Cruise Control and Rain

NYSpeed Automotive
1

I just got an e-mail from my cousin :

Learned something new today …

Subject: FYI - Safety Notice

Driving In the Rain

I wonder how many people know about
this?
A 36 year old female had an accident
several weeks
ago and totaled her car. A resident of
Kilgore, Texas, she was traveling
between Gladewater &Kilgore. It was
raining, though
not excessively, when her car suddenly
began to
hydroplane and literally flew through
the air. She
was not seriously injured but very
stunned at the
sudden occurrence! When she explained
to the highway patrolman what
had happened he told her something that
every driver
should know -

NEVER DRIVE IN THE RAIN WITH
YOUR CRUISE CONTROL ON.

She had thought she
was being cautious by setting the cruise
control and
maintaining a safe consistent speed in
the rain.
But the highway patrolman told her that
if the
cruise control is on and your car begins
to hydroplane –
when your tires lose contact with the
pavement, your
car will accelerate to a higher rate of
speed and you
take off like an airplane. She told the
patrolman that
was exactly what had occurred. The
highway patrol estimated her car was actually
traveling through the air at 10 to 15
miles per hour
faster than the speed set on the cruise
control.
The patrolman said this warning should
be listed,
on the driver’s seat sun-visor -

NEVER USE THE
CRUISE CONTROL WHEN THE PAVEMENT
IS WET OR ICY,

along with the airbag warning. We tell
our teenagers to set the cruise control
and drive a safe
speed - but we don’t tell them to use
the cruise control
only when the pavement is dry.
The only person the accident victim
found, who
knew this (besides the patrolman), was a
man who had
had a similar accident, totaled his car
and sustained
severe injuries.

If you send this to 15 people and only
one of them
doesn’t know about this, then it was all
worth it. You
might have saved a life."

So naturally, i snoped it.

But, where I agree that using cruise control in the rain is stupid because you should be paying 100% attention and have 100% control over the car when the weather is hazardous, I find it hard to believe the part of the story where a car will “accelerate” when a tire loses traction. With most cars, if you break tires loose, you notice your speedometer climb with the tire speed.

If cruise control is on, it makes your car maintain a constant speed - it doesn’t accelerate faster than it already is.

Not to mention, if car is hydroplaning, there is no traction, and your car is not accelerating. In fact, it is slowing down, perhaps just not in a direction where you want the vehicle to go.

Am I wrong when I think this?

Discuss.

2

If You’re hydroplaning, You are effectively losing forward momentum relative to the road.
However, You’re drive wheels will still be near the set cruise speed. The drive wheels (if hydroplaning) are effectively on rollers at that point, no? So, the CC would not accelerate greatly me thinks.

IOW: If You are on (thick sheet of) ice, and You gradually spin Your drive wheels (which are also the wheels with the VSS) upto 30mph, You can theoretically set the CC @ 30mph… as the wheels slip on the lack of traction the CC will accel or decel to maintain the 30 mph.

:gotme:

3

When CC is on, you hit the brakes, it turns off

if you are hydroplaining you would not stay on the gas, so you’re gonna be on the brakes anyway (not hard, but just a tap of the pedal and cc is off)

CC would only be bad if you just sat there and did nothing and didnt react to hydroplaining…in which case wtf are you doing driving.

4

I could absolutely name some people that would react thus :lol:

5

Hmmm, It shouldnt accelerate because the wheels are not making contact with the ground, there would be no traction to keep the constant propolsion and thus should slow down. Its like when you wach those guys go across water on dirtbikes or snow mobiles, they are not meant to accelerate on water, hence they slow down.

6

right, but cruise control trys to maintain a speed. If the car slows down, unlike a bike it going to try to speed up which will cause more problems…

7

As soon as I saw “will take off like a plane” I stopped reading. Another stupid email started by some dumbass who wanted to see how many other dumbasses would forward it.

Without wings or a ramp, your car will never fly like an airplane. No amount of wheelspin will generate lift.

I run with my cruise on in the rain all the time. If anything, if I start to hydroplane, and the wheels start to spin, the cruise is going to slow the truck down, since with the wheels spinning the indicated speed is going to be higher than the actual speed. All moot though, because if the rain gets bad enough that I might be hydroplaning for an extended period I’m going to:
A. Slow down
B. Turn off cruise and actually pay attention to my driving. Probably put away my cell, my laptop, and my double cheesburger.

I think the best advice would be if you’re too stupid to know how to properly react in this situation you should just stay the fuck home when it rains. In fact, how about you just sell your car and take the bus all the time.

8

BUT…

What if the car was on a conveyor belt?

9

i use my cruise control all the time in rain or sun.never had a problem.

10

:lol: word

11

It will take off and crest at 36000 feet.

12

lol word. I always slow down in the rain.with the tires I have my car gets kinda squirly around corners when it rains.

13

lol. drive wheels are coupled to vss. hyrdoplaning or normal driving will have no effect on wheelspeed other than instantaneous variations in friction.

14

So that’s what’s going on. I can’t count the number of times I’ve been driving in the rain and seen cars spontaneously achieve lift off. I wonder if I could get a 1/4 mile track to hose down my lane to improve my ET’s…

15

call mythbusters!

seeing as this is quite the scientific dilemna and as it has people safety involved i imagine that you could get them to do it bringing all of that into the equation i bet it could be done.

then your question would be answered quite well

…personal opinion CC/= cause accel. in the rain when hydroplaning

16

Words of wisdom… :biglaugh:

17

I find that I’m getting extra bitter lately. No autocrossing, very little boating, just lots of work.

18

1.) both the cop and lady are slack jawwed yokles.
2.) she was actually slowing down while the tires were spinning at the set speed.
3.) the “taking off like an airplane” was actually what we all call “Torque Steer”

i mean come on… seriously, any guy here that has driven a FWD car in the rain has experianced torque steer. It feels like your car is floating to where ever it wants as the tires spin. That cop was just bullshitting her and she believed him because 1) hes cop (and they know everything right?) 2) shes a dumbass that just almost shit her pants so shes not thinking clearly in the first place.

19

Depends was there a conveyor-belt involved? :wink:

And this story can only be true if you toss the following out the window:
A. Physics
B. Common-sense
C. A jet-engine with long rope
D. Any sense of reality

Technially if I used that logic. Put a car in a large puddle on jack stands. And set the cruise control to 88MPH. The car would instaniously take-off into the air, and go back into time by about 15 seconds at the same time. Causing a paradox because that would require the usage of “Time” twice in the same sentance. That, and the car would land on itself every 15 seconds cauing a huge pile-up until one of the many duplicated cars warped back into itself causing a super-dense car that of mass that would multiply every 15 seconds until it was too heavy that not even gravity could move it.

MYTH BUSTED