Posted on 04/12/2013 4:20:29 AM PDT by SMARTY
This morning, I drove to work in the rain. It was raining all the way and it is a highway drive of about 35 miles.
I didn't use the cruise control, because I was told that was not a good idea on wet pavement.
Is that correct?
Makes sense to me due to the threat of hydroplaning. My van hydroplanes at 40 MPH in heavy rain.
I know for a fact that you do not want to use it if their is a chance of snow or ice. The vehicle wants to go the set speed, if it hits ice, the motor goes up trying to maintain that speed.
Probably the same thing with wet roads. Traction rules.
With the traction and stability control in the newest cars, probably not an issue, but as mentioned you can end up with wheel spin in older cars, and that’s not good...
I don’t use CC on wet or snowy/icy surfaces. JMO.
Excellent question!
There are many “barban” or nizal settings on the cruise control potentiometer, and because the solenoids and senders are internal, the accuracy of these settings is a question both of interior and exterior moisture or wetness.
As an aside, the brothers who invented auto AC and Cruise Control (Hiram, Lowrance and Max Bingham) debated without end on this subject with Lowrance and Hiram insisting despite all evidence that water content or droplets in the air made no difference whatsoever.
Now, thankfully, it is generally believed by experts that a minimum of humidity is critical for the proper functioning of cruise control, and that you should bypass both Lo and Hi and set your A/C all the way to Max.
My opinion:
Wet road: Okay.
Icy road: A bad idea with rear-wheel drive. Okay with front-wheel drive.
I don’t know where people get the idea that the engine will rev unsafely on ice. If the speed is set at, say, 40, the engine is going to turn the wheels at a speed that corresponds to 40, even if the car is going a bit slower than 40.
OK
It made sense not to use it in the rain or when we have snow and ice.
Too bad..I get really great gas mileage setting the thing and just going at a steady speed.
carriage_hill~:” I don’t use CC on wet or snowy/icy surfaces. JMO. “
Agreed !
Ever notice the number of SUVs that hydroplane in Florida into the meridian (?)
where the roads are designed for water run off ?
Cruise control kills on slippery surfaces.
I use cruise control a lot, even on icy roads. I installed my first cruise control on a new 1973 Chevy van, and have used it ever since. I don't recall that it has ever inadvertently spun a tire on wet roads. It has spun a tire on icy roads possibly once or twice, and I lived where there were a LOT of icy roads.
Its not a good idea.
Yes, because if you hydroplane, you have to tap the brakes (or would instinctively) and that would make it way worse.
I have a vehicle with a dynamic cruise control system, where it follows the vehicle in front of you, up to the speed you set it. If you have the wipers on (beyond intermittent), the dynamic part of the cruise control will shut off. But you then revert to a conventional system and can drive all day on it.
This tells me that, at least, the manufacturer was not concerned about using a cruise control in the rain - and I agree. I’ve had cruise controls longer than I’ve had cars (and I’ve had cars for decades - my first cruise control sat in a box waiting for me to get my first car).
I never had ANY of the problems that people claim (sleepiness, control, etc.). I’ve never had a cruise control do a burnout on wet pavement, ever. They simply don’t gun the engine to that level. On ice, as long as you’re up to your speed, it’s no different than using the throttle - and I’ve done that many, many, times.
So just ignore the IDIOT advice. It’s safer to be looking out your windshield when driving than to have to keep looking at your speedometer.
The speed is measured by the rotational speed of the transmission including the gear currently in use, not movement of the car versus the road by some magical sensor or gps.
If your tires slip on any slippery surface, snow, ice, wet, etc, the tires and the drive train initially speed up, even though the vehicle itself hasn’t accelerated in forward motion. So the cruise control would actually try to slow down, not speed up.
If they added some kind of mechanical speed sensor at a tire that was not a drive tire, like used on a bicycle, it would do the opposite, sensing that tire slowing down and try to speed up the slipping drive wheel.
I can think of no functional constraints with today's cars - it's all human-oriented as far as the pros/cons.
Personally, unless I’m on a long interstate thru the western states, I’d rather not use CC. I don’t feel that I have control anymore until I tap the gas/brake pedal to disengage it.
Even driving too fast on wet roads, with today’s wide (traction) tire causes hydoplaning. I slow down, stay in the right lane, and let ‘em pass me by the scores. I don’t need any wrecks; seen too much carnage on the road in my life. Nothing wrong with doing the speed limit or less in a bad storm.
It happened to me once in heavy rain on cruise control scared the crap out of me when my steering went away. Kicked off CC as soon as it happened.
Right, vehicle speed is a major data imput to the ECM and it needs to be correct. Alot of design is put into it to insure it is correct.
A vehicle will not “rev” the drive wheels in Cruise Mode. The computer will not allow this.
The ECM gets its speed data from wheel censors (ABS) in addition to tranny yoke sensors and constantly compares the two. It correlates every wheel. It knows when one is spinning faster than another.
No manufacturer that has liability lawyers and legal departments is going to design a CC system that is unsafe to use in the rain and the sell it to Kathy Soccermom. They just would not do it. The “safety” for little Johhny and Suzy is too big a liability.... and a selling point.
That being said....
No don’t use it. It is not unsafe as far as the vehicle is concerned. The vehicle will be fine. The vehicle knows what to do.
But if its bad rain, seems to me you would want to have total control. CC is a luxury that kinda lets you relax. You would not want to relax during a storm. Wait till it clears, then relax a bit.
“With the traction and stability control in the newest cars, probably not an issue, but as mentioned you can end up with wheel spin in older cars, and that’s not good...”
Traction control, at least on my Jeep Patriot works to keep wheels turning the same speed by application of a little brake to the spinning wheel. I don’t believe it would have any effect of improving traction of both wheels spinning at same speed.
I would always recommend not using cruise control on slick roads. That way you can help maintain control with the throttle when needed immediatly rather than having to disengage the cruise control first. The immediate reaction to disengage the cruise control is to hit the brake which can be a very bad thing in a slick road. Maybe not as bad as when we didn’t have ABS, but I prefer to start my slowdown with releasing the throttle instead of apping brake.
But maybe I am a control freak.
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