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Cruise control in rain


gypsymu

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Excellent Driving Tip:

 

A 36 year old female had an accident several weeks ago. It was raining, though not excessively when her car suddenly began to hydro-planeand literally flew through the air. She was not seriously injured but very stunned at the sudden occurrence!When she explained to the Police Officer what had happened, he told her something that every driver should know -

NEVER DRIVE IN THE RAIN WITH YOUR CRUISE CONTROL ON..

 

She thought she was being cautious by setting the cruise control and maintaining a safe consistent speed in the rain.... But the Police Officer told her that if the cruise control is on,your car will begin to hydro-plane when the tyres lose contact with the road, and your car will accelerate to a higher rate of speed making you take off like an aeroplane. She told the Officer that was exactly what had occurred. The Officer said this warning should be listed, on the driver's seat sun-visor -

NEVER USE THE CRUISE CONTROL WHEN THE ROAD 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 road is dry. The only person the accident victim found who knew this, (besides the Officer), was a man who'd had a similar accident, totaled his car and sustained severe injuries..

NOTE: Some vehicles (like the Toyota Sienna Limited XLE) will not allow you to set the cruise control when the windshield wipers are on.

Even if you send this to 15 people and only one of them doesn't know about it, it's still worth it. You may have saved a life.

I just got this in an email and wondered if anyone else has heard of it.

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A cruise control senses road speed and varies engine power to maintain that speed. If a wheel aqaplanes it looses virtually all grip and would tend to speed up but the CC would cut power to maintain wheel speed. I suspect the real problem is the driver detects a lightening of the steering and that the car is behaving differently touches the brakes automatically disengaging the CC and panics resulting in a loss of control.

 

It might be that The advent of computer cotroling so many aspect of vehicle performance such as ABS and Stability Control and engine management controlling cruise control that makes use of CC in heavy rain undesirable. However until somebody comes up with a satisfactory explanation I am at a loss as to how CC would cause problems.

 

 

 

Many moons ago as a motor patrol constable I attended a specialist Accident Investigation Course. A man from Dunlop was was of the lecturers and showed a film of an E type Jaguar on a floodable test track. Its front tyre were marked out in quadrants with alternate spaces black and white. The car was driven up to aqaplaning speed and the brakes applied stopping the marked wheel. The brakes were released but there was insufficient grip to restart the wheels rotation. Very scary.

 

I have only aquaplaning happen twice at the same place two days apart where perhaps an inch of water was running across the camber of a road, The second time aware of the floodin I was travelling 10mph slower but in both cases the car moved bodily sideways for about a foot and gave a significant twitch as grip was regained.

 

 

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gocro - 2013-11-06 8:49 PM

 

Has the whiff of urban myth. No specifics or citations, just a woman, a policeman a report and oooh a man quoted,oh and the chain letter aspect of telling your friends.

 

 

If you Google it you will find it's been around for some years.

 

 

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malc d - 2013-11-06 9:39 PM

 

gocro - 2013-11-06 8:49 PM

 

Has the whiff of urban myth. No specifics or citations, just a woman, a policeman a report and oooh a man quoted,oh and the chain letter aspect of telling your friends.

 

 

If you Google it you will find it's been around for some years.

 

 

An example here:

 

http://www.snopes.com/autos/techno/wetroad.asp

 

When the German motorhome magazine tested 6 different 215/70 R15 C/CP tyres on Ducato vehicles earlier this year, one test involved resistance to 'straight ahead' aquaplaning and another to resistance to aquaplaning while the vehicle was cornering. There were significant differences, with the Hankook Vantra LT tyre resisting 'straight ahead' aquaplaning until 96.2km/h, whereas Michelin's Agilis Campingtyre aquaplaned at 81.9km/h. The tests were with new unworn tyres of course; as the depth of tread decreases with wear, so a tyre's proneness to aquaplaing will increase.

 

Signs warning of a risk of aquaplaning (aquaplanage) are fairly common on French autoroutes.

 

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I do tend to use cruise in the van when on motorways or dual carriageways if not too busy. When the traffic builds up or i get close to my exit, i turn it off as i like to have full control.

I dont have CC on my Audi (older) but dont miss it, possibly as i am usually driving at higher speeds and tend to be in amongst traffic more.

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I had aquaplaning once and it's quite exciting. I think the best advice is not to touch the brakes because if you do you lock the wheels and then when you find some grip all sorts of things can happen. Likewise don't twiddle the steering wheel. I too cannot understand how cruise control can be a problem.
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The Sienna was a new one on me too but a quick google showed that is equipped with radar cruise control. This system senses traffic ahead and keeps an appropriate distance behind. The trouble is the system cannot sense aquaplaning when grip is near non existant so its best to turn it off in heavy rain.

 

Simples.

 

Now all they need to do is link it with windscreen wiper speed and let the computer take over yet another job that might kep you awake. Is that worth a patent application.

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  • 2 weeks later...

I have had aquaplaning in very heavy rain many years ago in a car on the motorway in France with a strong crosswind.

The effect was bizarre the engine revs increased as the car was buffeted as one of the front wheels lost traction for a second or so.

Directional stability was not lost and it took a while before we realised what had happened, we slowed but it did not happen again.

The tyres were not worn, it was just a very high cross wind and very heavy rain on the exposed motorway from Lille to Dunkirk.

Cruise control in this situation would have reduced engine speed to compensate, this would have been a safe reaction not a dangerous one.

Moving the steering wheel as the steering became lighter probably caused the accident discussed above, a similar effect as when one encounters ice/snow on the road.

 

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  • 2 weeks later...

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