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Originally Posted by AtomicLabMonkey
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Originally Posted by sperry
The only way I can think of the cruise speeding up in a puddle is in an AWD car... lets say the front hits a puddle and the tires lose traction and slow down... the speed sensor slows down and the cruise opens the throttle. The traction control sends the power to the rear tires that still have traction and the car accelerates. The only problem is that the speed sensor shouldn't read off just the front tires... it's usually in the transmission and reads it there.
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Actually I don't think even this scenario is very realistic, for a couple reasons. If the front drive wheels hit a puddle and lose traction, shouldn't they start spinning faster than the rears which still have traction? Assuming the front wheels are dominating the center diff. and driving the VSS, it would cause the cruise to reduce throttle to control the rising speed input.
Second, even if you assume the original scenario above is plausible, if you're going 65mph that translates out to 1144 inches/second. Take an average wheelbase of 100 inches, and that means it only takes 0.0874 seconds to travel the distance of the wheelbase at that speed. That's well within the response time of a computer, but I don't think the entire electro-mechanical system that constitues a cruise control is going to have a response time near that, let alone have time to accelerate the car any meaningful amount before the rear tires also hit the puddle, which leaves you with no tires with any traction, and no possible acceleration. |
I said I didn't think it made sense...
I was just trying to come up with a fractionally logical explaination, and the best I could do was to come up with something regarding traction control and partial loss of traction.
The biggest flaw is that the car wouldn't even see the speed sensor change due to a partial loss of traction since the speed sensor is in the tranny (I know, I broke mine once
) and it would read the speed of the transmission not an individual tire. So if even one tire was slower, the speed sensor would still have the speed of the fastest tire or some sort of average based on the way the differentials worked.
All that said, even if the story is bunk, there's still a reason not to use cruise in adverse conditions:
you're not in control of the car!! If something happens, the car could be accelerating instead of coasting, and that's real bad news on slippery conditions.