I read this story somewhere:

>An individual had a wreck a couple of weeks ago and
>totaled their Lincoln Town Car. She hydroplaned on
>Hwy. 135 between Gladewater & Kilgore, Texas. She was
>not hurt, just emotionally rattled!
>
>She learned a lesson I'd like to pass on to you. You
>may know this already--but the highway patrolman told
>her that you should NEVER drive in the rain with your
>cruise control on. He said if you did and hydroplaned
>(which she did) that when your tires were off the road
>your car would accelerate to a high rate of speed
>(which it did). You don't have much, if any control
>when you hydroplane, but you are totally in the hands
>of God when the car accelerates. She took off like she
>was in an airplane. She is so thankful she made it
>through that ordeal. Please pass the word around about
>not using cruise control when the pavement is wet or
>icy. The highway patrolman said this should be on the
>sun-visor with the warning about airbags.
>
>The only person she found out who knew this (besides
>the patrolman) was a man who had a similar accident
>and totaled his car. This has made her wonder if this
>is not why so many of our young people are dying in
>accidents. Be careful out there!

IS this a bunch of BS? What would actually happen if you the cruise control is engaged and you loose complete traction (say, a long stretch of ice). Is there any validity to this story? I'm doubting it...

 

Absolutely ture. Think about it. The cruise control doesn't know you have lost traction. There is a guy I work with and he drives with the cruise in the winter. Drives me nuts on the rare occasion I ride with him. He will hit a small piece of ice and the RPMS jump then go back to normal. I'll bet it tears the hell out of his tires too.

 

I never heard that before, but it sounds like it could be legit

 

sounds like bs to me. cruise regulates according to the speed of the wheels/engine and if they start spinning faster than normal, it will ease on the gas. At least thats what i feel.

 

Cruise control is DEFINETLY not something you want when road conditions aren't optimal. However, that story is a bunch of crap.

Your speedo, and cruise monitor speed by rotations per given time by the drive wheels. Thus, you'll notice that when you are spinning tires in bad weather, or doing a burnout, your speedo will read higher than you are actually moving. Thus, if you have your speedo on when you suddenly lose traction, the cruise control will actually try to maintain the speed at which it was set. She would NOT have accelerated.

HOWEVER, this does not mean, the cruise control may not have added to the problem. Whenever the transmission is NOT in neutral, and you go from grip to slip and back to grip, this CAN cause a loss of control.

Also, it takes a considerably longer time to go from cruise to braking, especially in automatics. Thus in bad weather, braking distances increase EVEN MORE when you use cruise control.

 

I agree with your logic. But let's say you're on an uphill with Cruise on, and your car downshifts to keep a steady speed. Then you hit a long patch of ice. When the car is acclerating to maintain your speed, it will actually stop acclerating to match the speed of the tire with the actual speed of the car...thus not creating a slipping tire which is essentially safer than driving with it off.

 

What will happen is a momentary slip, and rise in RPM's. If cruise is not disengaged through braking or acceleration, which would be natural should one notice slipping with cruise on, there will be slight slowing of the vehicles speed, with the wheels spinning marginally faster than the vehicle speed, notice a decrease in load, then upshift again. When the vehicle retains grip again, the car will notice the decrease in speed, downshift, and accelerate again.

All this grip, slip and grip again will definetly make lose of vehicle control more likely. But on a fwd car, as long as you have your hands on the wheel, and an lsd of some sort, you won't have to worry. If you don't have one, you may get some torque steer. And even then, as long as the speed difference between the rotation of the wheels, and the speed of the vehicle isn't too great, there should be no problems.

This is very much like punctures at high speeds. Many people instinctively slam on the brakes, causing the car to spin, and sometimes flip. If all you did was hold onto the wheel, a puncture on ANY tire, would not cause a spin (assuming road car, setup for road use). In fact, you can even slow down slowly when a tire punctures at highway speeds. As long as you hold onto the wheel, you'll be ok. It's only when nimrods slam on brakes, or overcorrect steering inputs, that accidents like these occur.

 

Unfortunatley, there are lot of those 'nimrods' who drive (no one on this board of course!). Knowing this, I think that it is safer for those drivers to keep it on cruise control in those conditions. I'm saying this because isn't the momentary grip slip and grip experienced with cruise on less harful than the manual "oh crap, let me slam on the breaks" mentality when you don't have cruise on? It's almost like the cruise control acts as a traction control device to replace an ignorant person's erractic brake/accleration movements during loss of traction.

 

Checked on the urban legends page (www.snopes.com - it's pretty cool), and they noted it as "true insofar as it apparently happened". However, they imply that the acceleration described was probably due to the author's emotional reaction, but didn't come right out and say "the car won't accelerate".

 

I think the story is a half truth and the reason the woman crashed is because she didn't know how to control her vehicle. I use my cruise all of the time except on snow/ice covered highways (in blizzard conditions).
When losing control of your vehicle in bad driving conditions you should never leave your cruise control on. Hell, you should never continue to give it gas either. Anytime my car starts to loose control (which is very rare), I throw it into neutral so the car can regain traction on its own. The only thing I do is give the car a few seconds to correct itself. I've been it a few bad situations and I've come out clean by knowing what to do.