Cruise control in the rain

I had this happen on black ice in my 1996 Ford Ranger, the speedometer jumped a few times, truck spun as the rear limited slip axle broke both tires loose, and I slid down the shoulder from 65 mph for 300~400 feet. It was quite a ride.

Blair

Yep, I had it happed to me, the slipping that is. Traveling in the hills of Vermont on Route 91 with cruise control on and the rain started to come down. Within a minute or so I was slipping all over the place. It's never to late to learn a something new!

Drive safe

Wayne

How are you gonna ACCELERATE when hydroplaning?

I suspect most owner's manuals warn against use of CC under icy/wet conditions. Anyway, the CC cannot do anything you couldn't do with your right foot. So don't engage it in conditions where gentle throttle use is prudent.

Carl

The 2nd link says that the first hour of rain is the most dangerous. I think the first minutes or seconds, when even a light rain or drizzle starts, I have slipped like on ice when hitting the brakes. It's like the water must bead up, and the tires slide on them. When it is 95 out and just starting to sprinkle, you wouldn't think, applying the brakes to slow down to wait to merge with traffic on a highway, that the car in front would slip sideways a bit, and then you do. Maybe AWD will make a difference. Will have to see.

VF

>

'All Wheel Drive' definitely does make a difference. My Subaru Liberty AWD was excellent, driving along a very narrow, muddy and slippery road, between farmers properties, made me realise that these cars are a breed of their own. With my previous car, a Ford, I would not even consider for a second to access that road. Having said all that, you guys in America (some states, not all) have far more experience on icy and slippery roads than I do. I hope though, that all around the world, when it rains, everyone slows down by at least 10%.

Graham

Magic!

Apparently, the car no longer needs forward propulsion when hydroplaning, and wind and surface drag are instantly eliminated.

Hey, think of the MPG possibilities!

All of mine have. You'd think common sense would have most folks want to retain full control of the vehicle in non-optimal conditions. But then again, I choose to drive a stick shift, so what do I know?

I've seen this before, but still don't understand it. Cruise Control keeps the drive wheels turning at constant speed, and with an AWD Sub that means all the wheels. To my way of thinking that should prevent skidding.

And hydroplaning is when the tires ride on a film of water instead of pavement. You don't "fly through the air" or "Take off like and airplane".

>

AWD does not make much difference in braking as most cars today have four wheel braking.

As far as spinning tires, AWD does distribute the accelerating forces to

2,3, or 4 tires depending on the system, instead of 1, or 2 tires, therefore reducing the possibility of loosing traction which leads to a spin out.

Blair

in TX everything is bigger even BS

The effect is real, but quite small. As stated, the engine will not rev very high, because it'll only turn the wheels fast enough to maintain the driveshaft speed.

What may be more of a problem is if the wheels are slipping, the damping effect of the mass of the car accelerating/decelerating will no longer be seen by the cruise control unit, making it prone to larger degrees of undershoot/overshoot. Get on a slick road, and pump the gas, not a good idea.

If you put the drive wheels in the air, and set the cruise control to

60mph, it would probably bang the gas on and off- the control loop no longer can control the spoeed smoothly because one of the parameters (damping/momentum) has been changed so dramatically.

Dave

That is sort of correct. The problem is that when the car begins to slip, getting off of the power is the best way to regain grip. With cruise engaged, reaction time is a lot longer and it takes time to disengage the cruise. If the road is really slippery, like glare ice, hitting the brakes, even with ABS, is a very bad idea, and the cruise will try to maintain a constant drivetrain speed irrespective of what the wheels are actually doing. Hence, you lose control.

That makes sense. Thanks for a well thought out explanation.

No problem. I have had it happen to me. I was lucky; I didn't hit anything. But its hard on the ole' undies to be facing oncoming traffic on a slippery road...