Now maybe I am not understanding the physics here, but this does not make
sense to me. The function of the cruise control is to MAINTAIN a constant
speed of the vehicle. I see 4 possible situations here:
1. If traction is lost to the rear wheels due to hydroplaning and the
vehicle is under cruise control, the wheels would spin faster, causing the
cruise control to reduce the amount of throttle to slow the wheel speed down
to maintain the “set” speed. Not accelerate the vehicle. Reaction time of
the cruise system to close the throttle is important here.
2. If the vehicle is under manual throttle control and the driver does not
react to a loss of traction and holds the throttle steady, then the rear
wheels will spin even faster than the vehicle speed. Reaction time of the
driver to close the throttle is important here.
3. If the vehicle is on cruise control and slowing down below the “set”
speed due to a loss of traction, the cruise would position the throttle to
maintain the rear wheels at the “set” speed. This would also cause the rear
wheel to spin faster (at the set speed) than the vehicle speed (slower than
the set speed). This may be what the patrol officer meant in the story
below.
4. I think the proper reaction of a vehicle under manual control is to
remove all throttle immediately and coast until steering control is felt
again. Do NOT apply the brakes.
All of the above applies to a rear drive vehicle, like our ForwardLooks, as
described in the original story below. Situations 1 to 3 could mean loss of
control and a spin. The bottom line of the patrol officer’s advice is good,
even if the “acceleration” of the vehicle idea is wrong. In slippery
conditions, do not use cruise.
Front wheel drive vehicles may react very differently. When taking your foot
off the throttle to coast, the engine will cause some engine braking on the
drive wheels. If the drive wheels are in front, the front drags while the
rear coasts. While coasting in slippery conditions, the rear wheels want to
move faster (less drag) than the front wheels. When the rear wheels get
ahead of the front wheels, you are in BIG trouble.
Significantly worn or bald tires are a major cause of hydroplaning.
Dave Homstad
56 Dodge D500
Minnesota, Land of 10,000 Frozen Lakes
-----Original Message-----
From: Forward Look Mopar Discussion List
[mailto:L-FORWARDLOOK@xxxxxxxxxxxxx]On Behalf Of Floyd D. Harper
Sent: Monday, February 03, 2003 4:57 PM
To: L-FORWARDLOOK@xxxxxxxxxxxxx
Subject: [FWDLK] Safe Driving
FYI Group:
Got the following from a friend and wanted to pass it on for safety's sake.
I'd never heard this but it makes sense.
Floyd D Harper
1960 Dodge Dart Pioneer 2 Door Hardtop
= = = =
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!
Perform random acts of kindness every day.
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