other sound like? Sounds
exactly like what happens in a corner or a curve. When the tire that
is hydroplaning comes out of the puddle and gets traction again, the
power/speeds of the tires are different - just like the car was in a
curve/turn. When the right tire gets traction again, it pushes on the
right side of the car harder (because it is spinning faster and has
more of the power) forcing the car to do what is called a "power
turn" to the left. Since you do not know, and cannot anticipate, when
the tire will regain traction, you cannot compensate for the push to
the left (if the right driving tire is the one hydroplaning.)

In one sentencd: Because the cruise control is electrical/mechanical,
it cannot sense (because it doesn't get the need inputs) what is
happening to the car in the rain and so it cannot do what a normal
driver would do if they were using the gas pedal while driving in the
rain - take their foot off the gas (which takes the power away from
the tires.)

It IS very BAD to use your cruise contol in the rain because the
cruise control is designed for only one thing - to keep your car
moving at a set speed as long as both tires have the same amount of
traction. It isn't designed or built to sense anything else - such as
the differences in speed of the tires.

Oh, to confuse you more, front wheel drive vehicles and vehicles
(like my truck) which have "limited slip" differentials are likely to
do just the opposite of the example. Limited slip differentials sense
if one tire/wheel is slipping and transfer the power to the
NONslipping side. Those vehicles will come out of a hydroplaning
situation looking like they are making a RIGHT turn and therefore
swerve to the right instead of the left. But same result -- BOOM!!!

Final words --- turn off your cruise control when your windshield
starts to get wet. When it drizzles or rains very lightly is even
worse than a nice steady rain. A light rain will lift the oil that
ALL vehicles put on the road just by driving over them. Oil floats on
water and so you will be driving on oil instead of the pavement.
(This is why all high speed curves are made now with grooves in them -
you have to get so much water in the grooves that the oil is carried
away before you can start to slip on the oil.)


oh, and one more thing
the engine would probably speed up because if you hit a puddle big
enough to hydroplane, you would probably slow down enough that the
cruise control would try to speed up the car - making the problem
even worse.

"Dave Gerecke" wrote in message
. ..
do NOT use your curise control in the rain!!!!!!!!

Final words --- turn off your cruise control when your windshield
starts to get wet. When it drizzles or rains very lightly is even
worse than a nice steady rain. A light rain will lift the oil that
ALL vehicles put on the road just by driving over them. Oil floats on
water and so you will be driving on oil instead of the pavement.
(This is why all high speed curves are made now with grooves in them -
you have to get so much water in the grooves that the oil is carried
away before you can start to slip on the oil.)


oh, and one more thing
the engine would probably speed up because if you hit a puddle big
enough to hydroplane, you would probably slow down enough that the
cruise control would try to speed up the car - making the problem
even worse.

Good advice! My father told us years ago to *never* use cruise control when
driving in rain or in snowy or iced-up conditions. Incidentally, that is
advice that I followed today. I drove my sister to Houston to catch her
plane to Ohio, and the driving conditions were some of the worst I have
seen -- torrential downpour and fog as thick as pea soup. Not to mention
lots of lightening! Her plane was delayed 8 hours because planes could not
take off or land. My drive home was even worse than the drive down. I
would have pulled into a motel for the night except that I have to give
final exams beginnin at 8:00 a.m. I came across 5 separate accidents (some
looked major) in the space of a mile or so. I would guess that speed was a
factor under the terrible weather conditions because some vehicles
(especially semis) passed me as if I were standing still -- and that was
with visibility so bad that I could hardly see car lights. I pulled into
filling stations a couple of times when the rain and fog were so bad that I
literally couldn't see anything at at. In one instance, a stream of cars
followed me off the road into the station, and soon the entire area was
filled with cars sitting there waiting for a little break from the rain.
That leads me to suggest another safety tip -- that is, use an exit or pull
into a parking lot of some sort; *do not* pull off onto the shoulder of the
road in conditions like I just described because someone might think you are
still on the road and plough right into the back of your car when you come
to a stop.

MaryL

I'm so relieved to hear you both arrived safely to your destinations.
Best wishes,
Polonca and Soncek

MaryL wrote:
Good advice! My father told us years ago to *never* use cruise control when
driving in rain or in snowy or iced-up conditions. Incidentally, that is
advice that I followed today. I drove my sister to Houston to catch her
plane to Ohio, and the driving conditions were some of the worst I have
seen -- torrential downpour and fog as thick as pea soup. Not to mention
lots of lightening! Her plane was delayed 8 hours because planes could not
take off or land. My drive home was even worse than the drive down.
snip