Originally Posted by 78-AR-SPIDER
If the cc measures the speed at the wheels why would it increase to 105MPH when the system is set to 65MPH?
Now if the drag caused by the water slowes the car to 50mph and the you regain traction with the wheels at 65mph you might have a issue
I didn't explain my point v well.
I can see the drag of the water vs the wheel speed being a problem alright.
Keep in mind that the onset of hydroplaning sometimes gives an increase in friction/load/resistance. When the car is in full surf-mode, there is a drop in resistance. Skating along the top of the surface is seriously low friction stuff. At least that's what my rear-end accelerometer has always felt.
Theory: speed sensor is on the front wheel. Rear wheels are driven. You hydroplane, the front wheels decelerate, the rears speed up to compensate....
Or, what about fwd with an open diff? One wheel hydroplanes, and it has the speed sensor attached. The other wheel accelerates....
Or, sensor on driven wheels with an LSD. Sudden deceleration of wheels from hydroplaning. Then the wheels are sliding on the surface of the water - a very low friction condition. The CC just increased throttle due to the resistance increase at the onset of hydroplaning. Won't the subsequent sudden decrease in load/rolling resistance result in the wheels accelerating? I doubt that in all circumstances, the CC can respond quickly enough to that scenario. Going uphill perhaps....
Or, you hydroplane going downhill and you've lost any engine braking. You never regain traction....*
Surely new cars don't use speed sensors any more - other than ABS prox switches? Prop shaft speed/speed in gear makes so much more sense.
Also, the 'legend' aspect of this whole thing is a bit ridiculous. So a hydroplaning account gets misinterpreted and breathlessly misreported. BS like: "her car suddenly began to hydro-plane and literally flew through the air"
- that's serious arts-degree-dropout-makes-6-o'clock-newsreader stuff. Classic of what you hear/read from mainstream (non-technical) media.
* My experience: Driving from GA to FL in 1994. Dodge Ram 'kidnapper van'. Heavy tropical-type-2pm rain storm. Going downhill. I didn't know anything about not using cruise in the wet. Holy cow did the Ram-o-van take off!